src/main/java/net/micode/notes/data/Notes.java

@@ -99,6 +99,16 @@ public class Notes {
      * 组件类型：4x4大小的便签组件
      */
     public static final int TYPE_WIDGET_4X            = 1;
+    
+    /**
+     * 锁类型：便签锁
+     */
+    public static final int LOCK_TYPE_NOTE            = 0;
+    
+    /**
+     * 锁类型：文件夹锁
+     */
+    public static final int LOCK_TYPE_FOLDER          = 1;
 
     /**
      * 数据类型常量类，定义了不同类型便签的数据项类型
@@ -234,6 +244,26 @@ public class Notes {
          * <P> 0表示未置顶，1表示置顶 </P>
          */
         public static final String PINNED = "pinned";
+        
+        /**
+         * 是否上锁
+         * <P> 类型: INTEGER </P>
+         * <P> 0表示未上锁，1表示上锁 </P>
+         */
+        public static final String IS_LOCKED = "is_locked";
+        
+        /**
+         * 加密后的密码
+         * <P> 类型: TEXT </P>
+         */
+        public static final String LOCK_PASSWORD = "lock_password";
+        
+        /**
+         * 锁类型
+         * <P> 类型: INTEGER </P>
+         * <P> 0表示便签锁，1表示文件夹锁 </P>
+         */
+        public static final String LOCK_TYPE = "lock_type";
     }
 
     public interface DataColumns {

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

@@ -35,7 +35,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
     // 数据库文件名
     private static final String DB_NAME = "note.db";
     // 数据库版本号，用于升级控制
-    private static final int DB_VERSION = 5;
+    private static final int DB_VERSION = 6;
 
     /**
      * 数据库表名常量定义
@@ -75,7 +75,10 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
                     NoteColumns.ORIGIN_PARENT_ID + " INTEGER NOT NULL DEFAULT 0," +
                     NoteColumns.GTASK_ID + " TEXT NOT NULL DEFAULT ''," +
                     NoteColumns.VERSION + " INTEGER NOT NULL DEFAULT 0," +
-                    NoteColumns.PINNED + " INTEGER NOT NULL DEFAULT 0" +
+                    NoteColumns.PINNED + " INTEGER NOT NULL DEFAULT 0," +
+                    NoteColumns.IS_LOCKED + " INTEGER NOT NULL DEFAULT 0," +
+                    NoteColumns.LOCK_PASSWORD + " TEXT NOT NULL DEFAULT ''," +
+                    NoteColumns.LOCK_TYPE + " INTEGER NOT NULL DEFAULT 0" +
                     ")";
 
     /**
@@ -385,6 +388,12 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
             oldVersion++;
         }
 
+        // 版本5升级到版本6：添加锁相关字段
+        if (oldVersion == 5) {
+            upgradeToV6(db);
+            oldVersion++;
+        }
+
         // 如果需要，重新创建触发器
         if (reCreateTriggers) {
             reCreateNoteTableTriggers(db);
@@ -445,4 +454,17 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.PINNED
                 + " INTEGER NOT NULL DEFAULT 0");
     }
+
+    /**
+     * 升级到版本6：添加锁相关字段，用于便签和文件夹上锁功能
+     * @param db 数据库实例
+     */
+    private void upgradeToV6(SQLiteDatabase db) {
+        db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.IS_LOCKED
+                + " INTEGER NOT NULL DEFAULT 0");
+        db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.LOCK_PASSWORD
+                + " TEXT NOT NULL DEFAULT ''");
+        db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.LOCK_TYPE
+                + " INTEGER NOT NULL DEFAULT 0");
+    }
 }

src/main/java/net/micode/notes/model/WorkingNote.java

@@ -504,6 +504,19 @@ public class WorkingNote {
         }
     }
 
+    /**
+     * 设置笔记的基本属性值
+     * <p>
+     * 直接调用内部Note对象的setNoteValue方法，用于更新笔记的基本属性。
+     * </p>
+     * 
+     * @param key 属性键名，对应NoteColumns中的字段名
+     * @param value 属性值
+     */
+    public void setNoteValue(String key, String value) {
+        mNote.setNoteValue(key, value);
+    }
+
     /**
      * 设置笔记内容
      * <p>

