添加侧边栏，实现部分文件夹功能。但是界面存在部分问题

src/Notesmaster/.idea/deploymentTargetSelector.xml

@@ -4,6 +4,14 @@
     <selectionStates>
       <SelectionState runConfigName="app">
         <option name="selectionMode" value="DROPDOWN" />
+        <DropdownSelection timestamp="2026-01-19T06:52:55.276577900Z">
+          <Target type="DEFAULT_BOOT">
+            <handle>
+              <DeviceId pluginId="LocalEmulator" identifier="path=C:\Users\啊？\.android\avd\Pixel_4a_API_31.avd" />
+            </handle>
+          </Target>
+        </DropdownSelection>
+        <DialogSelection />
       </SelectionState>
     </selectionStates>
   </component>

src/Notesmaster/app/build.gradle.kts

@@ -4,9 +4,7 @@ plugins {
 
 android {
     namespace = "net.micode.notes"
-    compileSdk {
-        version = release(36)
-    }
+    compileSdk = 36
     buildFeatures {
         viewBinding = true
     }
@@ -30,6 +28,13 @@ android {
             )
         }
     }
+
+    testOptions {
+        unitTests {
+            isIncludeAndroidResources = false
+            isReturnDefaultValues = true
+        }
+    }
     compileOptions {
         sourceCompatibility = JavaVersion.VERSION_11
         targetCompatibility = JavaVersion.VERSION_11
@@ -53,6 +58,8 @@ dependencies {
     implementation(files("D:\\ke\\software_enginering\\httpcomponents-client-4.5.14-bin\\lib\\httpclient-win-4.5.14.jar"))
     implementation(files("D:\\ke\\software_enginering\\httpcomponents-client-4.5.14-bin\\lib\\httpcore-4.4.16.jar"))
     testImplementation(libs.junit)
+    testImplementation(libs.mockito.core)
+    testImplementation(libs.mockito.junit)
     androidTestImplementation(libs.ext.junit)
     androidTestImplementation(libs.espresso.core)
 }

src/Notesmaster/app/src/main/AndroidManifest.xml

@@ -60,7 +60,7 @@
             android:name=".ui.NoteEditActivity"
             android:configChanges="keyboardHidden|orientation|screenSize"
             android:launchMode="singleTop"
-            android:theme="@style/NoteTheme"
+            android:theme="@style/Theme.Notesmaster.Edit"
             android:exported="true">
 
             <!-- 意图过滤器：允许查看笔记 -->

src/Notesmaster/app/src/main/java/net/micode/notes/MainActivity.java

@@ -8,6 +8,8 @@ import androidx.core.graphics.Insets;
 import androidx.core.view.ViewCompat;
 import androidx.core.view.WindowInsetsCompat;
 
+import net.micode.notes.ui.SidebarFragment;
+
 /**
  * 主活动类
  * <p>
@@ -15,14 +17,14 @@ import androidx.core.view.WindowInsetsCompat;
  * 支持边到边显示模式，自动适配系统栏的边距。
  * </p>
  */
-public class MainActivity extends AppCompatActivity {
+public class MainActivity extends AppCompatActivity implements SidebarFragment.OnSidebarItemSelectedListener {
 
     /**
      * 创建活动
      * <p>
      * 初始化活动界面，启用边到边显示模式，并设置窗口边距监听器。
      * </p>
-     * 
+     *
      * @param savedInstanceState 保存的实例状态，用于恢复活动状态
      */
     @Override
@@ -32,7 +34,7 @@ public class MainActivity extends AppCompatActivity {
         EdgeToEdge.enable(this);
         setContentView(R.layout.activity_main);
         // 设置窗口边距监听器，自动适配系统栏
-        ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main), (v, insets) -> {
+        ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main_content), (v, insets) -> {
             // 获取系统栏边距
             Insets systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars());
             // 设置视图内边距以适配系统栏
@@ -40,4 +42,59 @@ public class MainActivity extends AppCompatActivity {
             return insets;
         });
     }
+
+    // ==================== SidebarFragment.OnSidebarItemSelectedListener 实现 ====================
+
+    @Override
+    public void onFolderSelected(long folderId) {
+        // TODO: 实现跳转到指定文件夹
+        // 关闭侧栏
+        closeSidebar();
+    }
+
+    @Override
+    public void onTrashSelected() {
+        // TODO: 实现跳转到回收站
+        // 关闭侧栏
+        closeSidebar();
+    }
+
+    @Override
+    public void onSyncSelected() {
+        // TODO: 实现同步功能
+    }
+
+    @Override
+    public void onLoginSelected() {
+        // TODO: 实现登录功能
+    }
+
+    @Override
+    public void onExportSelected() {
+        // TODO: 实现导出功能
+    }
+
+    @Override
+    public void onSettingsSelected() {
+        // TODO: 实现设置功能
+    }
+
+    @Override
+    public void onCreateFolder() {
+        // TODO: 实现创建文件夹功能
+    }
+
+    @Override
+    public void onCloseSidebar() {
+        closeSidebar();
+    }
+
+    // ==================== 私有方法 ====================
+
+    /**
+     * 关闭侧栏
+     */
+    private void closeSidebar() {
+        // TODO: 实现侧栏关闭功能
+    }
 }

src/Notesmaster/app/src/main/java/net/micode/notes/data/NotesDatabaseHelper.java

@@ -471,7 +471,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
      * @param context 应用上下文
      * @return NotesDatabaseHelper单例实例
      */
-    static synchronized NotesDatabaseHelper getInstance(Context context) {
+    public static synchronized NotesDatabaseHelper getInstance(Context context) {
         if (mInstance == null) {
             mInstance = new NotesDatabaseHelper(context);
         }

src/Notesmaster/app/src/main/java/net/micode/notes/data/NotesRepository.java

@@ -186,22 +186,29 @@ public class NotesRepository {
 
     /**
      * 查询笔记列表（内部方法）
+     * <p>
+     * 同时返回文件夹和便签，文件夹显示在便签之前
+     * </p>
      *
      * @param folderId 文件夹ID
-     * @return 笔记列表
+     * @return 笔记列表（包含文件夹和便签）
      */
     private List<NoteInfo> queryNotes(long folderId) {
         List<NoteInfo> notes = new ArrayList<>();
+        List<NoteInfo> folders = new ArrayList<>();
+        List<NoteInfo> normalNotes = new ArrayList<>();
+
         String selection;
         String[] selectionArgs;
 
         if (folderId == Notes.ID_ROOT_FOLDER) {
-            // 根文件夹：显示所有非系统笔记和有内容的通话记录文件夹
-            selection = ROOT_FOLDER_SELECTION;
+            // 根文件夹：显示所有文件夹和便签
+            selection = "(" + NoteColumns.TYPE + "<>" + Notes.TYPE_SYSTEM + " AND " + NoteColumns.PARENT_ID + "=?) OR (" +
+                        NoteColumns.ID + "=" + Notes.ID_CALL_RECORD_FOLDER + " AND " + NoteColumns.NOTES_COUNT + ">0)";
             selectionArgs = new String[]{String.valueOf(Notes.ID_ROOT_FOLDER)};
         } else {
-            // 子文件夹：只显示该文件夹下的笔记
-            selection = NORMAL_SELECTION;
+            // 子文件夹：显示该文件夹下的文件夹和便签
+            selection = NoteColumns.PARENT_ID + "=? AND " + NoteColumns.TYPE + "<>" + Notes.TYPE_SYSTEM;
             selectionArgs = new String[]{String.valueOf(folderId)};
         }
 
@@ -216,17 +223,198 @@ public class NotesRepository {
         if (cursor != null) {
             try {
                 while (cursor.moveToNext()) {
-                    notes.add(noteFromCursor(cursor));
+                    NoteInfo note = noteFromCursor(cursor);
+                    if (note.type == Notes.TYPE_FOLDER) {
+                        // 文件夹单独收集
+                        folders.add(note);
+                    } else if (note.type == Notes.TYPE_NOTE) {
+                        // 便签收集
+                        normalNotes.add(note);
+                    } else if (note.type == Notes.TYPE_SYSTEM && note.id == Notes.ID_CALL_RECORD_FOLDER) {
+                        // 通话记录文件夹
+                        folders.add(note);
+                    }
                 }
-                Log.d(TAG, "Query returned " + cursor.getCount() + " notes");
+                Log.d(TAG, "Query returned " + folders.size() + " folders and " + normalNotes.size() + " notes");
             } finally {
                 cursor.close();
             }
         }
 
+        // 文件夹按修改时间倒序排列
+        folders.sort((a, b) -> Long.compare(b.modifiedDate, a.modifiedDate));
+        // 便签按修改时间倒序排列
+        normalNotes.sort((a, b) -> Long.compare(b.modifiedDate, a.modifiedDate));
+
+        // 合并：文件夹在前，便签在后
+        notes.addAll(folders);
+        notes.addAll(normalNotes);
+
         return notes;
     }
 
+    /**
+     * 查询单个文件夹信息
+     *
+     * @param folderId 文件夹ID
+     * @return 文件夹信息，如果不存在返回null
+     */
+    public NoteInfo getFolderInfo(long folderId) {
+        if (folderId == Notes.ID_ROOT_FOLDER) {
+            NoteInfo root = new NoteInfo();
+            root.id = Notes.ID_ROOT_FOLDER;
+            root.title = "我的便签";
+            root.snippet = "我的便签";
+            root.type = Notes.TYPE_FOLDER;
+            return root;
+        }
+
+        String selection = NoteColumns.ID + "=?";
+        String[] selectionArgs = new String[]{String.valueOf(folderId)};
+
+        Cursor cursor = contentResolver.query(
+            Notes.CONTENT_NOTE_URI,
+            null,
+            selection,
+            selectionArgs,
+            null
+        );
+
+        if (cursor != null) {
+            try {
+                if (cursor.moveToFirst()) {
+                    return noteFromCursor(cursor);
+                }
+            } finally {
+                cursor.close();
+            }
+        }
+        return null;
+    }
+
+    /**
+     * 查询文件夹的父文件夹ID（异步版本）
+     *
+     * @param folderId 文件夹ID
+     * @param callback 回调接口，返回父文件夹ID
+     */
+    public void getParentFolderId(long folderId, Callback<Long> callback) {
+        executor.execute(() -> {
+            try {
+                long parentId = getParentFolderId(folderId);
+                callback.onSuccess(parentId);
+            } catch (Exception e) {
+                callback.onError(e);
+            }
+        });
+    }
+
+    /**
+     * 查询文件夹的父文件夹ID
+     *
+     * @param folderId 文件夹ID
+     * @return 父文件夹ID，如果不存在返回根文件夹ID
+     */
+    public long getParentFolderId(long folderId) {
+        if (folderId == Notes.ID_ROOT_FOLDER || folderId == Notes.ID_CALL_RECORD_FOLDER) {
+            return Notes.ID_ROOT_FOLDER;
+        }
+
+        NoteInfo folder = getFolderInfo(folderId);
+        if (folder != null) {
+            return folder.parentId;
+        }
+        return Notes.ID_ROOT_FOLDER;
+    }
+
+    /**
+     * 获取文件夹路径（从根到当前）
+     *
+     * @param folderId 当前文件夹ID
+     * @return 文件夹路径列表（从根到当前）
+     */
+    public List<NoteInfo> getFolderPath(long folderId) {
+        List<NoteInfo> path = new ArrayList<>();
+        long currentId = folderId;
+
+        while (currentId != Notes.ID_ROOT_FOLDER) {
+            NoteInfo folder = getFolderInfo(currentId);
+            if (folder == null) {
+                break;
+            }
+            path.add(0, folder); // 添加到列表头部
+            currentId = folder.parentId;
+        }
+
+        // 添加根文件夹
+        NoteInfo root = new NoteInfo();
+        root.id = Notes.ID_ROOT_FOLDER;
+        root.title = "我的便签";
+        root.snippet = "我的便签";
+        root.type = Notes.TYPE_FOLDER;
+        path.add(0, root);
+
+        return path;
+    }
+
+    /**
+     * 获取文件夹路径（异步版本）
+     *
+     * @param folderId 当前文件夹ID
+     * @param callback 回调接口，返回文件夹路径列表
+     */
+    public void getFolderPath(long folderId, Callback<List<NoteInfo>> callback) {
+        executor.execute(() -> {
+            try {
+                List<NoteInfo> path = getFolderPath(folderId);
+                callback.onSuccess(path);
+            } catch (Exception e) {
+                callback.onError(e);
+            }
+        });
+    }
+
+    /**
+     * 创建新文件夹
+     *
+     * @param parentId 父文件夹ID
+     * @param name 文件夹名称
+     * @param callback 回调接口，返回新文件夹的ID
+     */
+    public void createFolder(long parentId, String name, Callback<Long> callback) {
+        executor.execute(() -> {
+            try {
+                ContentValues values = new ContentValues();
+                long currentTime = System.currentTimeMillis();
+
+                values.put(NoteColumns.PARENT_ID, parentId);
+                values.put(NoteColumns.TYPE, Notes.TYPE_FOLDER);
+                values.put(NoteColumns.SNIPPET, name);
+                values.put(NoteColumns.CREATED_DATE, currentTime);
+                values.put(NoteColumns.MODIFIED_DATE, currentTime);
+                values.put(NoteColumns.LOCAL_MODIFIED, 1);
+                values.put(NoteColumns.NOTES_COUNT, 0);
+
+                Uri uri = contentResolver.insert(Notes.CONTENT_NOTE_URI, values);
+
+                Long folderId = 0L;
+                if (uri != null) {
+                    try {
+                        folderId = ContentUris.parseId(uri);
+                    } catch (Exception e) {
+                        Log.e(TAG, "Failed to parse folder ID from URI", e);
+                    }
+                }
+
+                callback.onSuccess(folderId);
+                Log.d(TAG, "Successfully created folder: " + name + " with ID: " + folderId);
+            } catch (Exception e) {
+                Log.e(TAG, "Failed to create folder: " + name, e);
+                callback.onError(e);
+            }
+        });
+    }
+
     /**
      * 创建新笔记
      * <p>

src/Notesmaster/app/src/main/java/net/micode/notes/ui/NoteEditActivity.java

@@ -71,8 +71,11 @@ import java.util.Map;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
+import androidx.appcompat.app.AppCompatActivity;
+import com.google.android.material.appbar.MaterialToolbar;
 
