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

@@ -265,6 +265,13 @@ public class Notes {
          */
         public static final String LOCK_TYPE = "lock_type";
         
+        /**
+         * 密码提示
+         * <P> 类型: TEXT </P>
+         * <P> 用于帮助用户记忆密码的提示信息 </P>
+         */
+        public static final String LOCK_HINT = "lock_hint";
+        
         /**
          * 便签或文件夹被删除的时间
          * <P> 类型: INTEGER (long) </P>

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 = 7;
+    private static final int DB_VERSION = 8;
 
     /**
      * 数据库表名常量定义
@@ -79,6 +79,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
                     NoteColumns.IS_LOCKED + " INTEGER NOT NULL DEFAULT 0," +
                     NoteColumns.LOCK_PASSWORD + " TEXT NOT NULL DEFAULT ''," +
                     NoteColumns.LOCK_TYPE + " INTEGER NOT NULL DEFAULT 0," +
+                    NoteColumns.LOCK_HINT + " TEXT NOT NULL DEFAULT ''," +
                     NoteColumns.DELETED_DATE + " INTEGER NOT NULL DEFAULT 0" +
                     ")";
 
@@ -425,6 +426,12 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
             oldVersion++;
         }
 
+        // 版本7升级到版本8：添加密码提示字段
+        if (oldVersion == 7) {
+            upgradeToV8(db);
+            oldVersion++;
+        }
+
         // 如果需要，重新创建触发器
         if (reCreateTriggers) {
             reCreateNoteTableTriggers(db);
@@ -530,4 +537,14 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
                 "  WHERE " + NoteColumns.ID + "=new." + NoteColumns.ID + ";" +
                 " END");
     }
+    
+    /**
+     * 升级到版本8：添加密码提示字段，用于密码记忆辅助
+     * @param db 数据库实例
+     */
+    private void upgradeToV8(SQLiteDatabase db) {
+        // 添加LOCK_HINT字段，用于存储密码提示
+        db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.LOCK_HINT
+                + " TEXT NOT NULL DEFAULT ''");
+    }
 }

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

@@ -46,6 +46,9 @@ import android.view.View.OnClickListener;
 import android.view.WindowManager;
 import android.widget.Button;
 import android.widget.CheckBox;
+import android.widget.LinearLayout;
+import android.widget.TextView;
+import android.util.TypedValue;
 import android.widget.CompoundButton;
 import android.widget.CompoundButton.OnCheckedChangeListener;
 import android.widget.EditText;
@@ -172,6 +175,9 @@ public class NoteEditActivity extends Activity implements OnClickListener,
     /** 笔记编辑面板 */
     private View mNoteEditorPanel;
 
+    /** 字符统计显示文本框 */
+    private TextView mTvCharCount;
+
     /** 工作笔记对象，用于处理笔记数据 */
     private WorkingNote mWorkingNote;
 