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

@@ -48,6 +48,10 @@ import android.widget.CompoundButton;
 import android.widget.CompoundButton.OnCheckedChangeListener;
 import android.widget.EditText;
 import android.widget.ImageView;
+import android.database.Cursor;
+import android.content.ContentResolver;
+import net.micode.notes.data.Notes;
+import net.micode.notes.data.Notes.NoteColumns;
 import android.widget.LinearLayout;
 import android.widget.TextView;
 import android.widget.Toast;
@@ -671,6 +675,12 @@ public class NoteEditActivity extends Activity implements OnClickListener,
             case R.id.menu_delete_remind:
                 mWorkingNote.setAlertDate(0, false);
                 break;
+            case R.id.menu_lock:
+                showPasswordDialogForLock();
+                break;
+            case R.id.menu_unlock:
+                showPasswordDialogForUnlock();
+                break;
             default:
                 break;
         }
@@ -709,6 +719,139 @@ public class NoteEditActivity extends Activity implements OnClickListener,
         context.startActivity(intent);
     }
 
+    /**
+     * 显示密码输入对话框用于锁定笔记
+     * <p>
+     * 该方法用于显示一个密码输入对话框，让用户输入密码来锁定当前编辑的笔记
+     * </p>
+     */
+    private void showPasswordDialogForLock() {
+        final EditText passwordEditText = new EditText(this);
+        passwordEditText.setHint(R.string.hint_enter_password);
+        passwordEditText.setInputType(android.text.InputType.TYPE_CLASS_TEXT | android.text.InputType.TYPE_TEXT_VARIATION_PASSWORD);
+
+        new AlertDialog.Builder(this)
+                .setTitle(R.string.dialog_enter_password)
+                .setView(passwordEditText)
+                .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
+                    @Override
+                    public void onClick(DialogInterface dialog, int which) {
+                        String password = passwordEditText.getText().toString();
+                        if (!TextUtils.isEmpty(password)) {
+                            lockCurrentNote(password);
+                        }
+                    }
+                })
+                .setNegativeButton(android.R.string.cancel, null)
+                .show();
+    }
+
+    /**
+     * 显示密码输入对话框用于解锁笔记
+     * <p>
+     * 该方法用于显示一个密码输入对话框，让用户输入密码来解锁当前编辑的笔记
+     * </p>
+     */
+    private void showPasswordDialogForUnlock() {
+        final EditText passwordEditText = new EditText(this);
+        passwordEditText.setHint(R.string.hint_enter_password);
+        passwordEditText.setInputType(android.text.InputType.TYPE_CLASS_TEXT | android.text.InputType.TYPE_TEXT_VARIATION_PASSWORD);
+
+        new AlertDialog.Builder(this)
+                .setTitle(R.string.dialog_enter_password)
+                .setView(passwordEditText)
+                .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
+                    @Override
+                    public void onClick(DialogInterface dialog, int which) {
+                        String password = passwordEditText.getText().toString();
+                        if (!TextUtils.isEmpty(password)) {
+                            unlockCurrentNote(password);
+                        }
+                    }
+                })