-public class NoteEditActivity extends Activity implements OnClickListener,
+
+public class NoteEditActivity extends AppCompatActivity implements OnClickListener,
         NoteSettingChangedListener, OnTextViewChangeListener {
     /**
      * 笔记头部视图持有者
@@ -143,6 +146,8 @@ public class NoteEditActivity extends Activity implements OnClickListener,
     private SharedPreferences mSharedPrefs;
     private int mFontSizeId;
 
+    private MaterialToolbar toolbar;
+
     private static final String PREFERENCE_FONT_SIZE = "pref_font_size";
 
     private static final int SHORTCUT_ICON_TITLE_MAX_LEN = 10;
@@ -160,6 +165,15 @@ public class NoteEditActivity extends Activity implements OnClickListener,
         super.onCreate(savedInstanceState);
         this.setContentView(R.layout.note_edit);
 
+        // 初始化Toolbar（使用MaterialToolbar，与列表页面一致）
+        MaterialToolbar toolbar = findViewById(R.id.toolbar);
+        setSupportActionBar(toolbar);
+        if (getSupportActionBar() != null) {
+            getSupportActionBar().setDisplayHomeAsUpEnabled(true);
+            getSupportActionBar().setDisplayShowHomeEnabled(true);
+        }
+        toolbar.setNavigationOnClickListener(v -> finish());
+
         if (savedInstanceState == null && !initActivityState(getIntent())) {
             finish();
             return;
@@ -284,6 +298,49 @@ public class NoteEditActivity extends Activity implements OnClickListener,
         return true;
     }
 
+    /**
+     * 初始化资源
+     * <p>
+     * 初始化笔记编辑界面的所有UI组件引用和点击监听器
+     * </p>
+     */
+    private void initResources() {
+        mHeadViewPanel = findViewById(R.id.note_title);
+        mNoteHeaderHolder = new HeadViewHolder();
+        mNoteHeaderHolder.tvModified = findViewById(R.id.tv_modified_date);
+        mNoteHeaderHolder.ivAlertIcon = findViewById(R.id.iv_alert_icon);
+        mNoteHeaderHolder.tvAlertDate = findViewById(R.id.tv_alert_date);
+        mNoteHeaderHolder.ibSetBgColor = findViewById(R.id.btn_set_bg_color);
+        mNoteHeaderHolder.ibSetBgColor.setOnClickListener(this);
+        mNoteEditor = findViewById(R.id.note_edit_view);
+        mNoteEditorPanel = findViewById(R.id.sv_note_edit);
+        mNoteBgColorSelector = findViewById(R.id.note_bg_color_selector);
+
+        // 设置背景颜色选择器的点击事件
+        for (int id : sBgSelectorBtnsMap.keySet()) {
+            ImageView iv = findViewById(id);
+            iv.setOnClickListener(this);
+        }
+
+        mFontSizeSelector = findViewById(R.id.font_size_selector);
+        for (int id : sFontSizeBtnsMap.keySet()) {
+            View view = findViewById(id);
+            view.setOnClickListener(this);
+        }
+
+        mSharedPrefs = PreferenceManager.getDefaultSharedPreferences(this);
+        mFontSizeId = mSharedPrefs.getInt(PREFERENCE_FONT_SIZE, ResourceParser.BG_DEFAULT_FONT_SIZE);
+        /**
+         * HACKME: Fix bug of store the resource id in shared preference.
+         * The id may larger than the length of resources, in this case,
+         * return the {@link ResourceParser#BG_DEFAULT_FONT_SIZE}
+         */
+        if (mFontSizeId >= TextAppearanceResources.getResourcesSize()) {
+            mFontSizeId = ResourceParser.BG_DEFAULT_FONT_SIZE;
+        }
+        mEditTextList = findViewById(R.id.note_edit_list);
+    }
+
     @Override
     protected void onResume() {
         super.onResume();
@@ -430,47 +487,6 @@ public class NoteEditActivity extends Activity implements OnClickListener,
         return true;
     }
 
-    /**
-     * 初始化资源
-     * <p>
-     * 初始化所有UI组件的引用，设置点击监听器，
-     * 并从SharedPreferences中读取字体大小设置。
-     * </p>
-     */
-    private void initResources() {
-        mHeadViewPanel = findViewById(R.id.note_title);
-        mNoteHeaderHolder = new HeadViewHolder();
-        mNoteHeaderHolder.tvModified = (TextView) findViewById(R.id.tv_modified_date);
-        mNoteHeaderHolder.ivAlertIcon = (ImageView) findViewById(R.id.iv_alert_icon);
-        mNoteHeaderHolder.tvAlertDate = (TextView) findViewById(R.id.tv_alert_date);
-        mNoteHeaderHolder.ibSetBgColor = (ImageView) findViewById(R.id.btn_set_bg_color);
-        mNoteHeaderHolder.ibSetBgColor.setOnClickListener(this);
-        mNoteEditor = (EditText) findViewById(R.id.note_edit_view);
-        mNoteEditorPanel = findViewById(R.id.sv_note_edit);
-        mNoteBgColorSelector = findViewById(R.id.note_bg_color_selector);
-        for (int id : sBgSelectorBtnsMap.keySet()) {
-            ImageView iv = (ImageView) findViewById(id);
-            iv.setOnClickListener(this);
-        }
-
-        mFontSizeSelector = findViewById(R.id.font_size_selector);
-        for (int id : sFontSizeBtnsMap.keySet()) {
-            View view = findViewById(id);
-            view.setOnClickListener(this);
-        };
-        mSharedPrefs = PreferenceManager.getDefaultSharedPreferences(this);
-        mFontSizeId = mSharedPrefs.getInt(PREFERENCE_FONT_SIZE, ResourceParser.BG_DEFAULT_FONT_SIZE);
-        /**
-         * HACKME: Fix bug of store the resource id in shared preference.
-         * The id may larger than the length of resources, in this case,
-         * return the {@link ResourceParser#BG_DEFAULT_FONT_SIZE}
-         */
-        if(mFontSizeId >= TextAppearanceResources.getResourcesSize()) {
-            mFontSizeId = ResourceParser.BG_DEFAULT_FONT_SIZE;
-        }
-        mEditTextList = (LinearLayout) findViewById(R.id.note_edit_list);
-    }
-
     /**
      * 活动暂停时保存笔记
      * <p>
@@ -528,7 +544,7 @@ public class NoteEditActivity extends Activity implements OnClickListener,
         if (id == R.id.btn_set_bg_color) {
             mNoteBgColorSelector.setVisibility(View.VISIBLE);
             findViewById(sBgSelectorSelectionMap.get(mWorkingNote.getBgColorId())).setVisibility(
-                    -                    View.VISIBLE);
+                    View.VISIBLE);
         } else if (sBgSelectorBtnsMap.containsKey(id)) {
             findViewById(sBgSelectorSelectionMap.get(mWorkingNote.getBgColorId())).setVisibility(
                     View.GONE);

src/Notesmaster/app/src/main/java/net/micode/notes/ui/NotesListActivity.java

@@ -22,18 +22,31 @@ import android.content.Context;
 import android.content.DialogInterface;
 import android.content.Intent;
 import android.os.Bundle;
+import android.text.InputFilter;
+import android.text.TextUtils;
 import android.util.Log;
 import androidx.appcompat.view.ActionMode;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.View;
+import android.view.WindowInsets;
+import android.view.WindowInsetsController;
+import android.view.WindowManager;
 import android.widget.AdapterView;
 import android.widget.Button;
+import android.widget.EditText;
+import android.widget.LinearLayout;
 import android.widget.ListView;
 import android.widget.PopupMenu;
+import android.widget.TextView;
 import android.widget.Toast;
 
 import androidx.appcompat.app.AppCompatActivity;
+import androidx.core.graphics.Insets;
+import androidx.core.view.ViewCompat;
+import androidx.core.view.WindowCompat;
+import androidx.core.view.WindowInsetsCompat;
+import androidx.drawerlayout.widget.DrawerLayout;
 import androidx.lifecycle.Observer;
 import androidx.lifecycle.ViewModel;
 import androidx.lifecycle.ViewModelProvider;
@@ -64,7 +77,8 @@ import java.util.List;
 public class NotesListActivity extends AppCompatActivity
     implements NoteInfoAdapter.OnNoteButtonClickListener,
                NoteInfoAdapter.OnNoteItemClickListener,
-               NoteInfoAdapter.OnNoteItemLongClickListener {
+               NoteInfoAdapter.OnNoteItemLongClickListener,
+               SidebarFragment.OnSidebarItemSelectedListener {
     private static final String TAG = "NotesListActivity";
     private static final int REQUEST_CODE_OPEN_NODE = 102;
     private static final int REQUEST_CODE_NEW_NODE = 103;
@@ -73,7 +87,13 @@ public class NotesListActivity extends AppCompatActivity
     private ListView notesListView;
     private androidx.appcompat.widget.Toolbar toolbar;
     private NoteInfoAdapter adapter;
-    private androidx.appcompat.view.ActionMode actionMode;
+    private DrawerLayout drawerLayout;
+    private FloatingActionButton fabNewNote;
+    private LinearLayout breadcrumbContainer;
+    private LinearLayout breadcrumbItems;
+
+    // 多选模式状态
+    private boolean isMultiSelectMode = false;
 
     /**
      * 活动创建时的初始化方法
@@ -86,8 +106,21 @@ public class NotesListActivity extends AppCompatActivity
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
+
+        // 启用边缘到边缘显示
+        WindowCompat.setDecorFitsSystemWindows(getWindow(), false);
+
         setContentView(R.layout.note_list);
 
+        // 处理窗口insets（状态栏和导航栏）
+        View mainView = findViewById(android.R.id.content);
+        ViewCompat.setOnApplyWindowInsetsListener(mainView, (v, windowInsets) -> {
+            Insets insets = windowInsets.getInsets(WindowInsetsCompat.Type.systemBars());
+            // 设置内容区域的padding以避免被状态栏遮挡
+            v.setPadding(insets.left, insets.top, insets.right, insets.bottom);
+            return WindowInsetsCompat.CONSUMED;
+        });
+
         initViewModel();
         initViews();
         observeViewModel();
@@ -129,6 +162,11 @@ public class NotesListActivity extends AppCompatActivity
     private void initViews() {
         notesListView = findViewById(R.id.notes_list);
         toolbar = findViewById(R.id.toolbar);
+        drawerLayout = findViewById(R.id.drawer_layout);
+
+        // 初始化面包屑导航
+        breadcrumbContainer = findViewById(R.id.breadcrumb_container);
+        breadcrumbItems = findViewById(R.id.breadcrumb_items);
 
         // 设置适配器
         adapter = new NoteInfoAdapter(this);
@@ -144,7 +182,7 @@ public class NotesListActivity extends AppCompatActivity
                 Object item = parent.getItemAtPosition(position);
                 if (item instanceof NotesRepository.NoteInfo) {
                     NotesRepository.NoteInfo note = (NotesRepository.NoteInfo) item;
-                    openNoteEditor(note);
+                    handleItemClick(note, position);
                 }
             }
         });
@@ -156,18 +194,58 @@ public class NotesListActivity extends AppCompatActivity
             getSupportActionBar().setTitle(R.string.app_name);
         }
 
+        // 初始化为普通模式
+        updateToolbarForNormalMode();
+
+        // 设置 Toolbar 的汉堡菜单按钮点击监听器（打开侧栏）
+        toolbar.setNavigationOnClickListener(v -> {
+            if (drawerLayout != null) {
+                drawerLayout.openDrawer(findViewById(R.id.sidebar_fragment));
+            }
+        });
+
         // Set FAB click event
-        FloatingActionButton fabNewNote = findViewById(R.id.btn_new_note);
+        fabNewNote = findViewById(R.id.btn_new_note);
         if (fabNewNote != null) {
             fabNewNote.setOnClickListener(v -> {
                 Intent intent = new Intent(NotesListActivity.this, NoteEditActivity.class);
                 intent.setAction(Intent.ACTION_INSERT_OR_EDIT);
-                intent.putExtra(Notes.INTENT_EXTRA_FOLDER_ID, Notes.ID_ROOT_FOLDER);
+                intent.putExtra(Notes.INTENT_EXTRA_FOLDER_ID, viewModel.getCurrentFolderId());
                 startActivityForResult(intent, REQUEST_CODE_NEW_NODE);
             });
         }
     }
 
+    /**
+     * 处理列表项点击
+     * <p>
+     * 如果是便签，打开编辑器；如果是文件夹，进入该文件夹
+     * </p>
+     *
+     * @param note 项
+     * @param position 位置
+     */
+    private void handleItemClick(NotesRepository.NoteInfo note, int position) {
+        if (isMultiSelectMode) {
+            // 多选模式：切换选中状态
+            boolean isSelected = viewModel.getSelectedNoteIds().contains(note.getId());
+            viewModel.toggleNoteSelection(note.getId(), !isSelected);
+            if (adapter != null) {
+                adapter.setSelectedIds(viewModel.getSelectedNoteIds());
+            }
+            updateToolbarForMultiSelectMode();
+        } else {
+            // 普通模式
+            if (note.type == Notes.TYPE_FOLDER) {
+                // 文件夹：进入该文件夹
+                viewModel.enterFolder(note.getId());
+            } else {
+                // 便签：打开编辑器
+                openNoteEditor(note);
+            }
+        }
+    }
+
     /**
      * 观察ViewModel的LiveData
      */
@@ -197,6 +275,74 @@ public class NotesListActivity extends AppCompatActivity
                 }
             }
         });
+
+        // 观察文件夹路径（用于面包屑导航）
+        viewModel.getFolderPathLiveData().observe(this, new Observer<List<NotesRepository.NoteInfo>>() {
+            @Override
+            public void onChanged(List<NotesRepository.NoteInfo> path) {
+                updateBreadcrumb(path);
+            }
+        });
+
+        // 观察侧栏刷新通知
+        viewModel.getSidebarRefreshNeeded().observe(this, new Observer<Boolean>() {
+            @Override
+            public void onChanged(Boolean refreshNeeded) {
+                if (refreshNeeded != null && refreshNeeded) {
+                    // 通知侧栏刷新
+                    SidebarFragment sidebarFragment = (SidebarFragment) getSupportFragmentManager()
+                            .findFragmentById(R.id.sidebar_fragment);
+                    if (sidebarFragment != null) {
+                        sidebarFragment.refreshFolderTree();
+                    }
+                    // 重置刷新状态
+                    viewModel.getSidebarRefreshNeeded().setValue(false);
+                }
+            }
+        });
+    }
+
+    /**
+     * 更新面包屑导航
+     *
+     * @param path 文件夹路径
+     */
+    private void updateBreadcrumb(List<NotesRepository.NoteInfo> path) {
+        if (breadcrumbItems == null || path == null) {
+            return;
+        }
+
+        breadcrumbItems.removeAllViews();
+
+        for (int i = 0; i < path.size(); i++) {
+            NotesRepository.NoteInfo folder = path.get(i);
+
+            // 如果不是第一个，添加分隔符 " > "
+            if (i > 0) {
+                TextView separator = new TextView(this);
+                separator.setText(" > ");
+                separator.setTextSize(14);
+                separator.setTextColor(android.R.color.darker_gray);
+                breadcrumbItems.addView(separator);
+            }
+
+            // 创建面包屑项
+            TextView breadcrumbItem = (TextView) getLayoutInflater()
+                    .inflate(R.layout.breadcrumb_item, breadcrumbItems, false);
+            breadcrumbItem.setText(folder.title);
+
+            // 如果是当前文件夹（最后一个），高亮显示且不可点击
+            if (i == path.size() - 1) {
+                breadcrumbItem.setTextColor(getColor(R.color.primary_color));
+                breadcrumbItem.setEnabled(false);
+            } else {
+                // 其他层级可以点击跳转
+                final long targetFolderId = folder.id;
+                breadcrumbItem.setOnClickListener(v -> viewModel.enterFolder(targetFolderId));
+            }
+
+            breadcrumbItems.addView(breadcrumbItem);
+        }
     }
 
