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diff --git a/src/Contact.java b/src/Contact.java
new file mode 100644
index 0000000..a1c23bb
--- /dev/null
+++ b/src/Contact.java
@@ -0,0 +1,81 @@
+/*
+ * 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; // 包声明
+
+import android.content.Context; // 导入上下文
+import android.database.Cursor; // 导入游标
+import android.provider.ContactsContract.CommonDataKinds.Phone; // 导入电话数据类
+import android.provider.ContactsContract.Data; // 导入数据类
+import android.telephony.PhoneNumberUtils; // 导入电话号码工具
+import android.util.Log; // 导入日志
+
+import java.util.HashMap; // 导入哈希表
+
+// 联系人类
+public class Contact {
+    private static HashMap<String, String> sContactCache; // 联系人缓存
+    private static final String TAG = "Contact"; // 日志标签
+
+    // 呼叫者ID选择条件
+    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 = '+')";
+
+    // 获取联系人名称
+    public static String getContact(Context context, String phoneNumber) {
+        // 初始化联系人缓存
+        if(sContactCache == null) {
+            sContactCache = new HashMap<String, String>(); // 创建新缓存
+        }
+
+        // 如果缓存中已有联系人，直接返回
+        if(sContactCache.containsKey(phoneNumber)) {
+            return sContactCache.get(phoneNumber); // 从缓存中获取联系人
+        }
+
+        // 替换选择条件中的“+”符号
+        String selection = CALLER_ID_SELECTION.replace("+",
+                PhoneNumberUtils.toCallerIDMinMatch(phoneNumber)); // 更新选择条件
+        // 查询联系人数据
+        Cursor cursor = context.getContentResolver().query(
+                Data.CONTENT_URI, // 内容URI
+                new String [] { Phone.DISPLAY_NAME }, // 查询的列
+                selection, // 选择条件
+                new String[] { phoneNumber }, // 选择参数
+                null); // 排序
+
+        // 处理查询结果
+        if (cursor != null && cursor.moveToFirst()) {
+            try {
+                String name = cursor.getString(0); // 获取联系人名称
+                sContactCache.put(phoneNumber, name); // 将名称存入缓存
+                return name; // 返回联系人名称
+            } catch (IndexOutOfBoundsException e) {
+                Log.e(TAG, " Cursor get string error " + e.toString()); // 处理索引错误
+                return null; // 返回null
+            } finally {
+                cursor.close(); // 关闭游标
+            }
+        } else {
+            Log.d(TAG, "No contact matched with number:" + phoneNumber); // 无匹配联系人
+            return null; // 返回null
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/Notes.java b/src/Notes.java
new file mode 100644
index 0000000..c112c04
--- /dev/null
+++ b/src/Notes.java
@@ -0,0 +1,285 @@
+/*
+ * 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; // 包声明
+
+import android.net.Uri; // 导入URI类
+
+// 笔记类
+public class Notes {
+    public static final String AUTHORITY = "micode_notes"; // 权限标识
+    public static final String TAG = "Notes"; // 日志标签
+    public static final int TYPE_NOTE = 0; // 笔记类型
+    public static final int TYPE_FOLDER = 1; // 文件夹类型
+    public static final int TYPE_SYSTEM = 2; // 系统类型
+
+    /**
+     * 以下ID为系统文件夹的标识符
+     * {@link Notes#ID_ROOT_FOLDER} 是默认文件夹
+     * {@link Notes#ID_TEMPARAY_FOLDER} 是用于不属于任何文件夹的笔记
+     * {@link Notes#ID_CALL_RECORD_FOLDER} 用于存储通话记录
+     */
+    public static final int ID_ROOT_FOLDER = 0; // 根文件夹ID
+    public static final int ID_TEMPARAY_FOLDER = -1; // 临时文件夹ID
+    public static final int ID_CALL_RECORD_FOLDER = -2; // 通话记录夹ID
+    public static final int ID_TRASH_FOLER = -3; // 垃圾文件夹ID
+
+    // Intent额外参数
+    public static final String INTENT_EXTRA_ALERT_DATE = "net.micode.notes.alert_date"; // 警报日期
+    public static final String INTENT_EXTRA_BACKGROUND_ID = "net.micode.notes.background_color_id"; // 背景颜色ID
+    public static final String INTENT_EXTRA_WIDGET_ID = "net.micode.notes.widget_id"; // 小部件ID
+    public static final String INTENT_EXTRA_WIDGET_TYPE = "net.micode.notes.widget_type"; // 小部件类型
+    public static final String INTENT_EXTRA_FOLDER_ID = "net.micode.notes.folder_id"; // 文件夹ID
+    public static final String INTENT_EXTRA_CALL_DATE = "net.micode.notes.call_date"; // 通话日期
+
+    public static final int TYPE_WIDGET_INVALIDE = -1; // 无效小部件类型
+    public static final int TYPE_WIDGET_2X = 0; // 2x小部件类型
+    public static final int TYPE_WIDGET_4X = 1; // 4x小部件类型
+
+    // 数据常量类
+    public static class DataConstants {
+        public static final String NOTE = TextNote.CONTENT_ITEM_TYPE; // 笔记类型
+        public static final String CALL_NOTE = CallNote.CONTENT_ITEM_TYPE; // 通话记录类型
+    }
+
+    /**
+     * 查询所有笔记和文件夹的URI
+     */
+    public static final Uri CONTENT_NOTE_URI = Uri.parse("content://" + AUTHORITY + "/note"); // 笔记URI
+
+    /**
+     * 查询数据的URI
+     */
+    public static final Uri CONTENT_DATA_URI = Uri.parse("content://" + AUTHORITY + "/data"); // 数据URI
+
+    // 笔记列接口
+    public interface NoteColumns {
+        /**
+         * 行的唯一ID
+         * <P> 类型: INTEGER (long) </P>
+         */
+        public static final String ID = "_id"; // ID列
+
+        /**
+         * 笔记或文件夹的父ID
+         * <P> 类型: INTEGER (long) </P>
+         */
+        public static final String PARENT_ID = "parent_id"; // 父ID列
+
+        /**
+         * 笔记或文件夹的创建日期