+                .setNegativeButton(android.R.string.cancel, null)
+                .show();
+    }
+
+    /**
+     * 锁定当前笔记
+     * <p>
+     * 该方法用于锁定当前编辑的笔记，更新其锁定状态、密码和锁定类型
+     * </p>
+     * @param password 用于锁定的密码
+     */
+    private void lockCurrentNote(String password) {
+        // 设置锁定状态为1（已锁定）
+        mWorkingNote.setNoteValue(NoteColumns.IS_LOCKED, "1");
+        // 设置加密后的密码
+        mWorkingNote.setNoteValue(NoteColumns.LOCK_PASSWORD, encryptPassword(password));
+        // 设置锁定类型为笔记类型
+        mWorkingNote.setNoteValue(NoteColumns.LOCK_TYPE, String.valueOf(Notes.LOCK_TYPE_NOTE));
+        // 保存笔记
+        saveNote();
+        // 显示提示信息
+        Toast.makeText(this, getString(R.string.message_note_locked), Toast.LENGTH_SHORT).show();
+    }
+
+    /**
+     * 解锁当前笔记
+     * <p>
+     * 该方法用于解锁当前编辑的笔记，更新其锁定状态和密码
+     * </p>
+     * @param password 用于解锁的密码
+     */
+    private void unlockCurrentNote(String password) {
+        // 使用ContentResolver直接查询数据库获取加密密码
+        String[] projection = {NoteColumns.LOCK_PASSWORD};
+        String selection = NoteColumns.ID + "=?";
+        String[] selectionArgs = {String.valueOf(mWorkingNote.getNoteId())};
+        
+        Cursor cursor = getContentResolver().query(Notes.CONTENT_NOTE_URI, projection, selection, selectionArgs, null);
+        String encryptedPassword = null;
+        
+        if (cursor != null && cursor.moveToFirst()) {
+            encryptedPassword = cursor.getString(0);
+            cursor.close();
+        }
+        
+        // 验证密码是否正确
+        if (encryptedPassword != null && encryptedPassword.equals(encryptPassword(password))) {
+            // 密码正确，设置锁定状态为0（未锁定）
+            mWorkingNote.setNoteValue(NoteColumns.IS_LOCKED, "0");
+            // 清空密码
+            mWorkingNote.setNoteValue(NoteColumns.LOCK_PASSWORD, "");
+            // 保存笔记
+            saveNote();
+            // 显示提示信息
+            Toast.makeText(this, getString(R.string.message_note_unlocked), Toast.LENGTH_SHORT).show();
+        } else {
+            // 密码错误，显示错误信息
+            Toast.makeText(this, getString(R.string.error_wrong_password), Toast.LENGTH_SHORT).show();
+        }
+    }
+
+    /**
+     * 加密密码
+     * <p>
+     * 该方法使用Base64和ANDROID_ID对密码进行加密
+     * </p>
+     * @param password 原始密码
+     * @return 加密后的密码
+     */
+    private String encryptPassword(String password) {
+        try {
+            // 获取设备的ANDROID_ID作为加密密钥
+            String androidId = android.provider.Settings.Secure.getString(getContentResolver(),
+                    android.provider.Settings.Secure.ANDROID_ID);
+            // 使用简单的加密算法：将密码与ANDROID_ID拼接后进行Base64编码
+            String combined = password + androidId;
+            return android.util.Base64.encodeToString(combined.getBytes(), android.util.Base64.DEFAULT);
+        } catch (Exception e) {
+            Log.e(TAG, "Password encryption failed", e);
+            return password; // 加密失败时返回原始密码
+        }
+    }
+
     /**
      * 创建新笔记
      * <p>

src/main/java/net/micode/notes/ui/NoteItemData.java

@@ -54,6 +54,9 @@ public class NoteItemData {
         NoteColumns.WIDGET_ID,
         NoteColumns.WIDGET_TYPE,
         NoteColumns.PINNED,
+        NoteColumns.IS_LOCKED,
+        NoteColumns.LOCK_PASSWORD,
+        NoteColumns.LOCK_TYPE,
     };
 