     /**
@@ -252,26 +398,36 @@ public class NotesListActivity extends AppCompatActivity
     public void onNoteItemClick(int position, long noteId) {
         Log.d(TAG, "===== onNoteItemClick CALLED =====");
         Log.d(TAG, "position: " + position + ", noteId: " + noteId);
-        
-        if (actionMode != null) {
-            Log.d(TAG, "ActionMode is active, toggling selection");
+
+        if (isMultiSelectMode) {
+            Log.d(TAG, "Multi-select mode active, toggling selection");
             NotesRepository.NoteInfo note = (NotesRepository.NoteInfo) adapter.getItem(position);
             if (note != null) {
                 boolean isSelected = viewModel.getSelectedNoteIds().contains(note.getId());
                 viewModel.toggleNoteSelection(note.getId(), !isSelected);
-                
+
                 if (adapter != null) {
                     adapter.setSelectedIds(viewModel.getSelectedNoteIds());
                 }
+                // 更新toolbar标题
+                updateToolbarForMultiSelectMode();
             }
             Log.d(TAG, "===== onNoteItemClick END (multi-select mode) =====");
         } else {
-            Log.d(TAG, "ActionMode is not active, opening editor");
+            Log.d(TAG, "Normal mode, checking item type");
             NotesRepository.NoteInfo note = (NotesRepository.NoteInfo) adapter.getItem(position);
             if (note != null) {
-                openNoteEditor(note);
+                if (note.type == Notes.TYPE_FOLDER) {
+                    // 文件夹：进入该文件夹
+                    Log.d(TAG, "Folder clicked, entering folder: " + note.getId());
+                    viewModel.enterFolder(note.getId());
+                } else {
+                    // 便签：打开编辑器
+                    Log.d(TAG, "Note clicked, opening editor");
+                    openNoteEditor(note);
+                }
             }
-            Log.d(TAG, "===== onNoteItemClick END (editor mode) =====");
+            Log.d(TAG, "===== onNoteItemClick END =====");
         }
     }
 
@@ -279,91 +435,114 @@ public class NotesListActivity extends AppCompatActivity
     public void onNoteItemLongClick(int position, long noteId) {
         Log.d(TAG, "===== onNoteItemLongClick CALLED =====");
         Log.d(TAG, "position: " + position + ", noteId: " + noteId);
-        
-        if (actionMode == null) {
-            Log.d(TAG, "Starting ActionMode manually");
-            actionMode = startSupportActionMode(new androidx.appcompat.view.ActionMode.Callback() {
-                @Override
-                public boolean onCreateActionMode(androidx.appcompat.view.ActionMode mode, Menu menu) {
-                    Log.d(TAG, "onCreateActionMode called");
-                    mode.getMenuInflater().inflate(R.menu.note_list_options, menu);
-                    return true;
-                }
-
-                @Override
-                public boolean onPrepareActionMode(androidx.appcompat.view.ActionMode mode, Menu menu) {
-                    return false;
-                }
-
-                @Override
-                public boolean onActionItemClicked(androidx.appcompat.view.ActionMode mode, MenuItem item) {
-                    Log.d(TAG, "onActionItemClicked: " + item.getTitle());
-                    int itemId = item.getItemId();
-                    
-                    if (itemId == R.id.delete) {
-                        showDeleteDialog();
-                    } else if (itemId == R.id.move) {
-                        showMoveMenu();
-                    }
-                    
-                    return true;
-                }
 
-                @Override
-                public void onDestroyActionMode(androidx.appcompat.view.ActionMode mode) {
-                    Log.d(TAG, "onDestroyActionMode called");
-                    actionMode = null;
-                    viewModel.clearSelection();
-
-                    if (adapter != null) {
-                        adapter.setSelectedIds(new java.util.HashSet<>());
-                    }
-                    adapter.notifyDataSetChanged();
-                }
-            });
-            
+        if (!isMultiSelectMode) {
+            Log.d(TAG, "Entering multi-select mode");
+            enterMultiSelectMode();
             viewModel.toggleNoteSelection(noteId, true);
-            
+
             if (adapter != null) {
                 adapter.setSelectedIds(viewModel.getSelectedNoteIds());
             }
-            
+
             updateSelectionState(position, true);
-            
+
             Log.d(TAG, "===== onNoteItemLongClick END =====");
         } else {
-            Log.d(TAG, "ActionMode already active, ignoring long click");
+            Log.d(TAG, "Multi-select mode already active, ignoring long click");
         }
     }
 
     /**
-     * 更新ActionMode标题
+     * 进入多选模式
      */
-    private void updateActionModeTitle(androidx.appcompat.view.ActionMode mode) {
-        int selectedCount = viewModel.getSelectedCount();
-        String title = getString(R.string.menu_select_title, selectedCount);
-        mode.setTitle(title);
+    private void enterMultiSelectMode() {
+        isMultiSelectMode = true;
+        // 隐藏FAB按钮
+        if (fabNewNote != null) {
+            fabNewNote.setVisibility(View.GONE);
+        }
+        // 更新toolbar为多选模式
+        updateToolbarForMultiSelectMode();
     }
 
     /**
-     * 选中状态变化回调
-     *
-     * @param mode    ActionMode 实例
-     * @param position 位置
-     * @param id      便签 ID
-     * @param checked 是否选中
+     * 退出多选模式
      */
-    public void onItemCheckedStateChanged(ActionMode mode, int position, long id, boolean checked) {
-        Log.d(TAG, "onItemCheckedStateChanged: id=" + id + ", checked=" + checked);
-        viewModel.toggleNoteSelection(id, checked);
-        
+    private void exitMultiSelectMode() {
+        isMultiSelectMode = false;
+        // 显示FAB按钮
+        if (fabNewNote != null) {
+            fabNewNote.setVisibility(View.VISIBLE);
+        }
+        // 清除选中状态
+        viewModel.clearSelection();
         if (adapter != null) {
-            adapter.setSelectedIds(viewModel.getSelectedNoteIds());
+            adapter.setSelectedIds(new java.util.HashSet<>());
+            adapter.notifyDataSetChanged();
         }
-        
-        updateActionModeTitle(mode);
+        // 更新toolbar为普通模式
+        updateToolbarForNormalMode();
     }
 
+    /**
+     * 更新Toolbar为多选模式
+     */
+    private void updateToolbarForMultiSelectMode() {
+        if (toolbar == null) return;
+
+        // 设置标题为选中数量
+        int selectedCount = viewModel.getSelectedCount();
+        String title = getString(R.string.menu_select_title, selectedCount);
+        toolbar.setTitle(title);
+
+        // 设置导航图标为返回（取消多选）
+        toolbar.setNavigationIcon(androidx.appcompat.R.drawable.abc_ic_ab_back_material);
+        toolbar.setNavigationOnClickListener(v -> exitMultiSelectMode());
+
+        // 移除普通模式的菜单（如果有）
+        toolbar.getMenu().clear();
+
+        // 直接在toolbar上添加操作按钮（不在三点菜单中）
+        Menu menu = toolbar.getMenu();
+
+        // 删除按钮
+        MenuItem deleteItem = menu.add(Menu.NONE, R.id.multi_select_delete, 1, getString(R.string.menu_delete));
+        deleteItem.setIcon(android.R.drawable.ic_menu_delete);
+        deleteItem.setShowAsAction(MenuItem.SHOW_AS_ACTION_ALWAYS);
+
+        // 移动按钮
+        MenuItem moveItem = menu.add(Menu.NONE, R.id.multi_select_move, 2, getString(R.string.menu_move));
+        moveItem.setIcon(android.R.drawable.ic_menu_sort_by_size);
+        moveItem.setShowAsAction(MenuItem.SHOW_AS_ACTION_ALWAYS);
+    }
+
+    /**
+     * 更新Toolbar为普通模式
+     */
+    private void updateToolbarForNormalMode() {
+        if (toolbar == null) return;
+
+        // 设置标题为应用名称
+        toolbar.setTitle(R.string.app_name);
+
+        // 设置导航图标为汉堡菜单
+        toolbar.setNavigationIcon(android.R.drawable.ic_menu_sort_by_size);
+        toolbar.setNavigationOnClickListener(v -> {
+            if (drawerLayout != null) {
+                drawerLayout.openDrawer(findViewById(R.id.sidebar_fragment));
+            }
+        });
+
+        // 清除多选模式菜单
+        toolbar.getMenu().clear();
+
+        // 添加普通模式菜单（如果需要）
+        // getMenuInflater().inflate(R.menu.note_list_options, menu);
+    }
+
+
+
     /**
      * 显示删除确认对话框
      */
@@ -427,8 +606,8 @@ public class NotesListActivity extends AppCompatActivity
                 Toast.makeText(this, "搜索功能开发中", Toast.LENGTH_SHORT).show();
                 return true;
             case R.id.menu_new_folder:
-                // TODO: 创建新文件夹
-                Toast.makeText(this, "创建文件夹功能开发中", Toast.LENGTH_SHORT).show();
+                // 创建新文件夹
+                showCreateFolderDialog();
                 return true;
             case R.id.menu_export_text:
                 // TODO: 导出笔记
@@ -442,6 +621,13 @@ public class NotesListActivity extends AppCompatActivity
                 // TODO: 设置功能
                 Toast.makeText(this, "设置功能开发中", Toast.LENGTH_SHORT).show();
                 return true;
+            // 多选模式菜单项
+            case R.id.multi_select_delete:
+                showDeleteDialog();
+                return true;
+            case R.id.multi_select_move:
+                showMoveMenu();
+                return true;
             default:
                 return super.onOptionsItemSelected(item);
         }
@@ -500,4 +686,152 @@ public class NotesListActivity extends AppCompatActivity
         }
         Log.d("NotesListActivity", "===== updateSelectionState END =====");
     }
+
+    // ==================== SidebarFragment.OnSidebarItemSelectedListener 实现 ====================
+
+    @Override
+    public void onFolderSelected(long folderId) {
+        // 跳转到指定文件夹
+        viewModel.enterFolder(folderId);
+        // 关闭侧栏
+        if (drawerLayout != null) {
+            drawerLayout.closeDrawer(findViewById(R.id.sidebar_fragment));
+        }
+    }
+
+    @Override
+    public void onTrashSelected() {
+        // TODO: 实现跳转到回收站
+        Log.d(TAG, "Trash selected");
+        // 关闭侧栏
+        if (drawerLayout != null) {
+            drawerLayout.closeDrawer(findViewById(R.id.sidebar_fragment));
+        }
+    }
+
+    @Override
+    public void onSyncSelected() {
+        // TODO: 实现同步功能
+        Log.d(TAG, "Sync selected");
+        Toast.makeText(this, "同步功能待实现", Toast.LENGTH_SHORT).show();
+    }
+
+    @Override
+    public void onLoginSelected() {
+        // TODO: 实现登录功能
+        Log.d(TAG, "Login selected");
+        Toast.makeText(this, "登录功能待实现", Toast.LENGTH_SHORT).show();
+    }
+
+    @Override
+    public void onExportSelected() {
+        // TODO: 实现导出功能
+        Log.d(TAG, "Export selected");
+        Toast.makeText(this, "导出功能待实现", Toast.LENGTH_SHORT).show();
+    }
+
+    @Override
+    public void onSettingsSelected() {
+        // TODO: 实现设置功能
+        Log.d(TAG, "Settings selected");
+        Toast.makeText(this, "设置功能待实现", Toast.LENGTH_SHORT).show();
+    }
+
+    @Override
+    public void onCreateFolder() {
+        // 显示创建文件夹对话框
+        showCreateFolderDialog();
+    }
+
+    /**
+     * 显示创建文件夹对话框
+     */
+    private void showCreateFolderDialog() {
+        AlertDialog.Builder builder = new AlertDialog.Builder(this);
+        builder.setTitle(R.string.dialog_create_folder_title);
+
+        final EditText input = new EditText(this);
+        input.setHint(R.string.dialog_create_folder_hint);
+        input.setFilters(new InputFilter[]{new InputFilter.LengthFilter(50)});
+
+        builder.setView(input);
+
+        builder.setPositiveButton(R.string.menu_create_folder, (dialog, which) -> {
+            String folderName = input.getText().toString().trim();
+            if (TextUtils.isEmpty(folderName)) {
+                Toast.makeText(this, R.string.error_folder_name_empty, Toast.LENGTH_SHORT).show();
+                return;
+            }
+            if (folderName.length() > 50) {
+                Toast.makeText(this, R.string.error_folder_name_too_long, Toast.LENGTH_SHORT).show();
+                return;
+            }
+
+            // 创建文件夹
+            NotesRepository repository = new NotesRepository(getContentResolver());
+            long parentId = viewModel.getCurrentFolderId();
+            if (parentId == 0) {
+                parentId = Notes.ID_ROOT_FOLDER;
+            }
+            repository.createFolder(parentId, folderName,
+                new NotesRepository.Callback<Long>() {
+                    @Override
+                    public void onSuccess(Long folderId) {
+                        runOnUiThread(() -> {
+                            Toast.makeText(NotesListActivity.this, R.string.create_folder_success, Toast.LENGTH_SHORT).show();
+                            // 刷新笔记列表
+                            viewModel.loadNotes(viewModel.getCurrentFolderId());
+                        });
+                    }
+
+                    @Override
+                    public void onError(Exception error) {
+                        runOnUiThread(() -> {
+                            Toast.makeText(NotesListActivity.this, "创建文件夹失败: " + error.getMessage(), Toast.LENGTH_SHORT).show();
+                        });
+                    }
+                });
+        });
+
+        builder.setNegativeButton(android.R.string.cancel, null);
+        builder.show();
+    }
+
+    @Override
+    public void onCloseSidebar() {
+        // 关闭侧栏
+        if (drawerLayout != null) {
+            drawerLayout.closeDrawer(findViewById(R.id.sidebar_fragment));
+        }
+    }
+
+    /**
+     * 返回键按下事件处理
+     *
+     * <p>
+     * 多选模式：退出多选模式
+     * 子文件夹：返回上一级文件夹
+     * 根文件夹：最小化应用
+     * </p>
+     */
+    @Override
+    public void onBackPressed() {
+        if (isMultiSelectMode) {
+            // 多选模式：退出多选模式
+            exitMultiSelectMode();
+        } else if (drawerLayout != null && drawerLayout.isDrawerOpen(findViewById(R.id.sidebar_fragment))) {
+            // 侧栏打开：关闭侧栏
+            drawerLayout.closeDrawer(findViewById(R.id.sidebar_fragment));
+        } else if (viewModel.getCurrentFolderId() != Notes.ID_ROOT_FOLDER &&
+                   viewModel.getCurrentFolderId() != Notes.ID_CALL_RECORD_FOLDER) {
+            // 子文件夹：返回上一级
+            if (!viewModel.navigateUp()) {
+                // 如果没有导航历史，返回根文件夹
+                viewModel.loadNotes(Notes.ID_ROOT_FOLDER);
+            }
+        } else {
+            // 根文件夹：最小化应用
+            moveTaskToBack(true);
+        }
+    }
 }