+         * <P> 类型: INTEGER (long) </P>
+         */
+        public static final String CREATED_DATE = "created_date"; // 创建日期列
+
+        /**
+         * 最近修改日期
+         * <P> 类型: INTEGER (long) </P>
+         */
+        public static final String MODIFIED_DATE = "modified_date"; // 修改日期列
+
+        /**
+         * 警报日期
+         * <P> 类型: INTEGER (long) </P>
+         */
+        public static final String ALERTED_DATE = "alert_date"; // 警报日期列
+
+        /**
+         * 文件夹名称或笔记文本内容
+         * <P> 类型: TEXT </P>
+         */
+        public static final String SNIPPET = "snippet"; // 笔记内容列
+
+        /**
+         * 笔记的小部件ID
+         * <P> 类型: INTEGER (long) </P>
+         */
+        public static final String WIDGET_ID = "widget_id"; // 小部件ID列
+
+        /**
+         * 笔记的小部件类型
+         * <P> 类型: INTEGER (long) </P>
+         */
+        public static final String WIDGET_TYPE = "widget_type"; // 小部件类型列
+
+        /**
+         * 笔记背景颜色的ID
+         * <P> 类型: INTEGER (long) </P>
+         */
+        public static final String BG_COLOR_ID = "bg_color_id"; // 背景颜色ID列
+
+        /**
+         * 文本笔记没有附件，多媒体笔记至少有一个附件
+         * <P> 类型: INTEGER </P>
+         */
+        public static final String HAS_ATTACHMENT = "has_attachment"; // 附件列
+
+        /**
+         * 文件夹中的笔记数量
+         * <P> 类型: INTEGER (long) </P>
+         */
+        public static final String NOTES_COUNT = "notes_count"; // 笔记数量列
+
+        /**
+         * 文件类型: 文件夹或笔记
+         * <P> 类型: INTEGER </P>
+         */
+        public static final String TYPE = "type"; // 类型列
+
+        /**
+         * 最后同步ID
+         * <P> 类型: INTEGER (long) </P>
+         */
+        public static final String SYNC_ID = "sync_id"; // 同步ID列
+
+        /**
+         * 标记本地是否已修改
+         * <P> 类型: INTEGER </P>
+         */
+        public static final String LOCAL_MODIFIED = "local_modified"; // 本地修改标记列
+
+        /**
+         * 移动到临时文件夹之前的原父ID
+         * <P> 类型: INTEGER </P>
+         */
+        public static final String ORIGIN_PARENT_ID = "origin_parent_id"; // 原父ID列
+
+        /**
+         * gtask ID
+         * <P> 类型: TEXT </P>
+         */
+        public static final String GTASK_ID = "gtask_id"; // gtask ID列
+
+        /**
+         * 版本号
+         * <P> 类型: INTEGER (long) </P>
+         */
+        public static final String VERSION = "version"; // 版本列
+    }
+
+    // 数据列接口
+    public interface DataColumns {
+        /**
+         * 行的唯一ID
+         * <P> 类型: INTEGER (long) </P>
+         */
+        public static final String ID = "_id"; // ID列
+
+        /**
+         * 此行表示的项目的MIME类型
+         * <P> 类型: Text </P>
+         */
+        public static final String MIME_TYPE = "mime_type"; // MIME类型列
+
+        /**
+         * 此数据所属的笔记的引用ID
+         * <P> 类型: INTEGER (long) </P>
+         */
+        public static final String NOTE_ID = "note_id"; // 笔记ID列
+
+        /**
+         * 笔记或文件夹的创建日期
+         * <P> 类型: INTEGER (long) </P>
+         */
+        public static final String CREATED_DATE = "created_date"; // 创建日期列
+
+        /**
+         * 最新修改日期
+         * <P> 类型: INTEGER (long) </P>
+         */
+        public static final String MODIFIED_DATE = "modified_date"; // 修改日期列
+
+        /**
+         * 数据的内容
+         * <P> 类型: TEXT </P>
+         */
+        public static final String CONTENT = "content"; // 内容列
+
+        /**
+         * 通用数据列，含义是 {@link #MIMETYPE} 特定，使用于
+         * 整数数据类型
+         * <P> 类型: INTEGER </P>
+         */
+        public static final String DATA1 = "data1"; // 数据列1
+
+        /**
+         * 通用数据列，含义是 {@link #MIMETYPE} 特定，使用于
+         * 整数数据类型
+         * <P> 类型: INTEGER </P>
+         */
+        public static final String DATA2 = "data2"; // 数据列2
+
+        /**
+         * 通用数据列，含义是 {@link #MIMETYPE} 特定，使用于
+         * 文本数据类型
+         * <P> 类型: TEXT </P>
+         */
+        public static final String DATA3 = "data3"; // 数据列3
+
+        /**
+         * 通用数据列，含义是 {@link #MIMETYPE} 特定，使用于
+         * 文本数据类型
+         * <P> 类型: TEXT </P>
+         */
+        public static final String DATA4 = "data4"; // 数据列4
+
+        /**
+         * 通用数据列，含义是 {@link #MIMETYPE} 特定，使用于
+         * 文本数据类型
+         * <P> 类型: TEXT </P>
+         */
+        public static final String DATA5 = "data5"; // 数据列5
+    }
+
+    // 文本笔记类
+    public static final class TextNote implements DataColumns {
+        /**
+         * 指示文本是否处于检查列表模式
+         * <P> 类型: Integer 1: 检查列表模式 0: 正常模式 </P>
+         */
+        public static final String MODE = DATA1; // 模式列
+
+        public static final int MODE_CHECK_LIST = 1; // 检查列表模式标记
+
+        public static final String CONTENT_TYPE = "vnd.android.cursor.dir/text_note"; // 内容类型
+
+        public static final String CONTENT_ITEM_TYPE = "vnd.android.cursor.item/text_note"; // 项目内容类型
+
+        public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY + "/text_note"); // 文本笔记URI
+    }
+
+    // 通话记录类
+    public static final class CallNote implements DataColumns {
+        /**
+         * 此记录的通话日期
+         * <P> 类型: INTEGER (long) </P>
+         */
+        public static final String CALL_DATE = DATA1; // 通话日期列
+
+        /**
+         * 此记录的电话号码
