diff --git a/src/Notes-master/src/net/micode/notes/data/Contact.java b/src/Notes-master/src/net/micode/notes/data/Contact.java
index d97ac5d..0a9d168 100644
--- a/src/Notes-master/src/net/micode/notes/data/Contact.java
+++ b/src/Notes-master/src/net/micode/notes/data/Contact.java
@@ -13,38 +13,41 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
+ 
 package net.micode.notes.data;
-
+ 
 import android.content.Context;
 import android.database.Cursor;
 import android.provider.ContactsContract.CommonDataKinds.Phone;
 import android.provider.ContactsContract.Data;
 import android.telephony.PhoneNumberUtils;
 import android.util.Log;
-
+ 
 import java.util.HashMap;
-
+ 
+// 联系人类，用于从设备中获取联系人信息
 public class Contact {
-    private static HashMap<String, String> sContactCache;
-    private static final String TAG = "Contact";
-
+    private static HashMap<String, String> sContactCache; // 缓存联系人信息，以提高查询效率
+    private static final String TAG = "Contact"; // 日志标签
+ 
+    // 查询联系人时使用的 SQL 选择条件，确保电话号码匹配且 MIME 类型为电话号码类型
     private static final String CALLER_ID_SELECTION = "PHONE_NUMBERS_EQUAL(" + Phone.NUMBER
     + ",?) AND " + Data.MIMETYPE + "='" + Phone.CONTENT_ITEM_TYPE + "'"
     + " AND " + Data.RAW_CONTACT_ID + " IN "
             + "(SELECT raw_contact_id "
             + " FROM phone_lookup"
             + " WHERE min_match = '+')";
-
+ 
+    // 根据电话号码获取联系人姓名，首先检查缓存，然后查询数据库
     public static String getContact(Context context, String phoneNumber) {
         if(sContactCache == null) {
             sContactCache = new HashMap<String, String>();
         }
-
+ 
         if(sContactCache.containsKey(phoneNumber)) {
             return sContactCache.get(phoneNumber);
         }
-
+ 
         String selection = CALLER_ID_SELECTION.replace("+",
                 PhoneNumberUtils.toCallerIDMinMatch(phoneNumber));
         Cursor cursor = context.getContentResolver().query(
@@ -53,7 +56,7 @@ public class Contact {
                 selection,
                 new String[] { phoneNumber },
                 null);
-
+ 
         if (cursor != null && cursor.moveToFirst()) {
             try {
                 String name = cursor.getString(0);
@@ -70,4 +73,4 @@ public class Contact {
             return null;
         }
     }
-}
+}
\ No newline at end of file
diff --git a/src/Notes-master/src/net/micode/notes/data/Notes.java b/src/Notes-master/src/net/micode/notes/data/Notes.java
index f240604..539c53b 100644
--- a/src/Notes-master/src/net/micode/notes/data/Notes.java
+++ b/src/Notes-master/src/net/micode/notes/data/Notes.java
@@ -13,17 +13,19 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
+ 
 package net.micode.notes.data;
-
+ 
 import android.net.Uri;
+ 
+// Notes 类定义了笔记应用中使用的常量和接口
 public class Notes {
     public static final String AUTHORITY = "micode_notes";
     public static final String TAG = "Notes";
     public static final int TYPE_NOTE     = 0;
     public static final int TYPE_FOLDER   = 1;
     public static final int TYPE_SYSTEM   = 2;
-
+ 
     /**
      * Following IDs are system folders' identifiers
      * {@link Notes#ID_ROOT_FOLDER } is default folder
@@ -34,205 +36,206 @@ public class Notes {
     public static final int ID_TEMPARAY_FOLDER = -1;
     public static final int ID_CALL_RECORD_FOLDER = -2;
     public static final int ID_TRASH_FOLER = -3;
-
+ 
     public static final String INTENT_EXTRA_ALERT_DATE = "net.micode.notes.alert_date";
     public static final String INTENT_EXTRA_BACKGROUND_ID = "net.micode.notes.background_color_id";
     public static final String INTENT_EXTRA_WIDGET_ID = "net.micode.notes.widget_id";
     public static final String INTENT_EXTRA_WIDGET_TYPE = "net.micode.notes.widget_type";
     public static final String INTENT_EXTRA_FOLDER_ID = "net.micode.notes.folder_id";
     public static final String INTENT_EXTRA_CALL_DATE = "net.micode.notes.call_date";
-
+ 
     public static final int TYPE_WIDGET_INVALIDE      = -1;
     public static final int TYPE_WIDGET_2X            = 0;