src/Notesmaster/app/src/main/java/net/micode/notes/ui/SidebarFragment.java

@@ -0,0 +1,450 @@
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.micode.notes.ui;
+
+import android.app.AlertDialog;
+import android.content.Context;
+import android.os.Bundle;
+import android.text.InputFilter;
+import android.text.TextUtils;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.view.animation.Animation;
+import android.view.animation.TranslateAnimation;
+import android.widget.EditText;
+import android.widget.ImageView;
+import android.widget.LinearLayout;
+import android.widget.TextView;
+import android.widget.Toast;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.fragment.app.Fragment;
+import androidx.lifecycle.ViewModelProvider;
+import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.recyclerview.widget.RecyclerView;
+
+import net.micode.notes.R;
+import net.micode.notes.data.Notes;
+import net.micode.notes.data.NotesRepository;
+import net.micode.notes.viewmodel.FolderListViewModel;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * 侧栏Fragment
+ * <p>
+ * 显示文件夹树、菜单项和操作按钮
+ * 提供文件夹导航、创建、展开/收起等功能
+ * </p>
+ */
+public class SidebarFragment extends Fragment {
+
+    private static final String TAG = "SidebarFragment";
+    private static final int MAX_FOLDER_NAME_LENGTH = 50;
+
+    // 视图组件
+    private RecyclerView rvFolderTree;
+    private TextView tvRootFolder;
+    private TextView menuSync;
+    private TextView menuLogin;
+    private TextView menuExport;
+    private TextView menuSettings;
+    private TextView menuTrash;
+
+    // 适配器和数据
+    private FolderTreeAdapter adapter;
+    private FolderListViewModel viewModel;
+
+    // 单击和双击检测
+    private long lastClickTime = 0;
+    private View lastClickedView = null;
+    private static final long DOUBLE_CLICK_INTERVAL = 300; // 毫秒
+
+    // 回调接口
+    private OnSidebarItemSelectedListener listener;
+
+    /**
+     * 侧栏项选择回调接口
+     */
+    public interface OnSidebarItemSelectedListener {
+        /**
+         * 跳转到指定文件夹
+         * @param folderId 文件夹ID
+         */
+        void onFolderSelected(long folderId);
+
+        /**
+         * 打开回收站
+         */
+        void onTrashSelected();
+
+        /**
+         * 同步
+         */
+        void onSyncSelected();
+
+        /**
+         * 登录
+         */
+        void onLoginSelected();
+
+        /**
+         * 导出
+         */
+        void onExportSelected();
+
+        /**
+         * 设置
+         */
+        void onSettingsSelected();
+
+        /**
+         * 创建文件夹
+         */
+        void onCreateFolder();
+
+        /**
+         * 关闭侧栏
+         */
+        void onCloseSidebar();
+    }
+
+    @Override
+    public void onAttach(@NonNull Context context) {
+        super.onAttach(context);
+        if (context instanceof OnSidebarItemSelectedListener) {
+            listener = (OnSidebarItemSelectedListener) context;
+        } else {
+            throw new RuntimeException(context.toString() + " must implement OnSidebarItemSelectedListener");
+        }
+    }
+
+    @Override
+    public void onCreate(@Nullable Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        viewModel = new ViewModelProvider(this).get(FolderListViewModel.class);
+    }
+
+    @Nullable
+    @Override
+    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container,
+                         @Nullable Bundle savedInstanceState) {
+        return inflater.inflate(R.layout.sidebar_layout, container, false);
+    }
+
+    @Override
+    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
+        super.onViewCreated(view, savedInstanceState);
+        initViews(view);
+        setupListeners();
+        observeViewModel();
+    }
+
+    /**
+     * 刷新文件夹树（供外部调用，如删除笔记后）
+     */
+    public void refreshFolderTree() {
+        if (viewModel != null) {
+            viewModel.loadFolderTree();
+        }
+    }
+
+    /**
+     * 初始化视图
+     */
+    private void initViews(View view) {
+        rvFolderTree = view.findViewById(R.id.rv_folder_tree);
+        tvRootFolder = view.findViewById(R.id.tv_root_folder);
+        menuSync = view.findViewById(R.id.menu_sync);
+        menuLogin = view.findViewById(R.id.menu_login);
+        menuExport = view.findViewById(R.id.menu_export);
+        menuSettings = view.findViewById(R.id.menu_settings);
+        menuTrash = view.findViewById(R.id.menu_trash);
+
+        // 设置RecyclerView
+        rvFolderTree.setLayoutManager(new LinearLayoutManager(requireContext()));
+        adapter = new FolderTreeAdapter(new ArrayList<>(), viewModel);
+        rvFolderTree.setAdapter(adapter);
+    }
+
+    /**
+     * 设置监听器
+     */
+    private void setupListeners() {
+        View view = getView();
+        if (view == null) return;
+
+        // 根文件夹（单击展开/收起，双击跳转）
+        setupFolderClickListener(tvRootFolder, Notes.ID_ROOT_FOLDER);
+
+        // 关闭侧栏
+        view.findViewById(R.id.btn_close_sidebar).setOnClickListener(v -> {
+            if (listener != null) {
+                listener.onCloseSidebar();
+            }
+        });
+
+        // 创建文件夹
+        view.findViewById(R.id.btn_create_folder).setOnClickListener(v -> showCreateFolderDialog());
+
+        // 菜单项
+        menuSync.setOnClickListener(v -> {
+            if (listener != null) {
+                listener.onSyncSelected();
+            }
+        });
+
+        menuLogin.setOnClickListener(v -> {
+            if (listener != null) {
+                listener.onLoginSelected();
+            }
+        });
+
+        menuExport.setOnClickListener(v -> {
+            if (listener != null) {
+                listener.onExportSelected();
+            }
+        });
+
+        menuSettings.setOnClickListener(v -> {
+            if (listener != null) {
+                listener.onSettingsSelected();
+            }
+        });
+
+        menuTrash.setOnClickListener(v -> {
+            if (listener != null) {
+                listener.onTrashSelected();
+            }
+        });
+    }
+
+    /**
+     * 设置文件夹的单击/双击监听器
+     */
+    private void setupFolderClickListener(View view, long folderId) {
+        view.setOnClickListener(v -> {
+            long currentTime = System.currentTimeMillis();
+            if (lastClickedView == view && (currentTime - lastClickTime) < DOUBLE_CLICK_INTERVAL) {
+                // 这是双击，执行跳转
+                if (listener != null && folderId != Notes.ID_ROOT_FOLDER) {
+                    listener.onFolderSelected(folderId);
+                }
+                // 重置双击状态
+                lastClickTime = 0;
+                lastClickedView = null;
+            } else {
+                // 可能是单击，延迟处理
+                lastClickTime = currentTime;
+                lastClickedView = view;
+                view.postDelayed(() -> {
+                    // 如果在延迟期间没有发生双击，则执行单击操作（展开/收起）
+                    if (System.currentTimeMillis() - lastClickTime >= DOUBLE_CLICK_INTERVAL) {
+                        toggleFolderExpand(folderId);
+                    }
+                }, DOUBLE_CLICK_INTERVAL);
+            }
+        });
+    }
+
+    /**
+     * 观察ViewModel数据变化
+     */
+    private void observeViewModel() {
+        viewModel.getFolderTree().observe(getViewLifecycleOwner(), folderItems -> {
+            if (folderItems != null) {
+                adapter.setData(folderItems);
+                adapter.notifyDataSetChanged();
+            }
+        });
+
+        viewModel.loadFolderTree();
+    }
+
+    /**
+     * 切换文件夹展开/收起状态
+     */
+    private void toggleFolderExpand(long folderId) {
+        viewModel.toggleFolderExpand(folderId);
+    }
+
+    /**
+     * 显示创建文件夹对话框
+     */
+    private void showCreateFolderDialog() {
+        AlertDialog.Builder builder = new AlertDialog.Builder(requireContext());
+        builder.setTitle(R.string.dialog_create_folder_title);
+
+        final EditText input = new EditText(requireContext());
+        input.setHint(R.string.dialog_create_folder_hint);
+        input.setFilters(new InputFilter[]{new InputFilter.LengthFilter(MAX_FOLDER_NAME_LENGTH)});
+
+        builder.setView(input);
+
+        builder.setPositiveButton(R.string.menu_create_folder, (dialog, which) -> {
+            String folderName = input.getText().toString().trim();
+            if (TextUtils.isEmpty(folderName)) {
+                Toast.makeText(requireContext(), R.string.error_folder_name_empty, Toast.LENGTH_SHORT).show();
+                return;
+            }
+            if (folderName.length() > MAX_FOLDER_NAME_LENGTH) {
+                Toast.makeText(requireContext(), R.string.error_folder_name_too_long, Toast.LENGTH_SHORT).show();
+                return;
+            }
+
+            // 创建文件夹
+            NotesRepository repository = new NotesRepository(requireContext().getContentResolver());
+            long parentId = viewModel.getCurrentFolderId();
+            if (parentId == 0) {
+                parentId = Notes.ID_ROOT_FOLDER;
+            }
+            repository.createFolder(parentId, folderName,
+                new NotesRepository.Callback<Long>() {
+                    @Override
+                    public void onSuccess(Long folderId) {
+                        if (getActivity() != null) {
+                            getActivity().runOnUiThread(() -> {
+                                Toast.makeText(requireContext(), "创建文件夹成功", Toast.LENGTH_SHORT).show();
+                                // 刷新文件夹列表
+                                viewModel.loadFolderTree();
+                            });
+                        }
+                    }
+
+                    @Override
+                    public void onError(Exception error) {
+                        if (getActivity() != null) {
+                            getActivity().runOnUiThread(() -> {
+                                Toast.makeText(requireContext(), "创建文件夹失败: " + error.getMessage(), Toast.LENGTH_SHORT).show();
+                            });
+                        }
+                    }
+                });
+        });
+
+        builder.setNegativeButton(android.R.string.cancel, null);
+        builder.show();
+    }
+
+    /**
+     * FolderTreeAdapter
+     * 文件夹树适配器，支持层级显示和展开/收起
+     */
+    private static class FolderTreeAdapter extends RecyclerView.Adapter<FolderTreeAdapter.FolderViewHolder> {
+
+        private List<FolderTreeItem> folderItems;
+        private FolderListViewModel viewModel;
+
+        public FolderTreeAdapter(List<FolderTreeItem> folderItems, FolderListViewModel viewModel) {
+            this.folderItems = folderItems;
+            this.viewModel = viewModel;
+        }
+
+        public void setData(List<FolderTreeItem> folderItems) {
+            this.folderItems = folderItems;
+        }
+
+        @NonNull
+        @Override
+        public FolderViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+            View view = LayoutInflater.from(parent.getContext())
+                    .inflate(R.layout.sidebar_folder_item, parent, false);
+            return new FolderViewHolder(view);
+        }
+
+        @Override
+        public void onBindViewHolder(@NonNull FolderViewHolder holder, int position) {
+            FolderTreeItem item = folderItems.get(position);
+            boolean isExpanded = viewModel != null && viewModel.isFolderExpanded(item.folderId);
+            holder.bind(item, isExpanded);
+        }
+
+        @Override
+        public int getItemCount() {
+            return folderItems.size();
+        }
+
+        static class FolderViewHolder extends RecyclerView.ViewHolder {
+            private View indentView;
+            private ImageView ivExpandIcon;
+            private ImageView ivFolderIcon;
+            private TextView tvFolderName;
+            private TextView tvNoteCount;
+
+            public FolderViewHolder(@NonNull View itemView) {
+                super(itemView);
+                indentView = itemView.findViewById(R.id.indent_view);
+                ivExpandIcon = itemView.findViewById(R.id.iv_expand_icon);
+                ivFolderIcon = itemView.findViewById(R.id.iv_folder_icon);
+                tvFolderName = itemView.findViewById(R.id.tv_folder_name);
+                tvNoteCount = itemView.findViewById(R.id.tv_note_count);
+            }
+
+            public void bind(FolderTreeItem item, boolean isExpanded) {
+                // 设置缩进
+                int indent = item.level * 32;
+                indentView.setLayoutParams(new LinearLayout.LayoutParams(indent, LinearLayout.LayoutParams.MATCH_PARENT));
+
+                // 设置展开/收起图标
+                if (item.hasChildren) {
+                    ivExpandIcon.setVisibility(View.VISIBLE);
+                    ivExpandIcon.setRotation(isExpanded ? 90 : 0);
+                } else {
+                    ivExpandIcon.setVisibility(View.INVISIBLE);
+                }
+
+                // 设置文件夹名称
+                tvFolderName.setText(item.name);
+
+                // 设置便签数量
+                tvNoteCount.setText(String.format(itemView.getContext()
+                        .getString(R.string.folder_note_count), item.noteCount));
+            }
+        }
+    }
+
+    /**
+     * FolderTreeItem
+     * 文件夹树项数据模型
+     */
+    public static class FolderTreeItem {
+        public long folderId;
+        public String name;
+        public int level; // 层级，0表示顶级
+        public boolean hasChildren;
+        public int noteCount;
+
+        public FolderTreeItem(long folderId, String name, int level, boolean hasChildren, int noteCount) {
+            this.folderId = folderId;
+            this.name = name;
+            this.level = level;
+            this.hasChildren = hasChildren;
+            this.noteCount = noteCount;
+        }
+    }
+
+    @Override
+    public void onDetach() {
+        super.onDetach();
+        listener = null;
+    }
+}

src/Notesmaster/app/src/main/java/net/micode/notes/viewmodel/FolderListViewModel.java