+         * <P> 类型: TEXT </P>
+         */
+        public static final String PHONE_NUMBER = DATA3; // 电话号码列
+
+        public static final String CONTENT_TYPE = "vnd.android.cursor.dir/call_note"; // 内容类型
+
+        public static final String CONTENT_ITEM_TYPE = "vnd.android.cursor.item/call_note"; // 项目内容类型
+
+        public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY + "/call_note"); // 通话记录URI
+    }
+}
\ No newline at end of file
diff --git a/src/NotesDatabaseHelper.java b/src/NotesDatabaseHelper.java
new file mode 100644
index 0000000..ef8f1d4
--- /dev/null
+++ b/src/NotesDatabaseHelper.java
@@ -0,0 +1,348 @@
+/*
+ * 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; // 导入内容值类
+import android.content.Context; // 导入上下文类
+import android.database.sqlite.SQLiteDatabase; // 导入SQLite数据库类
+import android.database.sqlite.SQLiteOpenHelper; // 导入SQLiteOpenHelper类
+import android.util.Log; // 导入日志类
+
+import net.micode.notes.data.Notes.DataColumns; // 导入数据列类
+import net.micode.notes.data.Notes.DataConstants; // 导入数据常量类
+import net.micode.notes.data.Notes.NoteColumns; // 导入笔记列类
+
+// 笔记数据库帮助类
+public class NotesDatabaseHelper extends SQLiteOpenHelper {
+    private static final String DB_NAME = "note.db"; // 数据库名字
+
+    private static final int DB_VERSION = 4; // 数据库版本号
+
+    // 表名接口
+    public interface TABLE {
+        public static final String NOTE = "note"; // 笔记表名
+
+        public static final String DATA = "data"; // 数据表名
+    }
+
+    private static final String TAG = "NotesDatabaseHelper"; // 日志标签
+
+    private static NotesDatabaseHelper mInstance; // 单例实例
+
+    // 创建笔记表的 SQL 语句
+    private static final String CREATE_NOTE_TABLE_SQL =
+            "CREATE TABLE " + TABLE.NOTE + "(" +
+                    NoteColumns.ID + " INTEGER PRIMARY KEY," +
+                    NoteColumns.PARENT_ID + " INTEGER NOT NULL DEFAULT 0," +
+                    NoteColumns.ALERTED_DATE + " INTEGER NOT NULL DEFAULT 0," +
+                    NoteColumns.BG_COLOR_ID + " INTEGER NOT NULL DEFAULT 0," +
+                    NoteColumns.CREATED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
+                    NoteColumns.HAS_ATTACHMENT + " INTEGER NOT NULL DEFAULT 0," +
+                    NoteColumns.MODIFIED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
+                    NoteColumns.NOTES_COUNT + " INTEGER NOT NULL DEFAULT 0," +
+                    NoteColumns.SNIPPET + " TEXT NOT NULL DEFAULT ''," +
+                    NoteColumns.TYPE + " INTEGER NOT NULL DEFAULT 0," +
+                    NoteColumns.WIDGET_ID + " INTEGER NOT NULL DEFAULT 0," +
+                    NoteColumns.WIDGET_TYPE + " INTEGER NOT NULL DEFAULT -1," +
+                    NoteColumns.SYNC_ID + " INTEGER NOT NULL DEFAULT 0," +
+                    NoteColumns.LOCAL_MODIFIED + " INTEGER NOT NULL DEFAULT 0," +
+                    NoteColumns.ORIGIN_PARENT_ID + " INTEGER NOT NULL DEFAULT 0," +
+                    NoteColumns.GTASK_ID + " TEXT NOT NULL DEFAULT ''," +
+                    NoteColumns.VERSION + " INTEGER NOT NULL DEFAULT 0" +
+                    ")";
+
+    // 创建数据表的 SQL 语句
+    private static final String CREATE_DATA_TABLE_SQL =
+            "CREATE TABLE " + TABLE.DATA + "(" +
+                    DataColumns.ID + " INTEGER PRIMARY KEY," +
+                    DataColumns.MIME_TYPE + " TEXT NOT NULL," +
+                    DataColumns.NOTE_ID + " INTEGER NOT NULL DEFAULT 0," +
+                    NoteColumns.CREATED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
+                    NoteColumns.MODIFIED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
+                    DataColumns.CONTENT + " TEXT NOT NULL DEFAULT ''," +
+                    DataColumns.DATA1 + " INTEGER," +
+                    DataColumns.DATA2 + " INTEGER," +
+                    DataColumns.DATA3 + " TEXT NOT NULL DEFAULT ''," +
+                    DataColumns.DATA4 + " TEXT NOT NULL DEFAULT ''," +
+                    DataColumns.DATA5 + " TEXT NOT NULL DEFAULT ''" +
+                    ")";
+
+    // 创建数据表的 NOTE_ID 索引的 SQL 语句
+    private static final String CREATE_DATA_NOTE_ID_INDEX_SQL =
+            "CREATE INDEX IF NOT EXISTS note_id_index ON " +
+                    TABLE.DATA + "(" + DataColumns.NOTE_ID + ");";
+
+    // 增加文件夹笔记计数的触发器 SQL 语句
+    private static final String NOTE_INCREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =
+            "CREATE TRIGGER increase_folder_count_on_update " +
+                    " AFTER UPDATE OF " + NoteColumns.PARENT_ID + " ON " + TABLE.NOTE +
+                    " BEGIN " +
+                    "  UPDATE " + TABLE.NOTE +
+                    "   SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + " + 1" +
+                    "  WHERE " + NoteColumns.ID + "=new." + NoteColumns.PARENT_ID + ";" +
+                    " END";
+
+    // 减少文件夹笔记计数的触发器 SQL 语句
+    private static final String NOTE_DECREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =
+            "CREATE TRIGGER decrease_folder_count_on_update " +
+                    " AFTER UPDATE OF " + NoteColumns.PARENT_ID + " ON " + TABLE.NOTE +