     public static final int TYPE_WIDGET_4X            = 1;
-
+ 
+    // DataConstants 类定义了不同类型的笔记数据常量
     public static class DataConstants {
         public static final String NOTE = TextNote.CONTENT_ITEM_TYPE;
         public static final String CALL_NOTE = CallNote.CONTENT_ITEM_TYPE;
     }
-
+ 
     /**
      * Uri to query all notes and folders
      */
     public static final Uri CONTENT_NOTE_URI = Uri.parse("content://" + AUTHORITY + "/note");
-
+ 
     /**
      * Uri to query data
      */
     public static final Uri CONTENT_DATA_URI = Uri.parse("content://" + AUTHORITY + "/data");
-
+ 
+    // NoteColumns 接口定义了笔记和文件夹的公共列名
     public interface NoteColumns {
         /**
          * The unique ID for a row
          * <P> Type: INTEGER (long) </P>
          */
         public static final String ID = "_id";
-
+ 
         /**
          * The parent's id for note or folder
          * <P> Type: INTEGER (long) </P>
          */
         public static final String PARENT_ID = "parent_id";
-
+ 
         /**
          * Created data for note or folder
          * <P> Type: INTEGER (long) </P>
          */
         public static final String CREATED_DATE = "created_date";
-
+ 
         /**
          * Latest modified date
          * <P> Type: INTEGER (long) </P>
          */
         public static final String MODIFIED_DATE = "modified_date";
-
-
+ 
         /**
          * Alert date
          * <P> Type: INTEGER (long) </P>
          */
         public static final String ALERTED_DATE = "alert_date";
-
+ 
         /**
          * Folder's name or text content of note
          * <P> Type: TEXT </P>
          */
         public static final String SNIPPET = "snippet";
-
+ 
         /**
          * Note's widget id
          * <P> Type: INTEGER (long) </P>
          */
         public static final String WIDGET_ID = "widget_id";
-
+ 
         /**
          * Note's widget type
          * <P> Type: INTEGER (long) </P>
          */
         public static final String WIDGET_TYPE = "widget_type";
-
+ 
         /**
          * Note's background color's id
          * <P> Type: INTEGER (long) </P>
          */
         public static final String BG_COLOR_ID = "bg_color_id";
-
+ 
         /**
          * For text note, it doesn't has attachment, for multi-media
          * note, it has at least one attachment
          * <P> Type: INTEGER </P>
          */
         public static final String HAS_ATTACHMENT = "has_attachment";
-
+ 
         /**
          * Folder's count of notes
          * <P> Type: INTEGER (long) </P>
          */
         public static final String NOTES_COUNT = "notes_count";
-
+ 
         /**
          * The file type: folder or note
          * <P> Type: INTEGER </P>
          */
         public static final String TYPE = "type";
-
+ 
         /**
          * The last sync id
          * <P> Type: INTEGER (long) </P>
          */
         public static final String SYNC_ID = "sync_id";
-
+ 
         /**
          * Sign to indicate local modified or not
          * <P> Type: INTEGER </P>
          */
         public static final String LOCAL_MODIFIED = "local_modified";
-
+ 
         /**
          * Original parent id before moving into temporary folder
          * <P> Type : INTEGER </P>
          */
         public static final String ORIGIN_PARENT_ID = "origin_parent_id";
-
+ 
         /**
          * The gtask id
          * <P> Type : TEXT </P>
          */
         public static final String GTASK_ID = "gtask_id";
-
+ 
         /**
          * The version code
          * <P> Type : INTEGER (long) </P>
          */
         public static final String VERSION = "version";
     }
-
+ 
+    // DataColumns 接口定义了笔记数据的公共列名
     public interface DataColumns {
         /**
          * The unique ID for a row
          * <P> Type: INTEGER (long) </P>
          */
         public static final String ID = "_id";
-
+ 
         /**
          * The MIME type of the item represented by this row.