@@ -0,0 +1,269 @@
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.micode.notes.viewmodel;
+
+import android.app.Application;
+import android.database.Cursor;
+import android.net.Uri;
+
+import androidx.annotation.NonNull;
+import androidx.lifecycle.AndroidViewModel;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+import net.micode.notes.data.Notes;
+import net.micode.notes.data.NotesDatabaseHelper;
+import net.micode.notes.data.NotesDatabaseHelper.TABLE;
+import net.micode.notes.data.Notes.NoteColumns;
+import net.micode.notes.data.NotesRepository;
+import net.micode.notes.ui.SidebarFragment.FolderTreeItem;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * 文件夹列表ViewModel
+ * <p>
+ * 管理文件夹树的数据和业务逻辑
+ * 提供文件夹树的查询和构建功能
+ * </p>
+ */
+public class FolderListViewModel extends AndroidViewModel {
+
+    private MutableLiveData<List<FolderTreeItem>> folderTreeLiveData;
+    private NotesDatabaseHelper dbHelper;
+    private NotesRepository repository;
+    private long currentFolderId = Notes.ID_ROOT_FOLDER; // 当前文件夹ID
+    private Set<Long> expandedFolderIds = new HashSet<>(); // 已展开的文件夹ID集合
+
+    public FolderListViewModel(@NonNull Application application) {
+        super(application);
+        dbHelper = NotesDatabaseHelper.getInstance(application);
+        repository = new NotesRepository(application.getContentResolver());
+        folderTreeLiveData = new MutableLiveData<>();
+    }
+
+    /**
+     * 获取当前文件夹ID
+     */
+    public long getCurrentFolderId() {
+        return currentFolderId;
+    }
+
+    /**
+     * 设置当前文件夹ID
+     */
+    public void setCurrentFolderId(long folderId) {
+        this.currentFolderId = folderId;
+    }
+
+    /**
+     * 切换文件夹展开/收起状态
+     * @param folderId 文件夹ID
+     */
+    public void toggleFolderExpand(long folderId) {
+        if (expandedFolderIds.contains(folderId)) {
+            expandedFolderIds.remove(folderId);
+        } else {
+            expandedFolderIds.add(folderId);
+        }
+        // 重新加载文件夹树
+        loadFolderTree();
+    }
+
+    /**
+     * 检查文件夹是否已展开
+     * @param folderId 文件夹ID
+     * @return 是否已展开
+     */
+    public boolean isFolderExpanded(long folderId) {
+        return expandedFolderIds.contains(folderId);
+    }
+
+    /**
+     * 获取文件夹树LiveData
+     */
+    public LiveData<List<FolderTreeItem>> getFolderTree() {
+        return folderTreeLiveData;
+    }
+
+    /**
+     * 加载文件夹树数据
+     */
+    public void loadFolderTree() {
+        new Thread(() -> {
+            List<FolderTreeItem> folderTree = buildFolderTree();
+            folderTreeLiveData.postValue(folderTree);
+        }).start();
+    }
+
+    /**
+     * 构建文件夹树
+     * <p>
+     * 从数据库中查询所有文件夹，并构建层级结构
+     * </p>
+     * @return 文件夹树列表
+     */
+    private List<FolderTreeItem> buildFolderTree() {
+        // 查询所有文件夹（不包括系统文件夹）
+        List<Map<String, Object>> folders = queryAllFolders();
+
+        // 构建文件夹映射表（方便查找父文件夹）
+        Map<Long, FolderNode> folderMap = new HashMap<>();
+        List<FolderNode> rootFolders = new ArrayList<>();
+
+        // 创建文件夹节点
+        for (Map<String, Object> folder : folders) {
+            long id = (Long) folder.get(NoteColumns.ID);
+            String name = (String) folder.get(NoteColumns.SNIPPET);
+            long parentId = (Long) folder.get(NoteColumns.PARENT_ID);
+            int noteCount = ((Number) folder.get(NoteColumns.NOTES_COUNT)).intValue();
+
+            FolderNode node = new FolderNode(id, name, parentId, noteCount);
+            folderMap.put(id, node);
+
+            // 如果是顶级文件夹（父文件夹为根），添加到根列表
+            if (parentId == Notes.ID_ROOT_FOLDER) {
+                rootFolders.add(node);
+            }
+        }
+
+        // 构建父子关系
+        for (FolderNode node : folderMap.values()) {
+            if (node.parentId != Notes.ID_ROOT_FOLDER) {
+                FolderNode parent = folderMap.get(node.parentId);
+                if (parent != null) {
+                    parent.children.add(node);
+                }
+            }
+        }
+
+        // 转换为扁平列表（用于RecyclerView显示）
+        List<FolderTreeItem> folderTree = new ArrayList<>();
+        // 检查根文件夹是否展开
+        boolean rootExpanded = expandedFolderIds.contains(Notes.ID_ROOT_FOLDER);
+        buildFolderTreeList(rootFolders, folderTree, 0, rootExpanded);
+
+        return folderTree;
+    }
+
+    /**
+     * 递归构建文件夹树列表
+     * 只显示已展开文件夹的子文件夹
+     * 顶层文件夹(level=0)默认收起，需要点击"我的便签"后展开
+     * @param nodes 文件夹节点列表
+     * @param folderTree 文件夹树列表（输出）
+     * @param level 当前层级
+     * @param forceExpandChildren 是否强制展开子文件夹（用于顶层）
+     */
+    private void buildFolderTreeList(List<FolderNode> nodes, List<FolderTreeItem> folderTree, int level, boolean forceExpandChildren) {
+        for (FolderNode node : nodes) {
+            // 对于顶层文件夹，需要"我的便签"展开后才显示
+            if (level == 0 && !expandedFolderIds.contains(Notes.ID_ROOT_FOLDER) && !forceExpandChildren) {
+                continue; // 跳过顶层文件夹，因为根未展开
+            }
+
+            folderTree.add(new FolderTreeItem(
+                    node.id,
+                    node.name,
+                    level,
+                    !node.children.isEmpty(),
+                    node.noteCount
+            ));
+
+            // 只有当父文件夹在 expandedFolderIds 中时，才递归处理子文件夹
+            if (!node.children.isEmpty() && expandedFolderIds.contains(node.id)) {
+                buildFolderTreeList(node.children, folderTree, level + 1, false);
+            }
+        }
+    }
+
+    /**
+     * 查询所有文件夹
+     * @return 文件夹列表
+     */
+    private List<Map<String, Object>> queryAllFolders() {
+        List<Map<String, Object>> folders = new ArrayList<>();
+
+        // 查询所有文件夹类型的笔记
+        String selection = NoteColumns.TYPE + " = ?";
+        String[] selectionArgs = new String[]{
+                String.valueOf(Notes.TYPE_FOLDER)
+        };
+
+        Cursor cursor = null;
+        try {
+            cursor = dbHelper.getReadableDatabase().query(
+                    TABLE.NOTE,
+                    null,
+                    selection,
+                    selectionArgs,
+                    null,
+                    null,
+                    NoteColumns.MODIFIED_DATE + " DESC"
+            );
+
+            if (cursor != null) {
+                while (cursor.moveToNext()) {
+                    Map<String, Object> folder = new HashMap<>();
+                    long id = cursor.getLong(cursor.getColumnIndexOrThrow(NoteColumns.ID));
+                    String name = cursor.getString(cursor.getColumnIndexOrThrow(NoteColumns.SNIPPET));
+                    long parentId = cursor.getLong(cursor.getColumnIndexOrThrow(NoteColumns.PARENT_ID));
+                    int noteCount = cursor.getInt(cursor.getColumnIndexOrThrow(NoteColumns.NOTES_COUNT));
+
+                    folder.put(NoteColumns.ID, id);
+                    folder.put(NoteColumns.SNIPPET, name);
+                    folder.put(NoteColumns.PARENT_ID, parentId);
+                    folder.put(NoteColumns.NOTES_COUNT, noteCount);
+
+                    folders.add(folder);
+                }
+            }
+        } catch (Exception e) {
+            e.printStackTrace();
+        } finally {
+            if (cursor != null) {
+                cursor.close();
+            }
+        }
+
+        return folders;
+    }
+
+    /**
+     * FolderNode
+     * 文件夹节点，用于构建文件夹树
+     */
+    private static class FolderNode {
+        public long id;
+        public String name;
+        public long parentId;
+        public int noteCount;
+        public List<FolderNode> children = new ArrayList<>();
+
+        public FolderNode(long id, String name, long parentId, int noteCount) {
+            this.id = id;
+            this.name = name;
+            this.parentId = parentId;
+            this.noteCount = noteCount;
+        }
+    }
+}

src/Notesmaster/app/src/main/java/net/micode/notes/viewmodel/NotesListViewModel.java

@@ -58,6 +58,15 @@ public class NotesListViewModel extends ViewModel {
     // 当前文件夹ID
     private long currentFolderId = Notes.ID_ROOT_FOLDER;
 
+    // 文件夹路径LiveData（用于面包屑导航）
+    private final MutableLiveData<List<NotesRepository.NoteInfo>> folderPathLiveData = new MutableLiveData<>();
+
+    // 侧栏刷新通知LiveData（删除等操作后通知侧栏刷新）
+    private final MutableLiveData<Boolean> sidebarRefreshNeeded = new MutableLiveData<>(false);
+
+    // 文件夹导航历史（用于返回上一级）
+    private final List<Long> folderHistory = new ArrayList<>();
+
     /**
      * 构造函数
      *
@@ -98,7 +107,7 @@ public class NotesListViewModel extends ViewModel {
     /**
      * 加载笔记列表
      * <p>
-     * 从指定文件夹加载笔记列表
+     * 从指定文件夹加载笔记列表，同时加载文件夹路径用于面包屑导航
      * </p>
      *
      * @param folderId 文件夹ID，{@link Notes#ID_ROOT_FOLDER} 表示根文件夹
@@ -108,6 +117,20 @@ public class NotesListViewModel extends ViewModel {
         isLoading.postValue(true);
         errorMessage.postValue(null);
 
+        // 加载文件夹路径
+        repository.getFolderPath(folderId, new NotesRepository.Callback<List<NotesRepository.NoteInfo>>() {
+            @Override
+            public void onSuccess(List<NotesRepository.NoteInfo> path) {
+                folderPathLiveData.postValue(path);
+            }
+
+            @Override
+            public void onError(Exception error) {
+                Log.e(TAG, "Failed to load folder path", error);
+            }
+        });
+
+        // 加载笔记
         repository.getNotes(folderId, new NotesRepository.Callback<List<NotesRepository.NoteInfo>>() {
             @Override
             public void onSuccess(List<NotesRepository.NoteInfo> notes) {
@@ -349,6 +372,58 @@ public class NotesListViewModel extends ViewModel {
         this.currentFolderId = folderId;
     }
 
+    /**
+     * 获取文件夹路径LiveData
+     *
+     * @return 文件夹路径LiveData
+     */
+    public MutableLiveData<List<NotesRepository.NoteInfo>> getFolderPathLiveData() {
+        return folderPathLiveData;
+    }
+
+    /**
+     * 获取侧栏刷新通知LiveData
+     *
+     * @return 侧栏刷新通知LiveData
+     */
+    public MutableLiveData<Boolean> getSidebarRefreshNeeded() {
+        return sidebarRefreshNeeded;
+    }
+
+    /**
+     * 触发侧栏刷新
+     */
+    public void triggerSidebarRefresh() {
+        sidebarRefreshNeeded.postValue(true);
+    }
+
+    /**
+     * 进入指定文件夹
+     *
+     * @param folderId 文件夹ID
+     */
+    public void enterFolder(long folderId) {
+        // 将当前文件夹添加到历史记录
+        if (currentFolderId != Notes.ID_ROOT_FOLDER && currentFolderId != Notes.ID_CALL_RECORD_FOLDER) {
+            folderHistory.add(currentFolderId);
+        }
+        loadNotes(folderId);
+    }
+
+    /**
+     * 返回上一级文件夹
+     *
+     * @return 是否成功返回上一级
+     */
+    public boolean navigateUp() {
+        if (!folderHistory.isEmpty()) {
+            long parentFolderId = folderHistory.remove(folderHistory.size() - 1);
+            loadNotes(parentFolderId);
+            return true;
+        }
+        return false;
+    }
+
     /**
      * 清除选择状态
      * <p>

src/Notesmaster/app/src/main/res/layout/activity_main.xml

@@ -1,19 +1,37 @@
 <?xml version="1.0" encoding="utf-8"?>
-<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<androidx.drawerlayout.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
-    android:id="@+id/main"
+    android:id="@+id/drawer_layout"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
+    android:fitsSystemWindows="true"
     tools:context=".MainActivity">
 