+                    " BEGIN " +
+                    "  UPDATE " + TABLE.NOTE +
+                    "   SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + "-1" +
+                    "  WHERE " + NoteColumns.ID + "=old." + NoteColumns.PARENT_ID +
+                    "  AND " + NoteColumns.NOTES_COUNT + ">0" + ";" +
+                    " END";
+
+    // 插入新笔记时增加文件夹笔记计数的触发器 SQL 语句
+    private static final String NOTE_INCREASE_FOLDER_COUNT_ON_INSERT_TRIGGER =
+            "CREATE TRIGGER increase_folder_count_on_insert " +
+                    " AFTER INSERT ON " + TABLE.NOTE +
+                    " BEGIN " +
+                    "  UPDATE " + TABLE.NOTE +
+                    "   SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + " + 1" +
+                    "  WHERE " + NoteColumns.ID + "=new." + NoteColumns.PARENT_ID + ";" +
+                    " END";
+
+    // 从文件夹中删除笔记时减少文件夹笔记计数的触发器 SQL 语句
+    private static final String NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER =
+            "CREATE TRIGGER decrease_folder_count_on_delete " +
+                    " AFTER DELETE ON " + TABLE.NOTE +
+                    " BEGIN " +
+                    "  UPDATE " + TABLE.NOTE +
+                    "   SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + "-1" +
+                    "  WHERE " + NoteColumns.ID + "=old." + NoteColumns.PARENT_ID +
+                    "  AND " + NoteColumns.NOTES_COUNT + ">0;" +
+                    " END";
+
+    // 插入数据时更新笔记内容的触发器 SQL 语句
+    private static final String DATA_UPDATE_NOTE_CONTENT_ON_INSERT_TRIGGER =
+            "CREATE TRIGGER update_note_content_on_insert " +
+                    " AFTER INSERT ON " + TABLE.DATA +
+                    " WHEN new." + DataColumns.MIME_TYPE + "='" + DataConstants.NOTE + "'" +
+                    " BEGIN" +
+                    "  UPDATE " + TABLE.NOTE +
+                    "   SET " + NoteColumns.SNIPPET + "=new." + DataColumns.CONTENT +
+                    "  WHERE " + NoteColumns.ID + "=new." + DataColumns.NOTE_ID + ";" +
+                    " END";
+
+    // 更新数据时更新笔记内容的触发器 SQL 语句
+    private static final String DATA_UPDATE_NOTE_CONTENT_ON_UPDATE_TRIGGER =
+            "CREATE TRIGGER update_note_content_on_update " +
+                    " AFTER UPDATE ON " + TABLE.DATA +
+                    " WHEN old." + DataColumns.MIME_TYPE + "='" + DataConstants.NOTE + "'" +
+                    " BEGIN" +
+                    "  UPDATE " + TABLE.NOTE +
+                    "   SET " + NoteColumns.SNIPPET + "=new." + DataColumns.CONTENT +
+                    "  WHERE " + NoteColumns.ID + "=new." + DataColumns.NOTE_ID + ";" +
+                    " END";
+
+    // 删除数据时更新笔记内容的触发器 SQL 语句
+    private static final String DATA_UPDATE_NOTE_CONTENT_ON_DELETE_TRIGGER =
+            "CREATE TRIGGER update_note_content_on_delete " +
+                    " AFTER delete ON " + TABLE.DATA +
+                    " WHEN old." + DataColumns.MIME_TYPE + "='" + DataConstants.NOTE + "'" +
+                    " BEGIN" +
+                    "  UPDATE " + TABLE.NOTE +
+                    "   SET " + NoteColumns.SNIPPET + "=''" +
+                    "  WHERE " + NoteColumns.ID + "=old." + DataColumns.NOTE_ID + ";" +
+                    " END";
+
+    // 删除已删除笔记的数据的触发器 SQL 语句
+    private static final String NOTE_DELETE_DATA_ON_DELETE_TRIGGER =
+            "CREATE TRIGGER delete_data_on_delete " +
+                    " AFTER DELETE ON " + TABLE.NOTE +
+                    " BEGIN" +
+                    "  DELETE FROM " + TABLE.DATA +
+                    "   WHERE " + DataColumns.NOTE_ID + "=old." + NoteColumns.ID + ";" +
+                    " END";
+
+    // 删除已删除文件夹中的笔记的触发器 SQL 语句
+    private static final String FOLDER_DELETE_NOTES_ON_DELETE_TRIGGER =
+            "CREATE TRIGGER folder_delete_notes_on_delete " +
+                    " AFTER DELETE ON " + TABLE.NOTE +
+                    " BEGIN" +
+                    "  DELETE FROM " + TABLE.NOTE +
+                    "   WHERE " + NoteColumns.PARENT_ID + "=old." + NoteColumns.ID + ";" +
+                    " END";
+
+    // 移动到回收站文件夹的笔记的触发器 SQL 语句
+    private static final String FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER =
+            "CREATE TRIGGER folder_move_notes_on_trash " +
+                    " AFTER UPDATE ON " + TABLE.NOTE +
+                    " WHEN new." + NoteColumns.PARENT_ID + "=" + Notes.ID_TRASH_FOLER +
+                    " BEGIN" +
+                    "  UPDATE " + TABLE.NOTE +
+                    "   SET " + NoteColumns.PARENT_ID + "=" + Notes.ID_TRASH_FOLER +
+                    "  WHERE " + NoteColumns.PARENT_ID + "=old." + NoteColumns.ID + ";" +
+                    " END";
+
+    // 构造函数
+    public NotesDatabaseHelper(Context context) {
+        super(context, DB_NAME, null, DB_VERSION); // 调用父类构造函数
+    }
+
+    // 创建笔记表
+    public void createNoteTable(SQLiteDatabase db) {
+        db.execSQL(CREATE_NOTE_TABLE_SQL); // 执行创建笔记表的 SQL
+        reCreateNoteTableTriggers(db); // 重新创建笔记表触发器
+        createSystemFolder(db); // 创建系统文件夹
+        Log.d(TAG, "note table has been created"); // 打印日志