          * <P> Type: Text </P>
          */
         public static final String MIME_TYPE = "mime_type";
-
+ 
         /**
          * The reference id to note that this data belongs to
          * <P> Type: INTEGER (long) </P>
          */
         public static final String NOTE_ID = "note_id";
-
+ 
         /**
          * Created data for note or folder
          * <P> Type: INTEGER (long) </P>
          */
         public static final String CREATED_DATE = "created_date";
-
+ 
         /**
          * Latest modified date
          * <P> Type: INTEGER (long) </P>
          */
         public static final String MODIFIED_DATE = "modified_date";
-
+ 
         /**
          * Data's content
          * <P> Type: TEXT </P>
          */
         public static final String CONTENT = "content";
-
-
+ 
         /**
          * Generic data column, the meaning is {@link #MIMETYPE} specific, used for
          * integer data type
          * <P> Type: INTEGER </P>
          */
         public static final String DATA1 = "data1";
-
+ 
         /**
          * Generic data column, the meaning is {@link #MIMETYPE} specific, used for
          * integer data type
          * <P> Type: INTEGER </P>
          */
         public static final String DATA2 = "data2";
-
+ 
         /**
          * Generic data column, the meaning is {@link #MIMETYPE} specific, used for
          * TEXT data type
          * <P> Type: TEXT </P>
          */
         public static final String DATA3 = "data3";
-
+ 
         /**
          * Generic data column, the meaning is {@link #MIMETYPE} specific, used for
          * TEXT data type
          * <P> Type: TEXT </P>
          */
         public static final String DATA4 = "data4";
-
+ 
         /**
          * Generic data column, the meaning is {@link #MIMETYPE} specific, used for
          * TEXT data type
@@ -240,40 +243,42 @@ public class Notes {
          */
         public static final String DATA5 = "data5";
     }
-
+ 
+    // TextNote 类定义了文本笔记的相关信息和 URI
     public static final class TextNote implements DataColumns {
         /**
          * Mode to indicate the text in check list mode or not
          * <P> Type: Integer 1:check list mode 0: normal mode </P>
          */
         public static final String MODE = DATA1;
-
+ 
         public static final int MODE_CHECK_LIST = 1;
-
+ 
         public static final String CONTENT_TYPE = "vnd.android.cursor.dir/text_note";
-
+ 
         public static final String CONTENT_ITEM_TYPE = "vnd.android.cursor.item/text_note";
-
+ 
         public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY + "/text_note");
     }
-
+ 
+    // CallNote 类定义了通话记录相关的信息和 URI
     public static final class CallNote implements DataColumns {
         /**
          * Call date for this record
          * <P> Type: INTEGER (long) </P>
          */
         public static final String CALL_DATE = DATA1;
-
+ 
         /**
          * Phone number for this record
          * <P> Type: TEXT </P>
          */
         public static final String PHONE_NUMBER = DATA3;
-
+ 
         public static final String CONTENT_TYPE = "vnd.android.cursor.dir/call_note";
-
+ 
         public static final String CONTENT_ITEM_TYPE = "vnd.android.cursor.item/call_note";
-
+ 
         public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY + "/call_note");
     }
-}
+}
\ No newline at end of file
diff --git a/src/Notes-master/src/net/micode/notes/data/NotesDatabaseHelper.java b/src/Notes-master/src/net/micode/notes/data/NotesDatabaseHelper.java
index ffe5d57..eb9d445 100644
--- a/src/Notes-master/src/net/micode/notes/data/NotesDatabaseHelper.java
+++ b/src/Notes-master/src/net/micode/notes/data/NotesDatabaseHelper.java
@@ -1,47 +1,31 @@
-/*
- * 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.data;
-
+ 
 import android.content.ContentValues;
 import android.content.Context;
 import android.database.sqlite.SQLiteDatabase;
 import android.database.sqlite.SQLiteOpenHelper;
 import android.util.Log;
-
+ 
 import net.micode.notes.data.Notes.DataColumns;
 import net.micode.notes.data.Notes.DataConstants;
 import net.micode.notes.data.Notes.NoteColumns;