@@ -350,6 +356,8 @@ public class NoteEditActivity extends Activity implements OnClickListener,
             mNoteEditor.setText(getHighlightQueryResult(htmlContent, mUserQuery));
             mNoteEditor.setSelection(mNoteEditor.getText().length());
         }
+        // 初始化字符统计显示
+        updateCharCount();
         for (Integer id : sBgSelectorSelectionMap.keySet()) {
             findViewById(sBgSelectorSelectionMap.get(id)).setVisibility(View.GONE);
         }
@@ -480,7 +488,9 @@ public class NoteEditActivity extends Activity implements OnClickListener,
         mNoteHeaderHolder.ibSetBgColor = (ImageButton) findViewById(R.id.btn_set_bg_color);
         mNoteHeaderHolder.ibSetBgColor.setOnClickListener(this);
         mNoteEditor = (NoteEditText) findViewById(R.id.note_edit_view);
+        mNoteEditor.setOnTextViewChangeListener(this);
         mNoteEditorPanel = findViewById(R.id.sv_note_edit);
+        mTvCharCount = (TextView) findViewById(R.id.tv_char_count);
         mNoteBgColorSelector = findViewById(R.id.note_bg_color_selector);
         for (int id : sBgSelectorBtnsMap.keySet()) {
             ImageView iv = (ImageView) findViewById(id);
@@ -768,6 +778,9 @@ public class NoteEditActivity extends Activity implements OnClickListener,
             case R.id.menu_unlock:
                 showPasswordDialogForUnlock();
                 break;
+            case R.id.menu_change_password:
+                showChangePasswordDialog();
+                break;
             case R.id.menu_note_template:
                 openTemplateSelector();
                 break;
@@ -812,23 +825,41 @@ public class NoteEditActivity extends Activity implements OnClickListener,
     /**
      * 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
+     * 该方法用于显示一个密码输入对话框，让用户输入密码和密码提示来锁定当前编辑的笔记
      * </p>
      */
     private void showPasswordDialogForLock() {
+        // 创建布局并添加密码输入框
+        LinearLayout layout = new LinearLayout(this);
+        layout.setOrientation(LinearLayout.VERTICAL);
+        layout.setPadding(60, 40, 60, 40);
+        layout.setPadding(60, 40, 60, 40);
+        // 设置子视图间距
+        LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
+                LinearLayout.LayoutParams.MATCH_PARENT,
+                LinearLayout.LayoutParams.WRAP_CONTENT);
+        params.setMargins(0, 0, 0, 20); // 底部外边距作为间距
+
         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);
+        layout.addView(passwordEditText);
+
+        // 添加密码提示输入框
+        final EditText hintEditText = new EditText(this);
+        hintEditText.setHint(R.string.hint_enter_password_hint);
+        layout.addView(hintEditText);
 
         new AlertDialog.Builder(this)
                 .setTitle(R.string.dialog_enter_password)
-                .setView(passwordEditText)
+                .setView(layout)
                 .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
                     @Override
                     public void onClick(DialogInterface dialog, int which) {
                         String password = passwordEditText.getText().toString();
+                        String hint = hintEditText.getText().toString();
                         if (!TextUtils.isEmpty(password)) {
-                            lockCurrentNote(password);
+                            lockCurrentNote(password, hint);
                         }
                     }
                 })
@@ -843,13 +874,50 @@ public class NoteEditActivity extends Activity implements OnClickListener,
      * </p>
      */
     private void showPasswordDialogForUnlock() {
+        // 查询当前笔记的密码提示
+        String[] projection = {NoteColumns.LOCK_HINT};
+        String selection = NoteColumns.ID + "=?";
+        String[] selectionArgs = {String.valueOf(mWorkingNote.getNoteId())};
+        
+        Cursor cursor = getContentResolver().query(Notes.CONTENT_NOTE_URI, projection, selection, selectionArgs, null);
+        String lockHint = null;
+        if (cursor != null && cursor.moveToFirst()) {
+            lockHint = cursor.getString(0);
+            cursor.close();
+        }
+
+        // 创建布局并添加密码输入框
+        LinearLayout layout = new LinearLayout(this);
+        layout.setOrientation(LinearLayout.VERTICAL);
+        layout.setPadding(60, 40, 60, 40);
+
+        // 创建布局参数，用于设置子视图间距
+        LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
+                LinearLayout.LayoutParams.MATCH_PARENT,
+                LinearLayout.LayoutParams.WRAP_CONTENT);
+        params.setMargins(0, 0, 0, 20); // 底部外边距作为间距
+
         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);
+        layout.addView(passwordEditText, params);
+
+        // 如果有密码提示，显示提示信息
+        if (!TextUtils.isEmpty(lockHint)) {
+            TextView hintTextView = new TextView(this);
+            hintTextView.setText(getString(R.string.password_hint_prefix) + lockHint);
+            hintTextView.setTextColor(getResources().getColor(R.color.secondary_text_dark));
+            hintTextView.setTextSize(TypedValue.COMPLEX_UNIT_SP, 14);
+            // 提示文本不需要底部间距
+            LinearLayout.LayoutParams hintParams = new LinearLayout.LayoutParams(
+                    LinearLayout.LayoutParams.MATCH_PARENT,
+                    LinearLayout.LayoutParams.WRAP_CONTENT);
+            layout.addView(hintTextView, hintParams);
+        }
 