     /**
@@ -120,6 +123,21 @@ public class NoteItemData {
      * 查询结果中置顶状态列的索引
      */
     private static final int PINNED_COLUMN                = 12;
+    
+    /**
+     * 查询结果中锁定状态列的索引
+     */
+    private static final int IS_LOCKED_COLUMN             = 13;
+    
+    /**
+     * 查询结果中锁定密码列的索引
+     */
+    private static final int LOCK_PASSWORD_COLUMN         = 14;
+    
+    /**
+     * 查询结果中锁定类型列的索引
+     */
+    private static final int LOCK_TYPE_COLUMN             = 15;
 
     /**
      * 笔记ID
@@ -131,6 +149,21 @@ public class NoteItemData {
      */
     private boolean mPinned;
     
+    /**
+     * 锁定状态
+     */
+    private boolean mIsLocked;
+    
+    /**
+     * 锁定密码
+     */
+    private String mLockPassword;
+    
+    /**
+     * 锁定类型
+     */
+    private int mLockType;
+    
     /**
      * 提醒日期
      */
@@ -242,6 +275,9 @@ public class NoteItemData {
         mWidgetId = cursor.getInt(WIDGET_ID_COLUMN);
         mWidgetType = cursor.getInt(WIDGET_TYPE_COLUMN);
         mPinned = (cursor.getInt(PINNED_COLUMN) > 0) ? true : false;
+        mIsLocked = (cursor.getInt(IS_LOCKED_COLUMN) > 0) ? true : false;
+        mLockPassword = cursor.getString(LOCK_PASSWORD_COLUMN);
+        mLockType = cursor.getInt(LOCK_TYPE_COLUMN);
 
         mPhoneNumber = "";
         if (mParentId == Notes.ID_CALL_RECORD_FOLDER) {
@@ -475,6 +511,54 @@ public class NoteItemData {
     public void setPinned(boolean pinned) {
         mPinned = pinned;
     }
+    
+    /**
+     * 获取锁定状态
+     * @return 锁定状态，true表示已锁定，false表示未锁定
+     */
+    public boolean isLocked() {
+        return mIsLocked;
+    }
+    
+    /**
+     * 设置锁定状态
+     * @param locked 锁定状态，true表示锁定，false表示解锁
+     */
+    public void setLocked(boolean locked) {
+        mIsLocked = locked;
+    }
+    
+    /**
+     * 获取锁定密码
+     * @return 锁定密码
+     */
+    public String getLockPassword() {
+        return mLockPassword;
+    }
+    
+    /**
+     * 设置锁定密码
+     * @param password 锁定密码
+     */
+    public void setLockPassword(String password) {
+        mLockPassword = password;
+    }
+    
+    /**
+     * 获取锁定类型
+     * @return 锁定类型，0表示笔记，1表示文件夹
+     */
+    public int getLockType() {
+        return mLockType;
+    }
+    
+    /**
+     * 设置锁定类型
+     * @param type 锁定类型，0表示笔记，1表示文件夹
+     */
+    public void setLockType(int type) {
+        mLockType = type;
+    }
 