-
-
+ 
+// NotesDatabaseHelper 类用于管理笔记应用的 SQLite 数据库
 public class NotesDatabaseHelper extends SQLiteOpenHelper {
     private static final String DB_NAME = "note.db";
-
+ 
     private static final int DB_VERSION = 4;
-
+ 
     public interface TABLE {
         public static final String NOTE = "note";
-
+ 
         public static final String DATA = "data";
     }
-
+ 
     private static final String TAG = "NotesDatabaseHelper";
-
+ 
     private static NotesDatabaseHelper mInstance;
-
+ 
     private static final String CREATE_NOTE_TABLE_SQL =
         "CREATE TABLE " + TABLE.NOTE + "(" +
             NoteColumns.ID + " INTEGER PRIMARY KEY," +
@@ -62,7 +46,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
             NoteColumns.GTASK_ID + " TEXT NOT NULL DEFAULT ''," +
             NoteColumns.VERSION + " INTEGER NOT NULL DEFAULT 0" +
         ")";
-
+ 
     private static final String CREATE_DATA_TABLE_SQL =
         "CREATE TABLE " + TABLE.DATA + "(" +
             DataColumns.ID + " INTEGER PRIMARY KEY," +
@@ -77,11 +61,11 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
             DataColumns.DATA4 + " TEXT NOT NULL DEFAULT ''," +
             DataColumns.DATA5 + " TEXT NOT NULL DEFAULT ''" +
         ")";
-
+ 
     private static final String CREATE_DATA_NOTE_ID_INDEX_SQL =
         "CREATE INDEX IF NOT EXISTS note_id_index ON " +
         TABLE.DATA + "(" + DataColumns.NOTE_ID + ");";
-
+ 
     /**
      * Increase folder's note count when move note to the folder
      */
@@ -93,7 +77,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         "   SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + " + 1" +
         "  WHERE " + NoteColumns.ID + "=new." + NoteColumns.PARENT_ID + ";" +
         " END";
-
+ 
     /**
      * Decrease folder's note count when move note from folder
      */
@@ -106,7 +90,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         "  WHERE " + NoteColumns.ID + "=old." + NoteColumns.PARENT_ID +
         "  AND " + NoteColumns.NOTES_COUNT + ">0" + ";" +
         " END";
-
+ 
     /**
      * Increase folder's note count when insert new note to the folder
      */
@@ -118,7 +102,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         "   SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + " + 1" +
         "  WHERE " + NoteColumns.ID + "=new." + NoteColumns.PARENT_ID + ";" +
         " END";
-
+ 
     /**
      * Decrease folder's note count when delete note from the folder
      */
@@ -131,7 +115,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         "  WHERE " + NoteColumns.ID + "=old." + NoteColumns.PARENT_ID +
         "  AND " + NoteColumns.NOTES_COUNT + ">0;" +
         " END";
-
+ 
     /**
      * Update note's content when insert data with type {@link DataConstants#NOTE}
      */
@@ -144,7 +128,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         "   SET " + NoteColumns.SNIPPET + "=new." + DataColumns.CONTENT +
         "  WHERE " + NoteColumns.ID + "=new." + DataColumns.NOTE_ID + ";" +
         " END";
-
+ 
     /**
      * Update note's content when data with {@link DataConstants#NOTE} type has changed
      */
@@ -157,7 +141,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         "   SET " + NoteColumns.SNIPPET + "=new." + DataColumns.CONTENT +
         "  WHERE " + NoteColumns.ID + "=new." + DataColumns.NOTE_ID + ";" +
         " END";
-
+ 
     /**
      * Update note's content when data with {@link DataConstants#NOTE} type has deleted
      */
@@ -170,7 +154,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         "   SET " + NoteColumns.SNIPPET + "=''" +
         "  WHERE " + NoteColumns.ID + "=old." + DataColumns.NOTE_ID + ";" +
         " END";
-
+ 
     /**
      * Delete datas belong to note which has been deleted
      */
@@ -181,7 +165,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         "  DELETE FROM " + TABLE.DATA +
         "   WHERE " + DataColumns.NOTE_ID + "=old." + NoteColumns.ID + ";" +
         " END";
-
+ 
     /**
      * Delete notes belong to folder which has been deleted
      */
@@ -192,7 +176,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         "  DELETE FROM " + TABLE.NOTE +