         new AlertDialog.Builder(this)
                 .setTitle(R.string.dialog_enter_password)
-                .setView(passwordEditText)
+                .setView(layout)
                 .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
                     @Override
                     public void onClick(DialogInterface dialog, int which) {
@@ -866,17 +934,20 @@ public class NoteEditActivity extends Activity implements OnClickListener,
     /**
      * 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
+     * 该方法用于锁定当前编辑的笔记，更新其锁定状态、密码、密码提示和锁定类型
      * </p>
      * @param password 用于锁定的密码
+     * @param hint 用于帮助记忆密码的提示
      */
-    private void lockCurrentNote(String password) {
+    private void lockCurrentNote(String password, String hint) {
         // 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));
+        // 设置密码提示
+        mWorkingNote.setNoteValue(NoteColumns.LOCK_HINT, hint);
         // 保存笔记
         saveNote();
         // 显示提示信息
@@ -941,6 +1012,97 @@ public class NoteEditActivity extends Activity implements OnClickListener,
             return password; // 加密失败时返回原始密码
         }
     }
+    
+    /**
+     * 显示修改密码对话框
+     * <p>
+     * 该方法用于显示一个修改密码对话框，让用户输入旧密码、新密码和新的密码提示
+     * </p>
+     */
+    private void showChangePasswordDialog() {
+        // 创建布局并添加输入框
+        LinearLayout layout = new LinearLayout(this);
+        layout.setOrientation(LinearLayout.VERTICAL);
+        layout.setPadding(60, 40, 60, 40);
+
+        // 创建布局参数，用于设置子视图间距
+        LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
+                LinearLayout.LayoutParams.MATCH_PARENT,
+                LinearLayout.LayoutParams.WRAP_CONTENT);
+        params.setMargins(0, 0, 0, 20); // 底部外边距作为间距
+
+        // 旧密码输入框
+        final EditText oldPasswordEditText = new EditText(this);
+        oldPasswordEditText.setHint(R.string.hint_enter_password);
+        oldPasswordEditText.setInputType(android.text.InputType.TYPE_CLASS_TEXT | android.text.InputType.TYPE_TEXT_VARIATION_PASSWORD);
+        layout.addView(oldPasswordEditText, params);
+
+        // 新密码输入框
+        final EditText newPasswordEditText = new EditText(this);
+        newPasswordEditText.setHint(R.string.hint_enter_password);
+        newPasswordEditText.setInputType(android.text.InputType.TYPE_CLASS_TEXT | android.text.InputType.TYPE_TEXT_VARIATION_PASSWORD);
+        layout.addView(newPasswordEditText, params);
+
+        // 新密码提示输入框
+        final EditText newHintEditText = new EditText(this);
+        newHintEditText.setHint(R.string.hint_enter_password_hint);
+        layout.addView(newHintEditText);
+
+        new AlertDialog.Builder(this)
+                .setTitle(R.string.menu_change_password)
+                .setView(layout)
+                .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
+                    @Override
+                    public void onClick(DialogInterface dialog, int which) {
+                        String oldPassword = oldPasswordEditText.getText().toString();
+                        String newPassword = newPasswordEditText.getText().toString();
+                        String newHint = newHintEditText.getText().toString();
+                        if (!TextUtils.isEmpty(oldPassword) && !TextUtils.isEmpty(newPassword)) {
+                            changePassword(oldPassword, newPassword, newHint);
+                        }
+                    }
+                })
+                .setNegativeButton(android.R.string.cancel, null)
+                .show();
+    }
+    
+    /**
+     * 修改密码
+     * <p>
+     * 该方法用于修改当前笔记的密码，需要验证旧密码，验证通过后更新新密码和密码提示
+     * </p>
+     * @param oldPassword 旧密码
+     * @param newPassword 新密码
+     * @param newHint 新的密码提示
+     */
+    private void changePassword(String oldPassword, String newPassword, String newHint) {
+        // 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();
+        }
+        
+        // 验证旧密码是否正确
+        if (encryptedPassword != null && encryptedPassword.equals(encryptPassword(oldPassword))) {
+            // 旧密码正确，更新新密码和密码提示
+            mWorkingNote.setNoteValue(NoteColumns.LOCK_PASSWORD, encryptPassword(newPassword));
+            mWorkingNote.setNoteValue(NoteColumns.LOCK_HINT, newHint);
+            // 保存笔记
+            saveNote();
+            // 显示提示信息
+            Toast.makeText(this, getString(R.string.message_password_changed), Toast.LENGTH_SHORT).show();
+        } else {
+            // 旧密码错误，显示错误信息
+            Toast.makeText(this, getString(R.string.error_wrong_password), Toast.LENGTH_SHORT).show();
+        }
+    }
 