+    }
+
+    // 重新创建笔记表触发器
+    private void reCreateNoteTableTriggers(SQLiteDatabase db) {
+        db.execSQL("DROP TRIGGER IF EXISTS increase_folder_count_on_update"); // 删除触发器
+        db.execSQL("DROP TRIGGER IF EXISTS decrease_folder_count_on_update"); // 删除触发器
+        db.execSQL("DROP TRIGGER IF EXISTS decrease_folder_count_on_delete"); // 删除触发器
+        db.execSQL("DROP TRIGGER IF EXISTS delete_data_on_delete"); // 删除触发器
+        db.execSQL("DROP TRIGGER IF EXISTS increase_folder_count_on_insert"); // 删除触发器
+        db.execSQL("DROP TRIGGER IF EXISTS folder_delete_notes_on_delete"); // 删除触发器
+        db.execSQL("DROP TRIGGER IF EXISTS folder_move_notes_on_trash"); // 删除触发器
+
+        db.execSQL(NOTE_INCREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER); // 创建触发器
+        db.execSQL(NOTE_DECREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER); // 创建触发器
+        db.execSQL(NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER); // 创建触发器
+        db.execSQL(NOTE_DELETE_DATA_ON_DELETE_TRIGGER); // 创建触发器
+        db.execSQL(NOTE_INCREASE_FOLDER_COUNT_ON_INSERT_TRIGGER); // 创建触发器
+        db.execSQL(FOLDER_DELETE_NOTES_ON_DELETE_TRIGGER); // 创建触发器
+        db.execSQL(FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER); // 创建触发器
+    }
+
+    // 创建系统文件夹
+    private void createSystemFolder(SQLiteDatabase db) {
+        ContentValues values = new ContentValues(); // 创建内容值对象
+
+        // 通话记录文件夹的记录
+        values.put(NoteColumns.ID, Notes.ID_CALL_RECORD_FOLDER);
+        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM); // 系统类型
+        db.insert(TABLE.NOTE, null, values); // 插入到笔记表
+
+        // 默认根文件夹
+        values.clear(); // 清空内容值对象
+        values.put(NoteColumns.ID, Notes.ID_ROOT_FOLDER);
+        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM); // 系统类型
+        db.insert(TABLE.NOTE, null, values); // 插入到笔记表
+
+        // 临时文件夹用于移动笔记
+        values.clear(); // 清空内容值对象
+        values.put(NoteColumns.ID, Notes.ID_TEMPARAY_FOLDER);
+        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM); // 系统类型
+        db.insert(TABLE.NOTE, null, values); // 插入到笔记表
+
+        // 创建回收站文件夹
+        values.clear(); // 清空内容值对象
+        values.put(NoteColumns.ID, Notes.ID_TRASH_FOLER);
+        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM); // 系统类型
+        db.insert(TABLE.NOTE, null, values); // 插入到笔记表
+    }
+
+    // 创建数据表
+    public void createDataTable(SQLiteDatabase db) {
+        db.execSQL(CREATE_DATA_TABLE_SQL); // 执行创建数据表的 SQL
+        reCreateDataTableTriggers(db); // 重新创建数据表触发器
+        db.execSQL(CREATE_DATA_NOTE_ID_INDEX_SQL); // 创建数据表索引
+        Log.d(TAG, "data table has been created"); // 打印日志
+    }
+
+    // 重新创建数据表触发器
+    private void reCreateDataTableTriggers(SQLiteDatabase db) {
+        db.execSQL("DROP TRIGGER IF EXISTS update_note_content_on_insert"); // 删除触发器
+        db.execSQL("DROP TRIGGER IF EXISTS update_note_content_on_update"); // 删除触发器
+        db.execSQL("DROP TRIGGER IF EXISTS update_note_content_on_delete"); // 删除触发器
+
+        db.execSQL(DATA_UPDATE_NOTE_CONTENT_ON_INSERT_TRIGGER); // 创建触发器
+        db.execSQL(DATA_UPDATE_NOTE_CONTENT_ON_UPDATE_TRIGGER); // 创建触发器
+        db.execSQL(DATA_UPDATE_NOTE_CONTENT_ON_DELETE_TRIGGER); // 创建触发器
+    }
+
+    // 获取单例实例
+    static synchronized NotesDatabaseHelper getInstance(Context context) {
+        if (mInstance == null) { // 如果实例为空
+            mInstance = new NotesDatabaseHelper(context); // 创建新实例
+        }
+        return mInstance; // 返回实例
+    }
+
+    @Override
+    public void onCreate(SQLiteDatabase db) {
+        createNoteTable(db); // 创建笔记表
+        createDataTable(db); // 创建数据表
+    }
+
+    @Override
+    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
+        boolean reCreateTriggers = false; // 触发器是否需要重建
+        boolean skipV2 = false; // 是否跳过 V2 升级
+
+        if (oldVersion == 1) {
+            upgradeToV2(db); // 升级到 V2
+            skipV2 = true; // 标记为跳过 V2 升级
+            oldVersion++; // 增加版本号
+        }
+
+        if (oldVersion == 2 && !skipV2) {
+            upgradeToV3(db); // 升级到 V3
+            reCreateTriggers = true; // 标记为需要重建触发器
+            oldVersion++; // 增加版本号
+        }
+
+        if (oldVersion == 3) {
+            upgradeToV4(db); // 升级到 V4
+            oldVersion++; // 增加版本号
+        }
+
+        if (reCreateTriggers) {
+            reCreateNoteTableTriggers(db); // 重新创建笔记表触发器
+            reCreateDataTableTriggers(db); // 重新创建数据表触发器
+        }
+
+        if (oldVersion != newVersion) {
+            throw new IllegalStateException("Upgrade notes database to version " + newVersion
+                    + " fails"); // 抛出异常
+        }
+    }
+
+    // 升级到 V2
+    private void upgradeToV2(SQLiteDatabase db) {
+        db.execSQL("DROP TABLE IF EXISTS " + TABLE.NOTE); // 删除笔记表
+        db.execSQL("DROP TABLE IF EXISTS " + TABLE.DATA); // 删除数据表
+        createNoteTable(db); // 创建笔记表
+        createDataTable(db); // 创建数据表
+    }
+
+    // 升级到 V3
+    private void upgradeToV3(SQLiteDatabase db) {
+        // 删除未使用的触发器
+        db.execSQL("DROP TRIGGER IF EXISTS update_note_modified_date_on_insert");