         "   WHERE " + NoteColumns.PARENT_ID + "=old." + NoteColumns.ID + ";" +
         " END";
-
+ 
     /**
      * Move notes belong to folder which has been moved to trash folder
      */
@@ -205,18 +189,21 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         "   SET " + NoteColumns.PARENT_ID + "=" + Notes.ID_TRASH_FOLER +
         "  WHERE " + NoteColumns.PARENT_ID + "=old." + NoteColumns.ID + ";" +
         " END";
-
+ 
+    // 构造函数，初始化数据库名称和版本
     public NotesDatabaseHelper(Context context) {
         super(context, DB_NAME, null, DB_VERSION);
     }
-
+ 
+    // 创建笔记表及其触发器，并插入系统文件夹
     public void createNoteTable(SQLiteDatabase db) {
         db.execSQL(CREATE_NOTE_TABLE_SQL);
         reCreateNoteTableTriggers(db);
         createSystemFolder(db);
         Log.d(TAG, "note table has been created");
     }
-
+ 
+    // 重新创建笔记表的触发器
     private void reCreateNoteTableTriggers(SQLiteDatabase db) {
         db.execSQL("DROP TRIGGER IF EXISTS increase_folder_count_on_update");
         db.execSQL("DROP TRIGGER IF EXISTS decrease_folder_count_on_update");
@@ -225,7 +212,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         db.execSQL("DROP TRIGGER IF EXISTS increase_folder_count_on_insert");
         db.execSQL("DROP TRIGGER IF EXISTS folder_delete_notes_on_delete");
         db.execSQL("DROP TRIGGER IF EXISTS folder_move_notes_on_trash");
-
+ 
         db.execSQL(NOTE_INCREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER);
         db.execSQL(NOTE_DECREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER);
         db.execSQL(NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER);
@@ -234,17 +221,18 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         db.execSQL(FOLDER_DELETE_NOTES_ON_DELETE_TRIGGER);
         db.execSQL(FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER);
     }
-
+ 
+    // 创建系统文件夹
     private void createSystemFolder(SQLiteDatabase db) {
         ContentValues values = new ContentValues();
-
+ 
         /**
          * call record foler for call notes
          */
         values.put(NoteColumns.ID, Notes.ID_CALL_RECORD_FOLDER);
         values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
         db.insert(TABLE.NOTE, null, values);
-
+ 
         /**
          * root folder which is default folder
          */
@@ -252,7 +240,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         values.put(NoteColumns.ID, Notes.ID_ROOT_FOLDER);
         values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
         db.insert(TABLE.NOTE, null, values);
-
+ 
         /**
          * temporary folder which is used for moving note
          */
@@ -260,7 +248,7 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         values.put(NoteColumns.ID, Notes.ID_TEMPARAY_FOLDER);
         values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
         db.insert(TABLE.NOTE, null, values);
-
+ 
         /**
          * create trash folder
          */
@@ -269,77 +257,84 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
         db.insert(TABLE.NOTE, null, values);
     }
-
+ 
+    // 创建数据表及其触发器，并创建索引
     public void createDataTable(SQLiteDatabase db) {
         db.execSQL(CREATE_DATA_TABLE_SQL);
         reCreateDataTableTriggers(db);
         db.execSQL(CREATE_DATA_NOTE_ID_INDEX_SQL);
         Log.d(TAG, "data table has been created");
     }
-
+ 
+    // 重新创建数据表的触发器
     private void reCreateDataTableTriggers(SQLiteDatabase db) {
         db.execSQL("DROP TRIGGER IF EXISTS update_note_content_on_insert");
         db.execSQL("DROP TRIGGER IF EXISTS update_note_content_on_update");
         db.execSQL("DROP TRIGGER IF EXISTS update_note_content_on_delete");
-
+ 
         db.execSQL(DATA_UPDATE_NOTE_CONTENT_ON_INSERT_TRIGGER);
         db.execSQL(DATA_UPDATE_NOTE_CONTENT_ON_UPDATE_TRIGGER);
         db.execSQL(DATA_UPDATE_NOTE_CONTENT_ON_DELETE_TRIGGER);
     }
-
+ 
+    // 获取 NotesDatabaseHelper 的单例实例
     static synchronized NotesDatabaseHelper getInstance(Context context) {
         if (mInstance == null) {
             mInstance = new NotesDatabaseHelper(context);