     /**
      * 创建新笔记
@@ -1229,6 +1391,15 @@ public class NoteEditActivity extends Activity implements OnClickListener,
         } else {
             mEditTextList.getChildAt(index).findViewById(R.id.cb_edit_item).setVisibility(View.GONE);
         }
+        // 更新字符统计
+        updateCharCount();
+    }
+
+    /**
+     * 当文本内容变化时，更新字符统计
+     */
+    public void onContentChange() {
+        updateCharCount();
     }
 
     /**
@@ -1382,6 +1553,45 @@ public class NoteEditActivity extends Activity implements OnClickListener,
         showToast(resId, Toast.LENGTH_SHORT);
     }
 
+    /**
+     * 计算字符串中的有效字符数（不包括空格、换行符等空白字符）
+     * @param text 要计算的字符串
+     * @return 有效字符数
+     */
+    private int countValidCharacters(String text) {
+        if (TextUtils.isEmpty(text)) {
+            return 0;
+        }
+        // 去除所有空白字符后计算长度
+        return text.replaceAll("\\s", "").length();
+    }
+
+    /**
+     * 更新字符统计显示
+     */
+    private void updateCharCount() {
+        int charCount = 0;
+        if (mWorkingNote.getCheckListMode() == TextNote.MODE_CHECK_LIST) {
+            // 列表模式：遍历所有列表项
+            for (int i = 0; i < mEditTextList.getChildCount(); i++) {
+                View view = mEditTextList.getChildAt(i);
+                NoteEditText edit = (NoteEditText) view.findViewById(R.id.et_edit_text);
+                if (!TextUtils.isEmpty(edit.getText())) {
+                    charCount += countValidCharacters(edit.getText().toString());
+                }
+            }
+        } else {
+            // 普通文本模式：直接计算编辑框内容
+            if (!TextUtils.isEmpty(mNoteEditor.getText())) {
+                charCount = countValidCharacters(mNoteEditor.getText().toString());
+            }
+        }
+        // 更新显示
+        if (mTvCharCount != null) {
+            mTvCharCount.setText(charCount + " 字符");
+        }
+    }
+
     /**
      * 打开模板选择页面
      * <p>

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

@@ -37,6 +37,7 @@ import android.view.MenuItem;
 import android.view.MenuItem.OnMenuItemClickListener;
 import android.view.MotionEvent;
 import android.widget.EditText;
+import android.text.TextWatcher;
 
 import net.micode.notes.R;
 
@@ -112,6 +113,11 @@ public class NoteEditText extends EditText {
          * 当文本变化时，隐藏或显示项目选项
          */
         void onTextChange(int index, boolean hasText);
+        
+        /**
+         * 当文本内容变化时，更新字符统计
+         */
+        void onContentChange();
     }
 
     /**
@@ -151,6 +157,8 @@ public class NoteEditText extends EditText {
      */
     public NoteEditText(Context context, AttributeSet attrs) {
         super(context, attrs, android.R.attr.editTextStyle);
+        mIndex = 0;
+        initTextWatcher();
     }
 