     /**
      * 获取笔记类型（静态方法）

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

@@ -115,6 +115,127 @@ public class NotesListActivity extends Activity implements OnClickListener, OnIt
      */
     private enum ListEditState {
         NOTE_LIST, SUB_FOLDER, CALL_RECORD_FOLDER
+    }
+
+    /**
+     * 显示密码输入对话框
+     * <p>
+     * 该方法用于显示一个密码输入对话框，让用户输入密码来锁定选中的笔记或文件夹
+     * </p>
+     */
+    private void showPasswordDialog() {
+        final EditText passwordEditText = new EditText(this);
+        passwordEditText.setHint(R.string.hint_enter_password);
+        passwordEditText.setInputType(android.text.InputType.TYPE_CLASS_TEXT | android.text.InputType.TYPE_TEXT_VARIATION_PASSWORD);
+
+        new AlertDialog.Builder(this)
+                .setTitle(R.string.dialog_enter_password)
+                .setView(passwordEditText)
+                .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
+                    @Override
+                    public void onClick(DialogInterface dialog, int which) {
+                        String password = passwordEditText.getText().toString();
+                        if (!TextUtils.isEmpty(password)) {
+                            toggleLockedStatus(password);
+                        }
+                    }
+                })
+                .setNegativeButton(android.R.string.cancel, null)
+                .show();
+    }
+
+    /**
+     * 切换锁定状态
+     * <p>
+     * 该方法用于切换选中笔记或文件夹的锁定状态，使用异步任务处理数据库操作
+     * </p>
+     * @param password 用于锁定的密码
+     */
+    private void toggleLockedStatus(final String password) {
+        final HashSet<Long> selectedIds = mNotesListAdapter.getSelectedItemIds();
+        final int selectedCount = mNotesListAdapter.getSelectedCount();
+
+        new AsyncTask<Void, Void, Integer>() {
+            protected Integer doInBackground(Void... unused) {
+                int finalLockedStatus = -1; // 默认为-1，表示未处理
+                for (Long noteId : selectedIds) {
+                    // 查询当前便签的锁定状态
+                    Cursor cursor = mContentResolver.query(Notes.CONTENT_NOTE_URI,
+                            new String[]{NoteColumns.IS_LOCKED},
+                            NoteColumns.ID + "=?",
+                            new String[]{String.valueOf(noteId)},
+                            null);
+
+                    if (cursor != null && cursor.moveToFirst()) {
+                        int currentLocked = cursor.getInt(0);
+                        // 切换锁定状态
+                        int newLocked = currentLocked == 1 ? 0 : 1;
+                        finalLockedStatus = newLocked; // 保存最终锁定状态
+
+                        ContentValues values = new ContentValues();
+                        values.put(NoteColumns.IS_LOCKED, newLocked);
+
+                        if (newLocked == 1) {
+                            // 如果是锁定操作，设置密码和锁定类型
+                            values.put(NoteColumns.LOCK_PASSWORD, encryptPassword(password));
+                            // 判断是笔记还是文件夹
+                            Cursor typeCursor = mContentResolver.query(Notes.CONTENT_NOTE_URI,
+                                    new String[]{NoteColumns.TYPE},
+                                    NoteColumns.ID + "=?",
+                                    new String[]{String.valueOf(noteId)},
+                                    null);
+                            if (typeCursor != null && typeCursor.moveToFirst()) {
+                                int type = typeCursor.getInt(0);
+                                values.put(NoteColumns.LOCK_TYPE, type == Notes.TYPE_FOLDER ? Notes.LOCK_TYPE_FOLDER : Notes.LOCK_TYPE_NOTE);
+                                typeCursor.close();
+                            }
+                        } else {
+                            // 如果是解锁操作，清空密码
+                            values.put(NoteColumns.LOCK_PASSWORD, "");
+                        }
+
+                        mContentResolver.update(Notes.CONTENT_NOTE_URI,
+                                values,
+                                NoteColumns.ID + "=?",
+                                new String[]{String.valueOf(noteId)});
+
+                        cursor.close();
+                    }
+                }
+                return finalLockedStatus;
+            }
+
+            @Override
+            protected void onPostExecute(Integer finalLockedStatus) {
+                String message = finalLockedStatus == 1 ? getString(R.string.message_note_locked) : getString(R.string.message_note_unlocked);
+                Toast.makeText(NotesListActivity.this, message, Toast.LENGTH_SHORT).show();
+                // 重新查询数据，更新列表
+                startAsyncNotesListQuery();
+                mModeCallBack.finishActionMode();
+            }
+        }.execute();
+    }
+
+    /**
+     * 加密密码
+     * <p>
+     * 该方法使用Base64和ANDROID_ID对密码进行加密
+     * </p>
+     * @param password 原始密码
+     * @return 加密后的密码
+     */
+    private String encryptPassword(String password) {
+        try {
+            // 获取设备的ANDROID_ID作为加密密钥
+            String androidId = android.provider.Settings.Secure.getString(getContentResolver(),
+                    android.provider.Settings.Secure.ANDROID_ID);
+            // 使用简单的加密算法：将密码与ANDROID_ID拼接后进行Base64编码
+            String combined = password + androidId;
+            return android.util.Base64.encodeToString(combined.getBytes(), android.util.Base64.DEFAULT);
+        } catch (Exception e) {
+            Log.e(TAG, "Password encryption failed", e);
+            return password; // 加密失败时返回原始密码
+        }
     };
 