-    <TextView
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:text="Hello World!"
-        app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintEnd_toEndOf="parent"
-        app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toTopOf="parent" />
+    <!-- 主内容区域 -->
+    <androidx.constraintlayout.widget.ConstraintLayout
+        android:id="@+id/main_content"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent">
 
-</androidx.constraintlayout.widget.ConstraintLayout>
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="Hello World!"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent" />
+
+    </androidx.constraintlayout.widget.ConstraintLayout>
+
+    <!-- 侧栏 -->
+    <fragment
+        android:id="@+id/sidebar_fragment"
+        android:name="net.micode.notes.ui.SidebarFragment"
+        android:layout_width="280dp"
+        android:layout_height="match_parent"
+        android:layout_gravity="start"
+        android:tag="sidebar" />
+
+</androidx.drawerlayout.widget.DrawerLayout>

src/Notesmaster/app/src/main/res/layout/breadcrumb_item.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  面包屑项布局
+  显示文件夹名称，支持点击和长按
+-->
+<TextView xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/tv_breadcrumb_item"
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content"
+    android:textSize="14sp"
+    android:textColor="@color/primary_color"
+    android:padding="4dp"
+    android:background="?attr/selectableItemBackground"
+    android:maxLines="1"
+    android:ellipsize="end"
+    android:maxEms="10" />

src/Notesmaster/app/src/main/res/layout/breadcrumb_layout.xml

@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  面包屑导航布局
+  显示当前文件夹路径，支持点击跳转和长按重命名
+-->
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/breadcrumb_container"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:orientation="horizontal"
+    android:paddingHorizontal="16dp"
+    android:paddingVertical="8dp"
+    android:background="@android:color/white"
+    android:gravity="center_vertical">
+
+    <!-- 面包屑项容器（动态添加） -->
+    <LinearLayout
+        android:id="@+id/breadcrumb_items"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        android:layout_weight="1"
+        android:orientation="horizontal"
+        android:gravity="center_vertical" />
+
+    <!-- 文件夹图标 -->
+    <ImageView
+        android:id="@+id/iv_folder_icon"
+        android:layout_width="24dp"
+        android:layout_height="24dp"
+        android:layout_marginStart="8dp"
+        android:src="@android:drawable/ic_menu_myplaces"
+        android:contentDescription="文件夹"
+        android:visibility="gone" />
+
+</LinearLayout>

src/Notesmaster/app/src/main/res/layout/note_edit.xml

@@ -1,43 +1,56 @@
 <?xml version="1.0" encoding="utf-8"?>
 
-<!-- Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
-
-     Licensed under the Apache License, Version 2.0 (the "License");
-     you may not use this file except in compliance with the License.
-     You may obtain a copy of the License at
-
-          http://www.apache.org/licenses/LICENSE-2.0
-
-     Unless required by applicable law or agreed to in writing, software
-     distributed under the License is distributed on an "AS IS" BASIS,
-     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-     See the License for the specific language governing permissions and
-     limitations under the License.
--->
-
-<FrameLayout
-    android:layout_width="fill_parent"
-    android:layout_height="fill_parent"
-    android:background="@drawable/list_background"
-    xmlns:android="http://schemas.android.com/apk/res/android">
-
+ <!-- Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+
+      Licensed under the Apache License, Version 2.0 (the "License");
+      you may not use this file except in compliance with the License.
+      You may obtain a copy of the License at
+
+           http://www.apache.org/licenses/LICENSE-2.0
+
+      Unless required by applicable law or agreed to in writing, software
+      distributed under the License is distributed on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+      See the License for the specific language governing permissions and
+      limitations under the License.
+ -->
+
+<!-- 统一使用Material风格：与列表页面一致 -->
+<LinearLayout
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical"
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+
+    <!-- 统一使用MaterialToolbar（与列表页面一致） -->
+    <com.google.android.material.appbar.MaterialToolbar
+        android:id="@+id/toolbar"
+        android:layout_width="match_parent"
+        android:layout_height="?attr/actionBarSize"
+        android:background="?attr/colorPrimary"
+        app:title="@string/menu_edit_note"
+        app:navigationIcon="@android:drawable/ic_menu_close_clear_cancel" />
+
+    <!-- 主内容区域 -->
     <LinearLayout
-        android:layout_width="fill_parent"
-        android:layout_height="fill_parent"
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        android:layout_weight="1"
         android:orientation="vertical">
 
         <LinearLayout
             android:id="@+id/note_title"
-            android:layout_width="fill_parent"
+            android:layout_width="match_parent"
             android:layout_height="wrap_content">
 
             <TextView
                 android:id="@+id/tv_modified_date"
-                android:layout_width="0dip"
+                android:layout_width="0dp"
                 android:layout_height="wrap_content"
                 android:layout_weight="1"
                 android:layout_gravity="left|center_vertical"
-                android:layout_marginRight="8dip"
+                android:layout_marginRight="8dp"
                 android:textAppearance="@style/TextAppearanceSecondaryItem" />
 
             <ImageView
@@ -52,8 +65,8 @@
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:layout_gravity="center_vertical"
-                android:layout_marginLeft="2dip"
-                android:layout_marginRight="8dip"
+                android:layout_marginLeft="2dp"
+                android:layout_marginRight="8dp"
                 android:textAppearance="@style/TextAppearanceSecondaryItem" />
 
             <ImageButton
@@ -65,31 +78,32 @@
 
         <LinearLayout
             android:id="@+id/sv_note_edit"
-            android:layout_width="fill_parent"
-            android:layout_height="fill_parent"
+            android:layout_width="match_parent"
+            android:layout_height="0dp"
+            android:layout_weight="1"
             android:orientation="vertical">
 
             <ImageView
-                android:layout_width="fill_parent"
-                android:layout_height="7dip"
+                android:layout_width="match_parent"
+                android:layout_height="7dp"
                 android:background="@drawable/bg_color_btn_mask" />
 
             <ScrollView
-                android:layout_width="fill_parent"
-                android:layout_height="0dip"
+                android:layout_width="match_parent"
+                android:layout_height="0dp"
                 android:layout_weight="1"
                 android:scrollbars="none"
                 android:overScrollMode="never"
                 android:layout_gravity="left|top"
-                android:fadingEdgeLength="0dip">
+                android:fadingEdgeLength="0dp">
 
                 <LinearLayout
-                    android:layout_width="fill_parent"
-                    android:layout_height="fill_parent">
+                    android:layout_width="match_parent"
+                    android:layout_height="match_parent">
 
                     <net.micode.notes.ui.NoteEditText
                         android:id="@+id/note_edit_view"
-                        android:layout_width="fill_parent"
+                        android:layout_width="match_parent"
                         android:layout_height="wrap_content"
                         android:gravity="left|top"
                         android:background="@null"
@@ -101,300 +115,302 @@
 
                     <LinearLayout
                         android:id="@+id/note_edit_list"
-                        android:layout_width="fill_parent"
+                        android:layout_width="match_parent"
                         android:layout_height="wrap_content"
                         android:orientation="vertical"
-                        android:layout_marginLeft="-10dip"
+                        android:layout_marginLeft="-10dp"
                         android:visibility="gone" />
                 </LinearLayout>
             </ScrollView>
 
             <ImageView
-                android:layout_width="fill_parent"
-                android:layout_height="7dip"
+                android:layout_width="match_parent"
+                android:layout_height="7dp"
                 android:background="@drawable/bg_color_btn_mask" />
         </LinearLayout>
-    </LinearLayout>
 
-    <ImageView
-        android:id="@+id/btn_set_bg_color"
-        android:layout_height="43dip"
-        android:layout_width="wrap_content"
-        android:background="@drawable/bg_color_btn_mask"
-        android:layout_gravity="top|right" />
+        <ImageView
+            android:id="@+id/btn_set_bg_color"
+            android:layout_height="43dp"
+            android:layout_width="wrap_content"
+            android:background="@drawable/bg_color_btn_mask"
+            android:layout_gravity="top|right" />
 
-    <LinearLayout
-        android:id="@+id/note_bg_color_selector"
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:background="@drawable/note_edit_color_selector_panel"
-        android:layout_marginTop="30dip"
-        android:layout_marginRight="8dip"
-        android:layout_gravity="top|right"
-        android:visibility="gone">
-
-        <FrameLayout
-            android:layout_width="0dip"
-            android:layout_height="match_parent"
-            android:layout_weight="1">
+        <LinearLayout
+            android:id="@+id/note_bg_color_selector"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:background="@drawable/note_edit_color_selector_panel"
+            android:layout_marginTop="30dp"
+            android:layout_marginRight="8dp"
+            android:layout_gravity="top|right"
+            android:visibility="gone">
 
-            <ImageView
-                android:id="@+id/iv_bg_yellow"
-                android:layout_width="match_parent"
-                android:layout_height="match_parent" />
+            <FrameLayout
+                android:layout_width="0dp"
+                android:layout_height="match_parent"
+                android:layout_weight="1">
 
-            <ImageView
-                android:id="@+id/iv_bg_yellow_select"
-                android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
-                android:layout_gravity="bottom|right"
-                android:layout_marginRight="5dip"
-                android:focusable="false"
-                android:visibility="gone"
-                android:src="@drawable/selected" />
-        </FrameLayout>
-
-        <FrameLayout
-            android:layout_width="0dip"
-            android:layout_height="match_parent"
-            android:layout_weight="1">
+                <ImageView
+                    android:id="@+id/iv_bg_yellow"
+                    android:layout_width="match_parent"
+                    android:layout_height="match_parent" />
 
-            <ImageView
-                android:id="@+id/iv_bg_blue"
-                android:layout_width="match_parent"
-                android:layout_height="match_parent" />
+                <ImageView
+                    android:id="@+id/iv_bg_yellow_select"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_gravity="bottom|right"
+                    android:layout_marginRight="5dp"
+                    android:focusable="false"
+                    android:visibility="gone"
+                    android:src="@drawable/selected" />
+            </FrameLayout>
+
+            <FrameLayout
+                android:layout_width="0dp"
+                android:layout_height="match_parent"
+                android:layout_weight="1">
 
-            <ImageView
-                android:id="@+id/iv_bg_blue_select"
-                android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
-                android:layout_gravity="bottom|right"
-                android:focusable="false"
-                android:visibility="gone"
-                android:layout_marginRight="3dip"
-                android:src="@drawable/selected" />
-        </FrameLayout>
-
-        <FrameLayout
-            android:layout_width="0dip"
-            android:layout_height="match_parent"
-            android:layout_weight="1">
+                <ImageView
+                    android:id="@+id/iv_bg_blue"
+                    android:layout_width="match_parent"
+                    android:layout_height="match_parent" />
 
-            <ImageView
-                android:id="@+id/iv_bg_white"
-                android:layout_width="match_parent"
-                android:layout_height="match_parent" />
+                <ImageView
+                    android:id="@+id/iv_bg_blue_select"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_gravity="bottom|right"
+                    android:focusable="false"
+                    android:visibility="gone"
+                    android:layout_marginRight="3dp"
+                    android:src="@drawable/selected" />
+            </FrameLayout>
+
+            <FrameLayout
+                android:layout_width="0dp"
+                android:layout_height="match_parent"
+                android:layout_weight="1">
 
-            <ImageView
-                android:id="@+id/iv_bg_white_select"
-                android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
-                android:layout_gravity="bottom|right"
-                android:focusable="false"
-                android:visibility="gone"
-                android:layout_marginRight="2dip"
-                android:src="@drawable/selected" />
-        </FrameLayout>
-
-        <FrameLayout
-            android:layout_width="0dip"
-            android:layout_height="match_parent"
-            android:layout_weight="1">
+                <ImageView
+                    android:id="@+id/iv_bg_white"
+                    android:layout_width="match_parent"
+                    android:layout_height="match_parent" />
 
-            <ImageView
-                android:id="@+id/iv_bg_green"
-                android:layout_width="match_parent"
-                android:layout_height="match_parent" />
+                <ImageView
+                    android:id="@+id/iv_bg_white_select"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_gravity="bottom|right"
+                    android:focusable="false"
+                    android:visibility="gone"
+                    android:layout_marginRight="2dp"
+                    android:src="@drawable/selected" />
+            </FrameLayout>
+
+            <FrameLayout
+                android:layout_width="0dp"
+                android:layout_height="match_parent"
+                android:layout_weight="1">
 
-            <ImageView
-                android:id="@+id/iv_bg_green_select"
-                android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
-                android:layout_gravity="bottom|right"
-                android:focusable="false"
-                android:visibility="gone"
-                android:src="@drawable/selected" />
-        </FrameLayout>
+                <ImageView
+                    android:id="@+id/iv_bg_green"
+                    android:layout_width="match_parent"
+                    android:layout_height="match_parent" />
 
-        <FrameLayout
-            android:layout_width="0dip"
-            android:layout_height="match_parent"
-            android:layout_weight="1">
+                <ImageView
+                    android:id="@+id/iv_bg_green_select"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_gravity="bottom|right"
+                    android:focusable="false"
+                    android:visibility="gone"
+                    android:layout_marginRight="5dp"
+                    android:src="@drawable/selected" />
+            </FrameLayout>
+
+            <FrameLayout
+                android:layout_width="0dp"
+                android:layout_height="match_parent"
+                android:layout_weight="1">
 
-            <ImageView
-                android:id="@+id/iv_bg_red"
-                android:layout_width="match_parent"
-                android:layout_height="match_parent" />
+                <ImageView
+                    android:id="@+id/iv_bg_red"
+                    android:layout_width="match_parent"
+                    android:layout_height="match_parent" />
 
-            <ImageView
-                android:id="@+id/iv_bg_red_select"
-                android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
-                android:layout_gravity="bottom|right"
-                android:focusable="false"
-                android:visibility="gone"
-                android:src="@drawable/selected" />
-        </FrameLayout>
-    </LinearLayout>
+                <ImageView
+                    android:id="@+id/iv_bg_red_select"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_gravity="bottom|right"
+                    android:focusable="false"
+                    android:visibility="gone"
+                    android:layout_marginRight="3dp"
+                    android:src="@drawable/selected" />
+            </FrameLayout>
+        </LinearLayout>
 