     /**
@@ -161,7 +169,30 @@ public class NoteEditText extends EditText {
      */
     public NoteEditText(Context context, AttributeSet attrs, int defStyle) {
         super(context, attrs, defStyle);
-        // TODO Auto-generated constructor stub
+        mIndex = 0;
+        initTextWatcher();
+    }
+
+    /**
+     * 初始化文本变化监听器
+     */
+    private void initTextWatcher() {
+        addTextChangedListener(new TextWatcher() {
+            @Override
+            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
+            }
+
+            @Override
+            public void onTextChanged(CharSequence s, int start, int before, int count) {
+            }
+
+            @Override
+            public void afterTextChanged(android.text.Editable s) {
+                if (mOnTextViewChangeListener != null) {
+                    mOnTextViewChangeListener.onContentChange();
+                }
+            }
+        });
     }
 
     /**
@@ -207,7 +238,9 @@ public class NoteEditText extends EditText {
     public boolean onKeyDown(int keyCode, KeyEvent event) {
         switch (keyCode) {
             case KeyEvent.KEYCODE_ENTER:
-                if (mOnTextViewChangeListener != null) {
+                // 只有在列表模式下（mIndex > 0）才阻止默认行为
+                // 普通文本模式下让系统默认处理回车键
+                if (mOnTextViewChangeListener != null && mIndex > 0) {
                     return false;
                 }
                 break;
@@ -244,10 +277,14 @@ public class NoteEditText extends EditText {
                 break;
             case KeyEvent.KEYCODE_ENTER:
                 if (mOnTextViewChangeListener != null) {
-                    int selectionStart = getSelectionStart();
-                    String text = getText().subSequence(selectionStart, length()).toString();
-                    setText(getText().subSequence(0, selectionStart));
-                    mOnTextViewChangeListener.onEditTextEnter(mIndex + 1, text);
+                    // 只有在列表模式下（mIndex > 0）才执行特殊处理
+                    // 普通文本模式下，让系统默认处理回车键
+                    if (mIndex > 0) {
+                        int selectionStart = getSelectionStart();
+                        String text = getText().subSequence(selectionStart, length()).toString();
+                        setText(getText().subSequence(0, selectionStart));
+                        mOnTextViewChangeListener.onEditTextEnter(mIndex + 1, text);
+                    }
                 } else {
                     Log.d(TAG, "OnTextViewChangeListener was not seted");
                 }

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

@@ -57,6 +57,7 @@ public class NoteItemData {
         NoteColumns.IS_LOCKED,
         NoteColumns.LOCK_PASSWORD,
         NoteColumns.LOCK_TYPE,
+        NoteColumns.LOCK_HINT,
         NoteColumns.DELETED_DATE,
     };
 
@@ -140,10 +141,15 @@ public class NoteItemData {
      */
     private static final int LOCK_TYPE_COLUMN             = 15;
     
+    /**
+     * 查询结果中密码提示列的索引
+     */
+    private static final int LOCK_HINT_COLUMN             = 16;
+    
     /**
      * 查询结果中删除日期列的索引
      */
-    private static final int DELETED_DATE_COLUMN          = 16;
+    private static final int DELETED_DATE_COLUMN          = 17;
 
     /**
      * 笔记ID
@@ -170,6 +176,11 @@ public class NoteItemData {
      */
     private int mLockType;
     
+    /**
+     * 密码提示
+     */
+    private String mLockHint;
+    
     /**
      * 提醒日期
      */
@@ -290,6 +301,7 @@ public class NoteItemData {
         mIsLocked = (cursor.getInt(IS_LOCKED_COLUMN) > 0) ? true : false;
         mLockPassword = cursor.getString(LOCK_PASSWORD_COLUMN);
         mLockType = cursor.getInt(LOCK_TYPE_COLUMN);
+        mLockHint = cursor.getString(LOCK_HINT_COLUMN);
         mDeletedDate = cursor.getLong(DELETED_DATE_COLUMN);
 
         mPhoneNumber = "";
@@ -565,6 +577,22 @@ public class NoteItemData {
         return mLockType;
     }
     