     /** 当前列表编辑状态 */
@@ -201,6 +322,19 @@ public class NotesListActivity extends Activity implements OnClickListener, OnIt
          * Insert an introduction when user firstly use this application
          */
         setAppInfoFromRawRes();
+        
+        // 注册Android 13+的返回键回调
+        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.TIRAMISU) {
+            getOnBackInvokedDispatcher().registerOnBackInvokedCallback(
+                    android.window.OnBackInvokedDispatcher.PRIORITY_DEFAULT,
+                    new android.window.OnBackInvokedCallback() {
+                        @Override
+                        public void onBackInvoked() {
+                            handleBackPress();
+                        }
+                    }
+            );
+        }
     }
 
     /**
@@ -366,6 +500,11 @@ public class NotesListActivity extends Activity implements OnClickListener, OnIt
             if (pinMenu != null) {
                 pinMenu.setOnMenuItemClickListener(this);
             }
+            // 添加锁定菜单初始化
+            MenuItem lockMenu = menu.findItem(R.id.lock);
+            if (lockMenu != null) {
+                lockMenu.setOnMenuItemClickListener(this);
+            }
             mActionMode = mode;
             mNotesListAdapter.setChoiceMode(true);
             mNotesListView.setLongClickable(false);
@@ -528,6 +667,9 @@ public class NotesListActivity extends Activity implements OnClickListener, OnIt
                 case R.id.pin:
                     togglePinnedStatus();
                     break;
+                case R.id.lock:
+                    showPasswordDialog();
+                    break;
                 default:
                     return false;
             }
@@ -862,11 +1004,72 @@ public class NotesListActivity extends Activity implements OnClickListener, OnIt
      * </p>
      * @param data 要打开的笔记数据项
      */
-    private void openNode(NoteItemData data) {
-        Intent intent = new Intent(this, NoteEditActivity.class);
-        intent.setAction(Intent.ACTION_VIEW);
-        intent.putExtra(Intent.EXTRA_UID, data.getId());
-        this.startActivityForResult(intent, REQUEST_CODE_OPEN_NODE);
+    private void openNode(final NoteItemData data) {
+        // 检查笔记是否被锁定
+        if (data.isLocked()) {
+            final EditText passwordEditText = new EditText(this);
+            passwordEditText.setHint(R.string.hint_enter_password);
+            passwordEditText.setInputType(android.text.InputType.TYPE_CLASS_TEXT | android.text.InputType.TYPE_TEXT_VARIATION_PASSWORD);
+
+            new AlertDialog.Builder(this)
+                    .setTitle(R.string.dialog_enter_password)
+                    .setView(passwordEditText)
+                    .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
+                        @Override
+                        public void onClick(DialogInterface dialog, int which) {
+                            String password = passwordEditText.getText().toString();
+                            if (!TextUtils.isEmpty(password)) {
+                                verifyPasswordAndOpenNote(data.getId(), password);
+                            }
+                        }
+                    })
+                    .setNegativeButton(android.R.string.cancel, null)
+                    .show();
+        } else {
+            // 未锁定，直接打开笔记
+            Intent intent = new Intent(this, NoteEditActivity.class);
+            intent.setAction(Intent.ACTION_VIEW);
+            intent.putExtra(Intent.EXTRA_UID, data.getId());
+            startActivityForResult(intent, REQUEST_CODE_OPEN_NODE);
+        }
+    }
+
+    /**
+     * 验证密码并打开笔记
+     * <p>
+     * 该方法完成以下工作：
+     * 1. 查询笔记的加密密码
+     * 2. 验证密码是否正确
+     * 3. 如果正确，打开笔记；否则显示错误信息
+     * </p>
+     * @param noteId 笔记ID
+     * @param password 用户输入的密码
+     */
+    private void verifyPasswordAndOpenNote(final long noteId, String password) {
+        // 查询笔记的加密密码
+        String[] projection = {NoteColumns.LOCK_PASSWORD};
+        String selection = NoteColumns.ID + "=?";
+        String[] selectionArgs = {String.valueOf(noteId)};
+        
+        Cursor cursor = getContentResolver().query(Notes.CONTENT_NOTE_URI, projection, selection, selectionArgs, null);
+        String encryptedPassword = null;
+        
+        if (cursor != null && cursor.moveToFirst()) {
+            encryptedPassword = cursor.getString(0);
+            cursor.close();
+        }
+        
+        // 验证密码是否正确
+        if (encryptedPassword != null && encryptedPassword.equals(encryptPassword(password))) {
+            // 密码正确，打开笔记
+            Intent intent = new Intent(this, NoteEditActivity.class);
+            intent.setAction(Intent.ACTION_VIEW);
+            intent.putExtra(Intent.EXTRA_UID, noteId);
+            startActivityForResult(intent, REQUEST_CODE_OPEN_NODE);
+        } else {
+            // 密码错误，显示错误信息
+            Toast.makeText(this, getString(R.string.error_wrong_password), Toast.LENGTH_SHORT).show();
+        }
     }
 