+        db.execSQL("DROP TRIGGER IF EXISTS update_note_modified_date_on_delete");
+        db.execSQL("DROP TRIGGER IF EXISTS update_note_modified_date_on_update");
+        // 添加 gtask id 列
+        db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.GTASK_ID
+                + " TEXT NOT NULL DEFAULT ''");
+        // 添加回收站系统文件夹
+        ContentValues values = new ContentValues(); // 创建内容值对象
+        values.put(NoteColumns.ID, Notes.ID_TRASH_FOLER); // 设置文件夹 ID
+        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM); // 系统类型
+        db.insert(TABLE.NOTE, null, values); // 插入到笔记表
+    }
+
+    // 升级到 V4
+    private void upgradeToV4(SQLiteDatabase db) {
+        db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.VERSION
+                + " INTEGER NOT NULL DEFAULT 0"); // 添加版本列
+    }
+}
\ No newline at end of file
diff --git a/src/NotesPreferenceActivity.java b/src/NotesPreferenceActivity.java
new file mode 100644
index 0000000..3fca75a
--- /dev/null
+++ b/src/NotesPreferenceActivity.java
@@ -0,0 +1,384 @@
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.micode.notes.ui;
+
+import android.accounts.Account; // 导入账户类
+import android.accounts.AccountManager; // 导入账户管理类
+import android.app.ActionBar; // 导入动作栏类
+import android.app.AlertDialog; // 导入警告对话框类
+import android.content.BroadcastReceiver; // 导入广播接收器类
+import android.content.ContentValues; // 导入内容值类
+import android.content.Context; // 导入上下文类
+import android.content.DialogInterface; // 导入对话框接口类
+import android.content.Intent; // 导入意图类
+import android.content.IntentFilter; // 导入意图过滤器类
+import android.content.SharedPreferences; // 导入共享偏好类
+import android.os.Bundle; // 导入捆绑类
+import android.preference.Preference; // 导入偏好类
+import android.preference.Preference.OnPreferenceClickListener; // 导入偏好点击监听器
+import android.preference.PreferenceActivity; // 导入偏好活动类
+import android.preference.PreferenceCategory; // 导入偏好类别类
+import android.text.TextUtils; // 导入文本工具类
+import android.text.format.DateFormat; // 导入日期格式化类
+import android.view.LayoutInflater; // 导入布局填充器类
+import android.view.Menu; // 导入菜单类
+import android.view.MenuItem; // 导入菜单项类
+import android.view.View; // 导入视图类
+import android.widget.Button; // 导入按钮类
+import android.widget.TextView; // 导入文本视图类
+import android.widget.Toast; // 导入吐司类
+
+import net.micode.notes.R; // 导入资源类
+import net.micode.notes.data.Notes; // 导入笔记数据类
+import net.micode.notes.data.Notes.NoteColumns; // 导入笔记列类
+import net.micode.notes.gtask.remote.GTaskSyncService; // 导入GTask同步服务类
+
+public class NotesPreferenceActivity extends PreferenceActivity {
+    public static final String PREFERENCE_NAME = "notes_preferences"; // 偏好名称
+
+    public static final String PREFERENCE_SYNC_ACCOUNT_NAME = "pref_key_account_name"; // 同步账户名称偏好键
+
+    public static final String PREFERENCE_LAST_SYNC_TIME = "pref_last_sync_time"; // 最后同步时间偏好键
+
+    public static final String PREFERENCE_SET_BG_COLOR_KEY = "pref_key_bg_random_appear"; // 背景颜色偏好键
+
+    private static final String PREFERENCE_SYNC_ACCOUNT_KEY = "pref_sync_account_key"; // 同步账户偏好键
+
+    private static final String AUTHORITIES_FILTER_KEY = "authorities"; // 权限过滤键
+
+    private PreferenceCategory mAccountCategory; // 账户类别
+
+    private GTaskReceiver mReceiver; // GTask接收器
+
+    private Account[] mOriAccounts; // 原始账户数组
+
+    private boolean mHasAddedAccount; // 是否添加账户标志
+
+    @Override
+    protected void onCreate(Bundle icicle) {
+        super.onCreate(icicle);
+
+        // 使用应用图标进行导航
+        getActionBar().setDisplayHomeAsUpEnabled(true);
+
+        addPreferencesFromResource(R.xml.preferences); // 从资源加载偏好设置
+        mAccountCategory = (PreferenceCategory) findPreference(PREFERENCE_SYNC_ACCOUNT_KEY); // 查找账户类别
+        mReceiver = new GTaskReceiver(); // 初始化GTask接收器
+        IntentFilter filter = new IntentFilter(); // 创建意图过滤器
+        filter.addAction(GTaskSyncService.GTASK_SERVICE_BROADCAST_NAME); // 添加GTask服务广播名称
+        registerReceiver(mReceiver, filter); // 注册接收器
+
+        mOriAccounts = null; // 初始化原始账户
+        View header = LayoutInflater.from(this).inflate(R.layout.settings_header, null); // 填充设置头部视图
+        getListView().addHeaderView(header, null, true); // 添加头部视图
+    }
+
+    @Override
+    protected void onResume() {
+        super.onResume();
+
+        // 如果用户添加了新账户，则需要自动设置同步账户
+        if (mHasAddedAccount) {
+            Account[] accounts = getGoogleAccounts(); // 获取Google账户
+            if (mOriAccounts != null && accounts.length > mOriAccounts.length) {
+                for (Account accountNew : accounts) {
+                    boolean found = false; // 标志账户是否找到
+                    for (Account accountOld : mOriAccounts) {
+                        if (TextUtils.equals(accountOld.name, accountNew.name)) {
+                            found = true; // 找到账户
+                            break;
+                        }
+                    }
+                    if (!found) {
+                        setSyncAccount(accountNew.name); // 设置同步账户
+                        break; // 退出循环
+                    }
+                }
+            }
+        }
+
+        refreshUI(); // 刷新用户界面