+    /**
+     * 获取密码提示
+     * @return 密码提示字符串
+     */
+    public String getLockHint() {
+        return mLockHint;
+    }
+    
+    /**
+     * 设置密码提示
+     * @param hint 密码提示字符串
+     */
+    public void setLockHint(String hint) {
+        mLockHint = hint;
+    }
+    
     /**
      * 设置锁定类型
      * @param type 锁定类型，0表示笔记，1表示文件夹

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

@@ -57,8 +57,10 @@ import android.widget.Button;
 import android.widget.EditText;
 import android.widget.ListView;
 import android.widget.PopupMenu;
+import android.widget.LinearLayout;
 import android.widget.TextView;
 import android.widget.Toast;
+import android.util.TypedValue;
 
 import net.micode.notes.R;
 import net.micode.notes.data.Notes;
@@ -124,19 +126,37 @@ public class NotesListActivity extends Activity implements OnClickListener, OnIt
      * </p>
      */
     private void showPasswordDialog() {
+        // 创建布局并添加输入框
+        LinearLayout layout = new LinearLayout(this);
+        layout.setOrientation(LinearLayout.VERTICAL);
+        layout.setPadding(60, 40, 60, 40);
+
+        // 创建布局参数，用于设置子视图间距
+        LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
+                LinearLayout.LayoutParams.MATCH_PARENT,
+                LinearLayout.LayoutParams.WRAP_CONTENT);
+        params.setMargins(0, 0, 0, 20); // 底部外边距作为间距
+
         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);
+        layout.addView(passwordEditText, params);
+
+        // 添加密码提示输入框
+        final EditText hintEditText = new EditText(this);
+        hintEditText.setHint(R.string.hint_enter_password_hint);
+        layout.addView(hintEditText);
 
         new AlertDialog.Builder(this)
                 .setTitle(R.string.dialog_enter_password)
-                .setView(passwordEditText)
+                .setView(layout)
                 .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
                     @Override
                     public void onClick(DialogInterface dialog, int which) {
                         String password = passwordEditText.getText().toString();
+                        String hint = hintEditText.getText().toString();
                         if (!TextUtils.isEmpty(password)) {
-                            toggleLockedStatus(password);
+                            toggleLockedStatus(password, hint);
                         }
                     }
                 })
@@ -150,8 +170,9 @@ public class NotesListActivity extends Activity implements OnClickListener, OnIt
      * 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
+     * @param hint 用于帮助记忆密码的提示
      */
-    private void toggleLockedStatus(final String password) {
+    private void toggleLockedStatus(final String password, final String hint) {
         final HashSet<Long> selectedIds = mNotesListAdapter.getSelectedItemIds();
         final int selectedCount = mNotesListAdapter.getSelectedCount();
 
@@ -159,45 +180,61 @@ public class NotesListActivity extends Activity implements OnClickListener, OnIt
             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
+                    // 查询当前便签的锁定状态和密码
                     Cursor cursor = mContentResolver.query(Notes.CONTENT_NOTE_URI,
-                            new String[]{NoteColumns.IS_LOCKED},
+                            new String[]{NoteColumns.IS_LOCKED, NoteColumns.LOCK_PASSWORD},
                             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();
+                        String encryptedPassword = cursor.getString(1);
+                        int newLocked = currentLocked;
+
+                        if (currentLocked == 1) {
+                            // 如果当前是锁定状态，需要验证密码才能解锁
+                            if (encryptedPassword != null && encryptedPassword.equals(encryptPassword(password))) {
+                                // 密码正确，解锁
+                                newLocked = 0;
+                                finalLockedStatus = newLocked;
                             }
                         } else {
-                            // 如果是解锁操作，清空密码
-                            values.put(NoteColumns.LOCK_PASSWORD, "");
+                            // 如果当前是未锁定状态，直接锁定
+                            newLocked = 1;
+                            finalLockedStatus = newLocked;
                         }
 