     /**
@@ -1052,8 +1255,7 @@ public class NotesListActivity extends Activity implements OnClickListener, OnIt
      * 3. 如果在根文件夹中，调用默认的返回处理
      * </p>
      */
-    @Override
-    public void onBackPressed() {
+    private void handleBackPress() {
         switch (mState) {
             case SUB_FOLDER:
                 mCurrentFolderId = Notes.ID_ROOT_FOLDER;
@@ -1076,6 +1278,11 @@ public class NotesListActivity extends Activity implements OnClickListener, OnIt
         }
     }
 
+    @Override
+    public void onBackPressed() {
+        handleBackPress();
+    }
+
     /**
      * 更新部件
      * <p>

src/main/res/menu/note_edit.xml

@@ -49,4 +49,12 @@
     <item
         android:id="@+id/menu_delete_remind"
         android:title="@string/menu_remove_remind" />
+        
+    <item
+        android:id="@+id/menu_lock"
+        android:title="@string/menu_lock" />
+        
+    <item
+        android:id="@+id/menu_unlock"
+        android:title="@string/menu_unlock" />
 </menu>

src/main/res/menu/note_list_options.xml

@@ -33,4 +33,9 @@
         android:id="@+id/pin"
         android:title="@string/menu_pin"
         android:showAsAction="always|withText" />
+        
+    <item
+        android:id="@+id/lock"
+        android:title="@string/menu_lock"
+        android:showAsAction="always|withText" />
 </menu>

src/main/res/values/strings.xml

@@ -50,6 +50,13 @@
     <string name="menu_move">Move to folder</string>
     <string name="menu_pin">Pin</string>
     <string name="menu_unpin">Unpin</string>
+    <string name="menu_lock">Lock</string>
+    <string name="menu_unlock">Unlock</string>
+    <string name="dialog_enter_password">Enter Password</string>
+    <string name="hint_enter_password">Please enter password</string>
+    <string name="error_wrong_password">Incorrect password</string>
+    <string name="message_note_locked">Note locked successfully</string>
+    <string name="message_note_unlocked">Note unlocked successfully</string>
     <string name="menu_select_title">%d selected</string>
     <string name="menu_select_none">Nothing selected, the operation is invalid</string>
     <string name="menu_select_all">Select all</string>