+    }
+
+    @Override
+    protected void onDestroy() {
+        if (mReceiver != null) {
+            unregisterReceiver(mReceiver); // 注销接收器
+        }
+        super.onDestroy();
+    }
+
+    private void loadAccountPreference() {
+        mAccountCategory.removeAll(); // 移除所有账户偏好设置
+
+        Preference accountPref = new Preference(this); // 创建账户偏好设置
+        final String defaultAccount = getSyncAccountName(this); // 获取同步账户名称
+        accountPref.setTitle(getString(R.string.preferences_account_title)); // 设置标题
+        accountPref.setSummary(getString(R.string.preferences_account_summary)); // 设置摘要
+        accountPref.setOnPreferenceClickListener(new OnPreferenceClickListener() { // 设置点击监听器
+            public boolean onPreferenceClick(Preference preference) {
+                if (!GTaskSyncService.isSyncing()) { // 如果没有正在同步
+                    if (TextUtils.isEmpty(defaultAccount)) {
+                        // 第一次设置账户
+                        showSelectAccountAlertDialog(); // 显示选择账户对话框
+                    } else {
+                        // 如果账户已经设置，需要提醒用户风险
+                        showChangeAccountConfirmAlertDialog(); // 显示更改账户确认对话框
+                    }
+                } else {
+                    Toast.makeText(NotesPreferenceActivity.this,
+                                    R.string.preferences_toast_cannot_change_account, Toast.LENGTH_SHORT) // 显示不能更改账户的提示
+                            .show();
+                }
+                return true; // 返回true表示事件已处理
+            }
+        });
+
+        mAccountCategory.addPreference(accountPref); // 添加账户偏好设置
+    }
+
+    private void loadSyncButton() {
+        Button syncButton = (Button) findViewById(R.id.preference_sync_button); // 获取同步按钮
+        TextView lastSyncTimeView = (TextView) findViewById(R.id.prefenerece_sync_status_textview); // 获取最后同步时间视图
+
+        // 设置按钮状态
+        if (GTaskSyncService.isSyncing()) {
+            syncButton.setText(getString(R.string.preferences_button_sync_cancel)); // 设置按钮文本为取消同步
+            syncButton.setOnClickListener(new View.OnClickListener() { // 设置点击监听器
+                public void onClick(View v) {
+                    GTaskSyncService.cancelSync(NotesPreferenceActivity.this); // 取消同步
+                }
+            });
+        } else {
+            syncButton.setText(getString(R.string.preferences_button_sync_immediately)); // 设置按钮文本为立即同步
+            syncButton.setOnClickListener(new View.OnClickListener() { // 设置点击监听器
+                public void onClick(View v) {
+                    GTaskSyncService.startSync(NotesPreferenceActivity.this); // 开始同步
+                }
+            });
+        }
+        syncButton.setEnabled(!TextUtils.isEmpty(getSyncAccountName(this))); // 设置按钮是否可用
+
+        // 设置最后同步时间
+        if (GTaskSyncService.isSyncing()) {
+            lastSyncTimeView.setText(GTaskSyncService.getProgressString()); // 显示同步状态
+            lastSyncTimeView.setVisibility(View.VISIBLE); // 显示最后同步时间视图
+        } else {
+            long lastSyncTime = getLastSyncTime(this); // 获取最后同步时间
+            if (lastSyncTime != 0) {
+                lastSyncTimeView.setText(getString(R.string.preferences_last_sync_time,
+                        DateFormat.format(getString(R.string.preferences_last_sync_time_format),
+                                lastSyncTime))); // 显示格式化的最后同步时间
+                lastSyncTimeView.setVisibility(View.VISIBLE); // 显示最后同步时间视图
+            } else {
+                lastSyncTimeView.setVisibility(View.GONE); // 隐藏最后同步时间视图
+            }
+        }
+    }
+
+    private void refreshUI() {
+        loadAccountPreference(); // 加载账户偏好设置
+        loadSyncButton(); // 加载同步按钮
+    }
+
+    private void showSelectAccountAlertDialog() {
+        AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(this); // 创建对话框构建器
+
+        View titleView = LayoutInflater.from(this).inflate(R.layout.account_dialog_title, null); // 填充对话框标题视图
+        TextView titleTextView = (TextView) titleView.findViewById(R.id.account_dialog_title); // 获取标题文本视图
+        titleTextView.setText(getString(R.string.preferences_dialog_select_account_title)); // 设置标题文本
+        TextView subtitleTextView = (TextView) titleView.findViewById(R.id.account_dialog_subtitle); // 获取副标题文本视图
+        subtitleTextView.setText(getString(R.string.preferences_dialog_select_account_tips)); // 设置副标题文本
+
+        dialogBuilder.setCustomTitle(titleView); // 设置自定义标题
+        dialogBuilder.setPositiveButton(null, null); // 设置正面按钮
+
+        Account[] accounts = getGoogleAccounts(); // 获取Google账户
+        String defAccount = getSyncAccountName(this); // 获取同步账户名称
+
+        mOriAccounts = accounts; // 保存原始账户
+        mHasAddedAccount = false; // 重置添加账户标志
+
+        if (accounts.length > 0) {
+            CharSequence[] items = new CharSequence[accounts.length]; // 创建账户名称数组
+            final CharSequence[] itemMapping = items; // 保存账户名称映射
+            int checkedItem = -1; // 选中项索引
+            int index = 0; // 数组索引
+            for (Account account : accounts) {
+                if (TextUtils.equals(account.name, defAccount)) {
+                    checkedItem = index; // 如果是默认账户，设置checkedItem