-                        mContentResolver.update(Notes.CONTENT_NOTE_URI,
-                                values,
-                                NoteColumns.ID + "=?",
-                                new String[]{String.valueOf(noteId)});
+                        if (newLocked != currentLocked) {
+                            ContentValues values = new ContentValues();
+                            values.put(NoteColumns.IS_LOCKED, newLocked);
+
+                            if (newLocked == 1) {
+                                // 如果是锁定操作，设置密码、密码提示和锁定类型
+                                values.put(NoteColumns.LOCK_PASSWORD, encryptPassword(password));
+                                values.put(NoteColumns.LOCK_HINT, hint);
+                                // 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，清空密码和密码提示
+                                values.put(NoteColumns.LOCK_PASSWORD, "");
+                                values.put(NoteColumns.LOCK_HINT, "");
+                            }
+
+                            mContentResolver.update(Notes.CONTENT_NOTE_URI,
+                                    values,
+                                    NoteColumns.ID + "=?",
+                                    new String[]{String.valueOf(noteId)});
+                        }
 
                         cursor.close();
                     }
@@ -207,11 +244,17 @@ public class NotesListActivity extends Activity implements OnClickListener, OnIt
 
             @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();
+                if (finalLockedStatus == -1) {
+                    // 密码错误，显示错误信息
+                    Toast.makeText(NotesListActivity.this, getString(R.string.error_wrong_password), Toast.LENGTH_SHORT).show();
+                } else {
+                    // 操作成功，显示结果
+                    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();
     }
@@ -1193,13 +1236,35 @@ public class NotesListActivity extends Activity implements OnClickListener, OnIt
     private void openNode(final NoteItemData data) {
         // 检查笔记是否被锁定
         if (data.isLocked()) {
+            // 创建布局并添加密码输入框
+            LinearLayout layout = new LinearLayout(this);
+            layout.setOrientation(LinearLayout.VERTICAL);
+            layout.setPadding(60, 40, 60, 40);
+
+            // 创建布局参数，用于设置子视图间距
+            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
+                    LinearLayout.LayoutParams.MATCH_PARENT,
+                    LinearLayout.LayoutParams.WRAP_CONTENT);
+            params.setMargins(0, 0, 0, 20); // 底部外边距作为间距
+
             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);
+            layout.addView(passwordEditText, params);
+
+            // 获取密码提示并显示
+            String lockHint = data.getLockHint();
+            if (!TextUtils.isEmpty(lockHint)) {
+                TextView hintTextView = new TextView(this);
+                hintTextView.setText(getString(R.string.password_hint_prefix) + lockHint);
+                hintTextView.setTextColor(getResources().getColor(R.color.secondary_text_dark));
+                hintTextView.setTextSize(TypedValue.COMPLEX_UNIT_SP, 14);
+                layout.addView(hintTextView);
+            }
 
             new AlertDialog.Builder(this)
                     .setTitle(R.string.dialog_enter_password)
-                    .setView(passwordEditText)
+                    .setView(layout)
                     .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
                         @Override
                         public void onClick(DialogInterface dialog, int which) {