-    <LinearLayout
-        android:id="@+id/font_size_selector"
-        android:layout_width="fill_parent"
-        android:layout_height="wrap_content"
-        android:background="@drawable/font_size_selector_bg"
-        android:layout_gravity="bottom"
-        android:visibility="gone">
-
-        <FrameLayout
-            android:id="@+id/ll_font_small"
-            android:layout_width="0dip"
+        <LinearLayout
+            android:id="@+id/font_size_selector"
+            android:layout_width="match_parent"
             android:layout_height="wrap_content"
-            android:layout_weight="1">
+            android:background="@drawable/font_size_selector_bg"
+            android:layout_gravity="bottom"
+            android:visibility="gone">
 
-            <LinearLayout
-                android:layout_width="wrap_content"
+            <FrameLayout
+                android:id="@+id/ll_font_small"
+                android:layout_width="0dp"
                 android:layout_height="wrap_content"
-                android:orientation="vertical"
-                android:layout_gravity="center"
-                android:gravity="center">
+                android:layout_weight="1">
 
-                <ImageView
-                    android:layout_width="wrap_content"
-                    android:layout_height="wrap_content"
-                    android:src="@drawable/font_small"
-                    android:layout_marginBottom="5dip" />
-
-                <TextView
+                <LinearLayout
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
-                    android:text="@string/menu_font_small"
-                    android:textAppearance="@style/TextAppearanceUnderMenuIcon" />
-            </LinearLayout>
+                    android:orientation="vertical"
+                    android:layout_gravity="center"
+                    android:gravity="center">
 
-            <ImageView
-                android:id="@+id/iv_small_select"
-                android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
-                android:layout_gravity="bottom|right"
-                android:layout_marginRight="6dip"
-                android:layout_marginBottom="-7dip"
-                android:focusable="false"
-                android:visibility="gone"
-                android:src="@drawable/selected" />
-        </FrameLayout>
-
-        <FrameLayout
-            android:id="@+id/ll_font_normal"
-            android:layout_width="0dip"
-            android:layout_height="wrap_content"
-            android:layout_weight="1">
+                    <ImageView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:src="@drawable/font_small"
+                        android:layout_marginBottom="5dp" />
 
-            <LinearLayout
-                android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
-                android:orientation="vertical"
-                android:layout_gravity="center"
-                android:gravity="center">
+                    <TextView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:text="@string/menu_font_small"
+                        android:textAppearance="@style/TextAppearanceUnderMenuIcon" />
+                </LinearLayout>
 
                 <ImageView
+                    android:id="@+id/iv_small_select"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
-                    android:src="@drawable/font_normal"
-                    android:layout_marginBottom="5dip" />
+                    android:layout_gravity="bottom|right"
+                    android:layout_marginRight="6dp"
+                    android:layout_marginBottom="-7dp"
+                    android:focusable="false"
+                    android:visibility="gone"
+                    android:src="@drawable/selected" />
+            </FrameLayout>
+
+            <FrameLayout
+                android:id="@+id/ll_font_normal"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1">
 
-                <TextView
+                <LinearLayout
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
-                    android:text="@string/menu_font_normal"
-                    android:textAppearance="@style/TextAppearanceUnderMenuIcon" />
-            </LinearLayout>
+                    android:orientation="vertical"
+                    android:layout_gravity="center"
+                    android:gravity="center">
 
-            <ImageView
-                android:id="@+id/iv_medium_select"
-                android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
-                android:layout_gravity="bottom|right"
-                android:focusable="false"
-                android:visibility="gone"
-                android:layout_marginRight="6dip"
-                android:layout_marginBottom="-7dip"
-                android:src="@drawable/selected" />
-        </FrameLayout>
-
-        <FrameLayout
-            android:id="@+id/ll_font_large"
-            android:layout_width="0dip"
-            android:layout_height="wrap_content"
-            android:layout_weight="1">
+                    <ImageView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:src="@drawable/font_normal"
+                        android:layout_marginBottom="5dp" />
 
-            <LinearLayout
-                android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
-                android:orientation="vertical"
-                android:layout_gravity="center"
-                android:gravity="center">
+                    <TextView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:text="@string/menu_font_normal"
+                        android:textAppearance="@style/TextAppearanceUnderMenuIcon" />
+                </LinearLayout>
 
                 <ImageView
+                    android:id="@+id/iv_medium_select"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
-                    android:src="@drawable/font_large"
-                    android:layout_marginBottom="5dip" />
+                    android:layout_gravity="bottom|right"
+                    android:focusable="false"
+                    android:visibility="gone"
+                    android:layout_marginRight="6dp"
+                    android:layout_marginBottom="-7dp"
+                    android:src="@drawable/selected" />
+            </FrameLayout>
+
+            <FrameLayout
+                android:id="@+id/ll_font_large"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1">
 
-                <TextView
+                <LinearLayout
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
-                    android:text="@string/menu_font_large"
-                    android:textAppearance="@style/TextAppearanceUnderMenuIcon" />
-            </LinearLayout>
+                    android:orientation="vertical"
+                    android:layout_gravity="center"
+                    android:gravity="center">
 
-            <ImageView
-                android:id="@+id/iv_large_select"
-                android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
-                android:layout_gravity="bottom|right"
-                android:focusable="false"
-                android:visibility="gone"
-                android:layout_marginRight="6dip"
-                android:layout_marginBottom="-7dip"
-                android:src="@drawable/selected" />
-        </FrameLayout>
-
-        <FrameLayout
-            android:id="@+id/ll_font_super"
-            android:layout_width="0dip"
-            android:layout_height="wrap_content"
-            android:layout_weight="1">
+                    <ImageView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:src="@drawable/font_large"
+                        android:layout_marginBottom="5dp" />
 
-            <LinearLayout
-                android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
-                android:orientation="vertical"
-                android:layout_gravity="center"
-                android:gravity="center">
+                    <TextView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:text="@string/menu_font_large"
+                        android:textAppearance="@style/TextAppearanceUnderMenuIcon" />
+                </LinearLayout>
 
                 <ImageView
+                    android:id="@+id/iv_large_select"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
-                    android:src="@drawable/font_super"
-                    android:layout_marginBottom="5dip" />
+                    android:layout_gravity="bottom|right"
+                    android:focusable="false"
+                    android:visibility="gone"
+                    android:layout_marginRight="6dp"
+                    android:layout_marginBottom="-7dp"
+                    android:src="@drawable/selected" />
+            </FrameLayout>
+
+            <FrameLayout
+                android:id="@+id/ll_font_super"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1">
 
-                <TextView
+                <LinearLayout
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
-                    android:text="@string/menu_font_super"
-                    android:textAppearance="@style/TextAppearanceUnderMenuIcon" />
-            </LinearLayout>
+                    android:orientation="vertical"
+                    android:layout_gravity="center"
+                    android:gravity="center">
 
-            <ImageView
-                android:id="@+id/iv_super_select"
-                android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
-                android:layout_gravity="bottom|right"
-                android:focusable="false"
-                android:visibility="gone"
-                android:layout_marginRight="6dip"
-                android:layout_marginBottom="-7dip"
-                android:src="@drawable/selected" />
-        </FrameLayout>
+                    <ImageView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:src="@drawable/font_super"
+                        android:layout_marginBottom="5dp" />
+
+                    <TextView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:text="@string/menu_font_super"
+                        android:textAppearance="@style/TextAppearanceUnderMenuIcon" />
+                </LinearLayout>
+
+                <ImageView
+                    android:id="@+id/iv_super_select"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_gravity="bottom|right"
+                    android:focusable="false"
+                    android:visibility="gone"
+                    android:layout_marginRight="6dp"
+                    android:layout_marginBottom="-7dp"
+                    android:src="@drawable/selected" />
+            </FrameLayout>
+        </LinearLayout>
     </LinearLayout>
-</FrameLayout>
+</LinearLayout>

src/Notesmaster/app/src/main/res/layout/note_list.xml

@@ -1,80 +1,101 @@
 <?xml version="1.0" encoding="utf-8"?>
 
-<!-- Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
-
-     Licensed under the Apache License, Version 2.0 (the "License");
-     you may not use this file except in compliance with the License.
-     You may obtain a copy of the License at
-
-          http://www.apache.org/licenses/LICENSE-2.0
-
-     Unless required by applicable law or agreed to in writing, software
-     distributed under the License is distributed on an "AS IS" BASIS,
-     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-     See the License for the specific language governing permissions and
-     limitations under the License.
--->
-
-<!-- 现代化布局：使用 CoordinatorLayout + AppBarLayout + Toolbar -->
-<androidx.coordinatorlayout.widget.CoordinatorLayout
-    xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
-    android:layout_width="match_parent"
-    android:layout_height="match_parent"
-    android:background="@drawable/list_background">
-
-    <!-- AppBarLayout：替代传统 ActionBar -->
-    <com.google.android.material.appbar.AppBarLayout
-        android:id="@+id/appbar"
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        android:theme="@style/ThemeOverlay.Material3.ActionBar">
-
-        <!-- Toolbar：现代替代 ActionBar 的标准组件 -->
-        <com.google.android.material.appbar.MaterialToolbar
-            android:id="@+id/toolbar"
-            android:layout_width="match_parent"
-            android:layout_height="?attr/actionBarSize"
-            app:title="@string/app_name"
-            app:layout_scrollFlags="scroll|enterAlways|snap" />
-
-    </com.google.android.material.appbar.AppBarLayout>
-
-    <!-- 便签列表：使用 NestedScrollView 包裹 ListView 以支持滚动 -->
-    <androidx.core.widget.NestedScrollView
-        android:layout_width="match_parent"
-        android:layout_height="match_parent"
-        android:fillViewport="true"
-        app:layout_behavior="@string/appbar_scrolling_view_behavior">
-
-        <LinearLayout
-            android:layout_width="match_parent"
-            android:layout_height="wrap_content"
-            android:orientation="vertical">
-
-            <!-- 便签列表 -->
-            <ListView
-                android:id="@+id/notes_list"
-                android:layout_width="match_parent"
-                android:layout_height="wrap_content"
-                android:minHeight="200dp"
-                android:cacheColorHint="@null"
-                android:listSelector="@android:color/transparent"
-                android:divider="@null"
-                android:fadingEdge="@null" />
-
-        </LinearLayout>
-
-    </androidx.core.widget.NestedScrollView>
-
-    <!-- 悬浮按钮：替代原来的底部按钮 -->
-    <com.google.android.material.floatingactionbutton.FloatingActionButton
-        android:id="@+id/btn_new_note"
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:layout_gravity="bottom|end"
-        android:layout_margin="16dp"
-        android:contentDescription="@string/notelist_menu_new"
-        app:srcCompat="@android:drawable/ic_input_add" />
-
-</androidx.coordinatorlayout.widget.CoordinatorLayout>
+ <!-- Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+
+      Licensed under the Apache License, Version 2.0 (the "License");
+      you may not use this file except in compliance with the License.
+      You may obtain a copy of the License at
+
+           http://www.apache.org/licenses/LICENSE-2.0
+
+      Unless required by applicable law or agreed to in writing, software
+      distributed under the License is distributed on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+      See the License for the specific language governing permissions and
+      limitations under the License.
+ -->
+
+ <!-- DrawerLayout：支持侧栏滑动 -->
+<androidx.drawerlayout.widget.DrawerLayout
+     xmlns:android="http://schemas.android.com/apk/res/android"
+     xmlns:app="http://schemas.android.com/apk/res-auto"
+     android:id="@+id/drawer_layout"
+     android:layout_width="match_parent"
+     android:layout_height="match_parent"
+     android:background="@drawable/list_background">
+
+     <!-- 主内容区域 -->
+     <androidx.coordinatorlayout.widget.CoordinatorLayout
+         android:layout_width="match_parent"
+         android:layout_height="match_parent">
+
+         <!-- AppBarLayout：替代传统 ActionBar -->
+         <com.google.android.material.appbar.AppBarLayout
+             android:id="@+id/appbar"
+             android:layout_width="match_parent"
+             android:layout_height="wrap_content"
+             android:theme="@style/ThemeOverlay.Material3.ActionBar">
+
+             <!-- Toolbar：现代替代 ActionBar 的标准组件，带汉堡菜单按钮 -->
+             <com.google.android.material.appbar.MaterialToolbar
+                 android:id="@+id/toolbar"
+                 android:layout_width="match_parent"
+                 android:layout_height="?attr/actionBarSize"
+                 app:title="@string/app_name"
+                 app:navigationIcon="@android:drawable/ic_menu_sort_by_size"
+                 app:layout_scrollFlags="scroll|enterAlways|snap" />
+
+       </com.google.android.material.appbar.AppBarLayout>
+
+           <!-- 便签列表：使用 NestedScrollView 包裹 ListView 以支持滚动 -->
+          <androidx.core.widget.NestedScrollView
+              android:layout_width="match_parent"
+              android:layout_height="match_parent"
+              android:fillViewport="true"
+              app:layout_behavior="@string/appbar_scrolling_view_behavior">
+
+              <LinearLayout
+                  android:layout_width="match_parent"
+                  android:layout_height="wrap_content"
+                  android:orientation="vertical">
+
+                  <!-- 面包屑导航：显示当前文件夹路径（在列表上方） -->
+                  <include layout="@layout/breadcrumb_layout" />
+
+                  <!-- 便签列表 -->
+                  <ListView
+                      android:id="@+id/notes_list"
+                      android:layout_width="match_parent"
+                      android:layout_height="wrap_content"
+                      android:minHeight="200dp"
+                      android:cacheColorHint="@null"
+                      android:listSelector="@android:color/transparent"
+                      android:divider="@null"
+                      android:fadingEdge="@null" />
+
+              </LinearLayout>
+
+          </androidx.core.widget.NestedScrollView>
+
+         <!-- 悬浮按钮：替代原来的底部按钮 -->
+         <com.google.android.material.floatingactionbutton.FloatingActionButton
+             android:id="@+id/btn_new_note"
+             android:layout_width="wrap_content"
+             android:layout_height="wrap_content"
+             android:layout_gravity="bottom|end"
+             android:layout_margin="16dp"
+             android:contentDescription="@string/notelist_menu_new"
+             app:srcCompat="@android:drawable/ic_input_add" />
+
+     </androidx.coordinatorlayout.widget.CoordinatorLayout>
+
+     <!-- 侧栏 -->
+     <fragment
+         android:id="@+id/sidebar_fragment"
+         android:name="net.micode.notes.ui.SidebarFragment"
+         android:layout_width="280dp"
+         android:layout_height="match_parent"
+         android:layout_gravity="start"
+         android:tag="sidebar" />
+
+</androidx.drawerlayout.widget.DrawerLayout>