         }
         return mInstance;
     }
-
+ 
+    // 创建数据库时调用，初始化数据库结构
     @Override
     public void onCreate(SQLiteDatabase db) {
         createNoteTable(db);
         createDataTable(db);
     }
-
+ 
+    // 数据库版本升级时调用，处理数据库结构的变更
     @Override
     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
         boolean reCreateTriggers = false;
         boolean skipV2 = false;
-
+ 
         if (oldVersion == 1) {
             upgradeToV2(db);
             skipV2 = true; // this upgrade including the upgrade from v2 to v3
             oldVersion++;
         }
-
+ 
         if (oldVersion == 2 && !skipV2) {
             upgradeToV3(db);
             reCreateTriggers = true;
             oldVersion++;
         }
-
+ 
         if (oldVersion == 3) {
             upgradeToV4(db);
             oldVersion++;
         }
-
+ 
         if (reCreateTriggers) {
             reCreateNoteTableTriggers(db);
             reCreateDataTableTriggers(db);
         }
-
+ 
         if (oldVersion != newVersion) {
             throw new IllegalStateException("Upgrade notes database to version " + newVersion
                     + "fails");
         }
     }
-
+ 
+    // 从版本 1 升级到版本 2，重新创建表结构
     private void upgradeToV2(SQLiteDatabase db) {
         db.execSQL("DROP TABLE IF EXISTS " + TABLE.NOTE);
         db.execSQL("DROP TABLE IF EXISTS " + TABLE.DATA);
         createNoteTable(db);
         createDataTable(db);
     }
-
+ 
+    // 从版本 2 升级到版本 3，添加系统回收站文件夹
     private void upgradeToV3(SQLiteDatabase db) {
         // drop unused triggers
         db.execSQL("DROP TRIGGER IF EXISTS update_note_modified_date_on_insert");
@@ -354,9 +349,10 @@ public class NotesDatabaseHelper extends SQLiteOpenHelper {
         values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
         db.insert(TABLE.NOTE, null, values);
     }
-
+ 
+    // 从版本 3 升级到版本 4，添加版本控制字段
     private void upgradeToV4(SQLiteDatabase db) {
         db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.VERSION
                 + " INTEGER NOT NULL DEFAULT 0");
     }
-}
+}
\ No newline at end of file
diff --git a/src/Notes-master/src/net/micode/notes/data/NotesProvider.java b/src/Notes-master/src/net/micode/notes/data/NotesProvider.java
index edb0a60..fb30add 100644
--- a/src/Notes-master/src/net/micode/notes/data/NotesProvider.java
+++ b/src/Notes-master/src/net/micode/notes/data/NotesProvider.java
@@ -13,10 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
+ 
 package net.micode.notes.data;
-
-
+ 
 import android.app.SearchManager;
 import android.content.ContentProvider;
 import android.content.ContentUris;
@@ -28,28 +27,28 @@ import android.database.sqlite.SQLiteDatabase;
 import android.net.Uri;
 import android.text.TextUtils;
 import android.util.Log;
-
+ 
 import net.micode.notes.R;
 import net.micode.notes.data.Notes.DataColumns;
 import net.micode.notes.data.Notes.NoteColumns;
 import net.micode.notes.data.NotesDatabaseHelper.TABLE;
-
-
+ 
+// NotesProvider 类继承自 ContentProvider，负责处理与笔记数据相关的数据库操作
 public class NotesProvider extends ContentProvider {
     private static final UriMatcher mMatcher;
-
+ 
     private NotesDatabaseHelper mHelper;
-
+ 
     private static final String TAG = "NotesProvider";
-
+ 
     private static final int URI_NOTE            = 1;
     private static final int URI_NOTE_ITEM       = 2;
     private static final int URI_DATA            = 3;
     private static final int URI_DATA_ITEM       = 4;
-
+ 
     private static final int URI_SEARCH          = 5;
     private static final int URI_SEARCH_SUGGEST  = 6;
-
+ 
     static {
         mMatcher = new UriMatcher(UriMatcher.NO_MATCH);
         mMatcher.addURI(Notes.AUTHORITY, "note", URI_NOTE);
@@ -60,7 +59,7 @@ public class NotesProvider extends ContentProvider {
         mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY, URI_SEARCH_SUGGEST);
         mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY + "/*", URI_SEARCH_SUGGEST);
     }
-
+ 
     /**
      * x'0A' represents the '\n' character in sqlite. For title and content in the search result,
      * we will trim '\n' and white space in order to show more information.