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

@@ -99,20 +99,34 @@ public class NotesListItem extends LinearLayout {
             mTitle.setTextAppearance(context, R.style.TextAppearancePrimaryItem);
             mTitle.setText(context.getString(R.string.call_record_folder_name)
                     + context.getString(R.string.format_folder_files_count, data.getNotesCount()));
-            mAlert.setImageResource(R.drawable.call_record);
+            // 检查是否被锁定
+            if (data.isLocked()) {
+                mAlert.setImageResource(android.R.drawable.ic_lock_lock);
+            } else {
+                mAlert.setImageResource(R.drawable.call_record);
+            }
         } else if (data.getId() == Notes.ID_TRASH_FOLER) {
             mCallName.setVisibility(View.GONE);
             mAlert.setVisibility(View.VISIBLE);
             mTitle.setTextAppearance(context, R.style.TextAppearancePrimaryItem);
             mTitle.setText("回收站"
                     + context.getString(R.string.format_folder_files_count, data.getNotesCount()));
-            mAlert.setImageResource(R.drawable.delete);
+            // 检查是否被锁定
+            if (data.isLocked()) {
+                mAlert.setImageResource(android.R.drawable.ic_lock_lock);
+            } else {
+                mAlert.setImageResource(R.drawable.delete);
+            }
         } else if (data.getParentId() == Notes.ID_CALL_RECORD_FOLDER) {
             mCallName.setVisibility(View.VISIBLE);
             mCallName.setText(data.getCallName());
             mTitle.setTextAppearance(context,R.style.TextAppearanceSecondaryItem);
             mTitle.setText(Html.fromHtml(DataUtils.getFormattedSnippet(data.getSnippet())));
-            if (data.hasAlert()) {
+            // 检查是否被锁定
+            if (data.isLocked()) {
+                mAlert.setImageResource(android.R.drawable.ic_lock_lock);
+                mAlert.setVisibility(View.VISIBLE);
+            } else if (data.hasAlert()) {
                 mAlert.setImageResource(R.drawable.clock);
                 mAlert.setVisibility(View.VISIBLE);
             } else {
@@ -126,10 +140,20 @@ public class NotesListItem extends LinearLayout {
                 mTitle.setText(data.getSnippet()
                         + context.getString(R.string.format_folder_files_count, 
                                 data.getNotesCount()));
-                mAlert.setVisibility(View.GONE);
+                // 检查文件夹是否被锁定
+                if (data.isLocked()) {
+                    mAlert.setImageResource(android.R.drawable.ic_lock_lock);
+                    mAlert.setVisibility(View.VISIBLE);
+                } else {
+                    mAlert.setVisibility(View.GONE);
+                }
             } else {
                 mTitle.setText(Html.fromHtml(DataUtils.getFormattedSnippet(data.getSnippet())));
-                if (data.hasAlert()) {
+                // 检查笔记是否被锁定
+                if (data.isLocked()) {
+                    mAlert.setImageResource(android.R.drawable.ic_lock_lock);
+                    mAlert.setVisibility(View.VISIBLE);
+                } else if (data.hasAlert()) {
                     mAlert.setImageResource(R.drawable.clock);
                     mAlert.setVisibility(View.VISIBLE);
                 } else {

src/main/res/layout/note_edit.xml

@@ -181,6 +181,17 @@
                 </LinearLayout>
             </ScrollView>
 
+            <TextView
+                android:id="@+id/tv_char_count"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_gravity="left|bottom"
+                android:layout_marginLeft="16dp"
+                android:layout_marginBottom="8dp"
+                android:textSize="12sp"
+                android:textColor="@color/secondary_text_dark"
+                android:text="0 字符" />
+
             <ImageView
                 android:layout_width="fill_parent"
                 android:layout_height="7dip"

src/main/res/menu/note_edit.xml

@@ -57,6 +57,10 @@
     <item
         android:id="@+id/menu_unlock"
         android:title="@string/menu_unlock" />
+        
+    <item
+        android:id="@+id/menu_change_password"
+        android:title="@string/menu_change_password" />
 
     <item
         android:id="@+id/menu_note_template"

src/main/res/values/strings.xml

@@ -52,11 +52,17 @@
     <string name="menu_unpin">Unpin</string>
     <string name="menu_lock">Lock</string>
     <string name="menu_unlock">Unlock</string>
+    <string name="menu_change_password">Change Password</string>
     <string name="dialog_enter_password">Enter Password</string>
+    <string name="dialog_enter_old_password">Enter Old Password</string>
+    <string name="dialog_enter_new_password">Enter New Password</string>
     <string name="hint_enter_password">Please enter password</string>
+    <string name="hint_enter_password_hint">Please enter password hint</string>
+    <string name="password_hint_prefix">Hint: </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="message_password_changed">Password changed 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>