src/Notesmaster/app/src/main/res/layout/sidebar_folder_item.xml

@@ -0,0 +1,73 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  侧栏文件夹项布局
+  支持展开/收起图标、文件夹图标、名称和数量
+-->
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:orientation="horizontal"
+    android:padding="12dp"
+    android:background="?attr/selectableItemBackground"
+    android:gravity="center_vertical">
+
+    <!-- 缩进（用于子文件夹） -->
+    <View
+        android:id="@+id/indent_view"
+        android:layout_width="0dp"
+        android:layout_height="match_parent" />
+
+    <!-- 展开/收起箭头 -->
+    <ImageView
+        android:id="@+id/iv_expand_icon"
+        android:layout_width="24dp"
+        android:layout_height="24dp"
+        android:src="@android:drawable/arrow_down_float"
+        android:contentDescription="展开/收起"
+        android:scaleType="centerInside"
+        android:rotation="0" />
+
+    <!-- 文件夹图标 -->
+    <ImageView
+        android:id="@+id/iv_folder_icon"
+        android:layout_width="32dp"
+        android:layout_height="32dp"
+        android:layout_marginStart="8dp"
+        android:src="@android:drawable/ic_menu_myplaces"
+        android:contentDescription="文件夹"
+        android:scaleType="centerInside" />
+
+    <!-- 文件夹名称和数量 -->
+    <LinearLayout
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        android:layout_weight="1"
+        android:layout_marginStart="12dp"
+        android:orientation="vertical"
+        android:gravity="center_vertical">
+
+        <!-- 文件夹名称 -->
+        <TextView
+            android:id="@+id/tv_folder_name"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:textSize="16sp"
+            android:textColor="@android:color/black"
+            android:ellipsize="end"
+            android:maxLines="1"
+            tools:text="工作" />
+
+        <!-- 文件夹数量 -->
+        <TextView
+            android:id="@+id/tv_note_count"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:textSize="12sp"
+            android:textColor="@android:color/darker_gray"
+            android:ellipsize="end"
+            android:maxLines="1"
+            tools:text="5个便签" />
+    </LinearLayout>
+
+</LinearLayout>

src/Notesmaster/app/src/main/res/layout/sidebar_layout.xml

@@ -0,0 +1,174 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  侧栏布局文件
+  包含文件夹树、菜单项、操作栏和回收站入口
+-->
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:id="@+id/sidebar_container"
+    android:layout_width="280dp"
+    android:layout_height="match_parent"
+    android:layout_gravity="start"
+    android:orientation="vertical"
+    android:background="@android:color/white"
+    android:elevation="8dp">
+
+    <!-- 操作栏 -->
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="horizontal"
+        android:padding="16dp"
+        android:background="@android:color/white"
+        android:elevation="4dp">
+
+        <!-- 关闭按钮 -->
+        <ImageButton
+            android:id="@+id/btn_close_sidebar"
+            android:layout_width="40dp"
+            android:layout_height="40dp"
+            android:background="?attr/selectableItemBackgroundBorderless"
+            android:contentDescription="关闭侧栏"
+            android:padding="8dp"
+            android:src="@android:drawable/ic_menu_close_clear_cancel" />
+
+        <View
+            android:layout_width="0dp"
+            android:layout_height="match_parent"
+            android:layout_weight="1" />
+
+        <!-- 创建文件夹按钮 -->
+        <ImageButton
+            android:id="@+id/btn_create_folder"
+            android:layout_width="40dp"
+            android:layout_height="40dp"
+            android:background="?attr/selectableItemBackgroundBorderless"
+            android:contentDescription="创建文件夹"
+            android:padding="8dp"
+            android:src="@android:drawable/ic_input_add" />
+    </LinearLayout>
+
+    <!-- 分隔线 -->
+    <View
+        android:layout_width="match_parent"
+        android:layout_height="1dp"
+        android:background="@android:color/darker_gray" />
+
+    <!-- 根文件夹（始终显示） -->
+    <TextView
+        android:id="@+id/tv_root_folder"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:padding="16dp"
+        android:drawableStart="@android:drawable/ic_menu_myplaces"
+        android:drawablePadding="12dp"
+        android:text="@string/root_folder_name"
+        android:textSize="16sp"
+        android:textColor="@android:color/black"
+        android:background="?attr/selectableItemBackground"
+        android:gravity="center_vertical" />
+
+    <!-- 分隔线 -->
+    <View
+        android:layout_width="match_parent"
+        android:layout_height="1dp"
+        android:background="@android:color/darker_gray" />
+
+    <!-- 文件夹树列表 -->
+    <androidx.recyclerview.widget.RecyclerView
+        android:id="@+id/rv_folder_tree"
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        android:layout_weight="1"
+        android:padding="8dp"
+        android:clipToPadding="false" />
+
+    <!-- 分隔线 -->
+    <View
+        android:layout_width="match_parent"
+        android:layout_height="1dp"
+        android:background="@android:color/darker_gray" />
+
+    <!-- 菜单项 -->
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="vertical">
+
+        <!-- 同步 -->
+        <TextView
+            android:id="@+id/menu_sync"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:padding="16dp"
+            android:drawableStart="@android:drawable/ic_menu_upload"
+            android:drawablePadding="12dp"
+            android:text="@string/menu_sync"
+            android:textSize="16sp"
+            android:textColor="@android:color/black"
+            android:background="?attr/selectableItemBackground"
+            android:gravity="center_vertical" />
+
+        <!-- 登录 -->
+        <TextView
+            android:id="@+id/menu_login"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:padding="16dp"
+            android:drawableStart="@android:drawable/ic_lock_lock"
+            android:drawablePadding="12dp"
+            android:text="@string/menu_login"
+            android:textSize="16sp"
+            android:textColor="@android:color/black"
+            android:background="?attr/selectableItemBackground"
+            android:gravity="center_vertical" />
+
+        <!-- 导出 -->
+        <TextView
+            android:id="@+id/menu_export"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:padding="16dp"
+            android:drawableStart="@android:drawable/ic_menu_save"
+            android:drawablePadding="12dp"
+            android:text="@string/menu_export"
+            android:textSize="16sp"
+            android:textColor="@android:color/black"
+            android:background="?attr/selectableItemBackground"
+            android:gravity="center_vertical" />
+
+        <!-- 设置 -->
+        <TextView
+            android:id="@+id/menu_settings"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:padding="16dp"
+            android:drawableStart="@android:drawable/ic_menu_preferences"
+            android:drawablePadding="12dp"
+            android:text="@string/menu_settings"
+            android:textSize="16sp"
+            android:textColor="@android:color/black"
+            android:background="?attr/selectableItemBackground"
+            android:gravity="center_vertical" />
+    </LinearLayout>
+
+    <!-- 分隔线 -->
+    <View
+        android:layout_width="match_parent"
+        android:layout_height="1dp"
+        android:background="@android:color/darker_gray" />
+
+    <!-- 回收站（固定底部） -->
+    <TextView
+        android:id="@+id/menu_trash"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:padding="16dp"
+        android:drawableStart="@android:drawable/ic_menu_delete"
+        android:drawablePadding="12dp"
+        android:text="@string/menu_trash"
+        android:textSize="16sp"
+        android:textColor="@android:color/black"
+        android:background="?attr/selectableItemBackground"
+        android:gravity="center_vertical" />
+</LinearLayout>

src/Notesmaster/app/src/main/res/menu/note_list_multi_select.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  多选模式的Toolbar菜单
+  包含删除、移动、取消选项
+-->
+<menu xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <item
+        android:id="@+id/multi_select_delete"
+        android:icon="@android:drawable/ic_menu_delete"
+        android:title="@string/menu_delete"
+        android:showAsAction="ifRoom" />
+
+    <item
+        android:id="@+id/multi_select_move"
+        android:icon="@android:drawable/ic_menu_sort_by_size"
+        android:title="@string/menu_move"
+        android:showAsAction="ifRoom" />
+
+</menu>

src/Notesmaster/app/src/main/res/menu/note_list_toolbar_multi.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  多选模式的Toolbar布局
+  包含删除、移动按钮
+-->
+<menu xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <item
+        android:id="@+id/action_delete"
+        android:icon="@android:drawable/ic_menu_delete"
+        android:title="@string/menu_delete"
+        android:showAsAction="always"
+        android:orderInCategory="1" />
+
+    <item
+        android:id="@+id/action_move"
+        android:icon="@android:drawable/ic_menu_sort_by_size"
+        android:title="@string/menu_move"
+        android:showAsAction="always"
+        android:orderInCategory="2" />
+
+</menu>

src/Notesmaster/app/src/main/res/values/strings.xml

@@ -137,4 +137,19 @@
     <string name="empty_notes_hint">暂无便签，点击右下角按钮创建</string>
     <string name="empty_notes_icon">空便签图标</string>
     <string name="menu_edit_note">Edit note</string>
+    <!-- Sidebar strings -->
+    <string name="root_folder_name">我的便签</string>
+    <string name="sidebar_close">关闭侧栏</string>
+    <string name="sidebar_create_folder">创建文件夹</string>
+    <string name="menu_login">登录</string>
+    <string name="menu_export">导出</string>
+    <string name="menu_settings">设置</string>
+    <string name="menu_trash">回收站</string>
+    <string name="folder_note_count">%1$d个便签</string>
+    <string name="dialog_create_folder_title">创建文件夹</string>
+    <string name="dialog_create_folder_hint">请输入文件夹名称</string>
+    <string name="error_folder_name_empty">文件夹名称不能为空</string>
+    <string name="error_folder_name_too_long">文件夹名称不能超过50个字符</string>
+    <string name="error_folder_name_exists">该文件夹已存在</string>
+    <string name="create_folder_success">创建文件夹成功</string>
 </resources>

src/Notesmaster/app/src/main/res/values/themes.xml

@@ -7,4 +7,11 @@
     </style>
 
     <style name="Theme.Notesmaster" parent="Base.Theme.Notesmaster" />
+
+    <!-- NoteEditActivity使用的主题：统一使用Material3风格 -->
+    <style name="Theme.Notesmaster.Edit" parent="Theme.Material3.Light.NoActionBar">
+        <item name="colorPrimary">@color/primary_color</item>
+        <item name="colorOnPrimary">@color/on_primary_color</item>
+        <item name="android:statusBarColor">@color/primary_color</item>
+    </style>
 </resources>

src/Notesmaster/app/src/test/java/net/micode/notes/data/NotesRepositoryTest.java

@@ -26,6 +26,7 @@ import org.mockito.Mock;
 import org.mockito.junit.MockitoJUnitRunner;
 
 import net.micode.notes.model.Note;
+import net.micode.notes.data.NotesRepository.NoteInfo;
 
 import java.util.List;
 
@@ -77,9 +78,9 @@ public class NotesRepositoryTest {
         long folderId = Notes.ID_ROOT_FOLDER;
 
         // Act
-        repository.getNotes(folderId, new NotesRepository.Callback<List<Note>>() {
+        repository.getNotes(folderId, new NotesRepository.Callback<List<NoteInfo>>() {
             @Override
-            public void onSuccess(List<Note> result) {
+            public void onSuccess(List<NoteInfo> result) {
                 assertNotNull("Notes list should not be null", result);
                 // Mock返回空列表，实际应用中会有数据
                 assertTrue("Notes count should be >= 0", result.size() >= 0);
@@ -171,9 +172,9 @@ public class NotesRepositoryTest {
         String keyword = "测试";
 
         // Act
-        repository.searchNotes(keyword, new NotesRepository.Callback<List<Note>>() {
+        repository.searchNotes(keyword, new NotesRepository.Callback<List<NoteInfo>>() {
             @Override
-            public void onSuccess(List<Note> result) {
+            public void onSuccess(List<NoteInfo> result) {
                 assertNotNull("Search results should not be null", result);
                 assertTrue("Search results count should be >= 0", result.size() >= 0);
             }
@@ -194,9 +195,9 @@ public class NotesRepositoryTest {
         String keyword = "";
 
         // Act
-        repository.searchNotes(keyword, new NotesRepository.Callback<List<Note>>() {
+        repository.searchNotes(keyword, new NotesRepository.Callback<List<NoteInfo>>() {
             @Override
-            public void onSuccess(List<Note> result) {
+            public void onSuccess(List<NoteInfo> result) {
                 assertNotNull("Search results should not be null", result);
                 // 空关键字应返回空列表
                 assertEquals("Search results should be empty", 0, result.size());
@@ -238,9 +239,9 @@ public class NotesRepositoryTest {
     @Test
     public void testGetFolders() {
         // Act
-        repository.getFolders(new NotesRepository.Callback<List<Note>>() {
+        repository.getFolders(new NotesRepository.Callback<List<NoteInfo>>() {
             @Override
-            public void onSuccess(List<Note> result) {
+            public void onSuccess(List<NoteInfo> result) {
                 assertNotNull("Folders should not be null", result);
                 assertTrue("Folders count should be >= 0", result.size() >= 0);
             }

src/Notesmaster/gradle/libs.versions.toml

@@ -7,6 +7,7 @@ appcompat = "1.6.1"
 material = "1.10.0"
 activity = "1.8.0"
 constraintlayout = "2.1.4"
+mockito = "4.11.0"
 
 [libraries]
 junit = { group = "junit", name = "junit", version.ref = "junit" }
@@ -16,6 +17,8 @@ appcompat = { group = "androidx.appcompat", name = "appcompat", version.ref = "a
 material = { group = "com.google.android.material", name = "material", version.ref = "material" }
 activity = { group = "androidx.activity", name = "activity", version.ref = "activity" }
 constraintlayout = { group = "androidx.constraintlayout", name = "constraintlayout", version.ref = "constraintlayout" }
+mockito-core = { group = "org.mockito", name = "mockito-core", version.ref = "mockito" }
+mockito-junit = { group = "org.mockito", name = "mockito-junit-jupiter", version.ref = "mockito" }
 
 [plugins]
 android-application = { id = "com.android.application", version.ref = "agp" }