@@ -72,19 +71,21 @@ public class NotesProvider extends ContentProvider {
         + R.drawable.search_result + " AS " + SearchManager.SUGGEST_COLUMN_ICON_1 + ","
         + "'" + Intent.ACTION_VIEW + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_ACTION + ","
         + "'" + Notes.TextNote.CONTENT_TYPE + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_DATA;
-
+ 
     private static String NOTES_SNIPPET_SEARCH_QUERY = "SELECT " + NOTES_SEARCH_PROJECTION
         + " FROM " + TABLE.NOTE
         + " WHERE " + NoteColumns.SNIPPET + " LIKE ?"
         + " AND " + NoteColumns.PARENT_ID + "<>" + Notes.ID_TRASH_FOLER
         + " AND " + NoteColumns.TYPE + "=" + Notes.TYPE_NOTE;
-
+ 
+    // 初始化 ContentProvider，获取数据库帮助类实例
     @Override
     public boolean onCreate() {
         mHelper = NotesDatabaseHelper.getInstance(getContext());
         return true;
     }
-
+ 
+    // 根据 URI 查询数据，返回 Cursor 对象
     @Override
     public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
             String sortOrder) {
@@ -116,7 +117,7 @@ public class NotesProvider extends ContentProvider {
                     throw new IllegalArgumentException(
                             "do not specify sortOrder, selection, selectionArgs, or projection" + "with this query");
                 }
-
+ 
                 String searchString = null;
                 if (mMatcher.match(uri) == URI_SEARCH_SUGGEST) {
                     if (uri.getPathSegments().size() > 1) {
@@ -125,11 +126,11 @@ public class NotesProvider extends ContentProvider {
                 } else {
                     searchString = uri.getQueryParameter("pattern");
                 }
-
+ 
                 if (TextUtils.isEmpty(searchString)) {
                     return null;
                 }
-
+ 
                 try {
                     searchString = String.format("%%%s%%", searchString);
                     c = db.rawQuery(NOTES_SNIPPET_SEARCH_QUERY,
@@ -146,7 +147,8 @@ public class NotesProvider extends ContentProvider {
         }
         return c;
     }
-
+ 
+    // 插入新的笔记或笔记数据到数据库中
     @Override
     public Uri insert(Uri uri, ContentValues values) {
         SQLiteDatabase db = mHelper.getWritableDatabase();
@@ -171,16 +173,17 @@ public class NotesProvider extends ContentProvider {
             getContext().getContentResolver().notifyChange(
                     ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null);
         }
-
+ 
         // Notify the data uri
         if (dataId > 0) {
             getContext().getContentResolver().notifyChange(
                     ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId), null);
         }
-
+ 
         return ContentUris.withAppendedId(uri, insertedId);
     }
-
+ 
+    // 根据 URI 删除笔记或笔记数据
     @Override
     public int delete(Uri uri, String selection, String[] selectionArgs) {
         int count = 0;
@@ -226,7 +229,8 @@ public class NotesProvider extends ContentProvider {
         }
         return count;
     }
-
+ 
+    // 根据 URI 更新笔记或笔记数据
     @Override
     public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
         int count = 0;
@@ -257,7 +261,7 @@ public class NotesProvider extends ContentProvider {
             default:
                 throw new IllegalArgumentException("Unknown URI " + uri);
         }
-
+ 
         if (count > 0) {
             if (updateData) {
                 getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
@@ -266,11 +270,13 @@ public class NotesProvider extends ContentProvider {
         }
         return count;
     }
-
+ 
+    // 处理查询条件字符串
     private String parseSelection(String selection) {
         return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : "");
     }
-
+ 
+    // 增加笔记的版本号
     private void increaseNoteVersion(long id, String selection, String[] selectionArgs) {
         StringBuilder sql = new StringBuilder(120);
         sql.append("UPDATE ");
@@ -278,7 +284,7 @@ public class NotesProvider extends ContentProvider {
         sql.append(" SET ");
         sql.append(NoteColumns.VERSION);
         sql.append("=" + NoteColumns.VERSION + "+1 ");
-
+ 
         if (id > 0 || !TextUtils.isEmpty(selection)) {
             sql.append(" WHERE ");
         }
@@ -292,14 +298,15 @@ public class NotesProvider extends ContentProvider {
             }
             sql.append(selectString);
         }
-
+ 
         mHelper.getWritableDatabase().execSQL(sql.toString());
     }
-
+ 
+    // 返回与给定 URI 对应的 MIME 类型
     @Override
     public String getType(Uri uri) {
         // TODO Auto-generated method stub
         return null;
     }
-
-}
+ 
+}
\ No newline at end of file