+                }
+                items[index++] = account.name; // 添加账户名称
+            }
+            dialogBuilder.setSingleChoiceItems(items, checkedItem, // 设置单选项
+                    new DialogInterface.OnClickListener() {
+                        public void onClick(DialogInterface dialog, int which) {
+                            setSyncAccount(itemMapping[which].toString()); // 设置同步账户
+                            dialog.dismiss(); // 关闭对话框
+                            refreshUI(); // 刷新用户界面
+                        }
+                    });
+        }
+
+        View addAccountView = LayoutInflater.from(this).inflate(R.layout.add_account_text, null); // 填充添加账户视图
+        dialogBuilder.setView(addAccountView); // 设置对话框视图
+
+        final AlertDialog dialog = dialogBuilder.show(); // 显示对话框
+        addAccountView.setOnClickListener(new View.OnClickListener() { // 设置点击监听器
+            public void onClick(View v) {
+                mHasAddedAccount = true; // 设置添加账户标志
+                Intent intent = new Intent("android.settings.ADD_ACCOUNT_SETTINGS"); // 创建添加账户意图
+                intent.putExtra(AUTHORITIES_FILTER_KEY, new String[] {
+                        "gmail-ls" // 添加权限过滤
+                });
+                startActivityForResult(intent, -1); // 启动添加账户活动
+                dialog.dismiss(); // 关闭对话框
+            }
+        });
+    }
+
+    private void showChangeAccountConfirmAlertDialog() {
+        AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(this); // 创建对话框构建器
+
+        View titleView = LayoutInflater.from(this).inflate(R.layout.account_dialog_title, null); // 填充对话框标题视图
+        TextView titleTextView = (TextView) titleView.findViewById(R.id.account_dialog_title); // 获取标题文本视图
+        titleTextView.setText(getString(R.string.preferences_dialog_change_account_title,
+                getSyncAccountName(this))); // 设置标题文本
+        TextView subtitleTextView = (TextView) titleView.findViewById(R.id.account_dialog_subtitle); // 获取副标题文本视图
+        subtitleTextView.setText(getString(R.string.preferences_dialog_change_account_warn_msg)); // 设置副标题文本
+        dialogBuilder.setCustomTitle(titleView); // 设置自定义标题
+
+        CharSequence[] menuItemArray = new CharSequence[] {
+                getString(R.string.preferences_menu_change_account), // 更改账户
+                getString(R.string.preferences_menu_remove_account), // 移除账户
+                getString(R.string.preferences_menu_cancel) // 取消
+        };
+        dialogBuilder.setItems(menuItemArray, new DialogInterface.OnClickListener() { // 设置对话框项
+            public void onClick(DialogInterface dialog, int which) {
+                if (which == 0) {
+                    showSelectAccountAlertDialog(); // 显示选择账户对话框
+                } else if (which == 1) {
+                    removeSyncAccount(); // 移除同步账户
+                    refreshUI(); // 刷新用户界面
+                }
+            }
+        });
+        dialogBuilder.show(); // 显示对话框
+    }
+
+    private Account[] getGoogleAccounts() {
+        AccountManager accountManager = AccountManager.get(this); // 获取账户管理器
+        return accountManager.getAccountsByType("com.google"); // 返回Google账户
+    }
+
+    private void setSyncAccount(String account) {
+        if (!getSyncAccountName(this).equals(account)) {
+            SharedPreferences settings = getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE); // 获取共享偏好设置
+            SharedPreferences.Editor editor = settings.edit(); // 创建编辑器
+            if (account != null) {
+                editor.putString(PREFERENCE_SYNC_ACCOUNT_NAME, account); // 设置同步账户名称
+            } else {
+                editor.putString(PREFERENCE_SYNC_ACCOUNT_NAME, ""); // 清空同步账户名称
+            }
+            editor.commit(); // 提交更改
+
+            // 清除最后同步时间
+            setLastSyncTime(this, 0);
+
+            // 清除本地GTask相关信息
+            new Thread(new Runnable() {
+                public void run() {
+                    ContentValues values = new ContentValues(); // 创建内容值
+                    values.put(NoteColumns.GTASK_ID, ""); // 清空GTASK_ID
+                    values.put(NoteColumns.SYNC_ID, 0); // 清空SYNC_ID
+                    getContentResolver().update(Notes.CONTENT_NOTE_URI, values, null, null); // 更新笔记内容
+                }
+            }).start();
+
+            Toast.makeText(NotesPreferenceActivity.this,
+                    getString(R.string.preferences_toast_success_set_accout, account), // 显示设置成功的提示
+                    Toast.LENGTH_SHORT).show();
+        }
+    }
+
+    private void removeSyncAccount() {
+        SharedPreferences settings = getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE); // 获取共享偏好设置
+        SharedPreferences.Editor editor = settings.edit(); // 创建编辑器
+        if (settings.contains(PREFERENCE_SYNC_ACCOUNT_NAME)) {
+            editor.remove(PREFERENCE_SYNC_ACCOUNT_NAME); // 移除同步账户名称
+        }
+        if (settings.contains(PREFERENCE_LAST_SYNC_TIME)) {
+            editor.remove(PREFERENCE_LAST_SYNC_TIME); // 移除最后同步时间
+        }
+        editor.commit(); // 提交更改
+
+        // 清除本地GTask相关信息
+        new Thread(new Runnable() {
+            public void run() {
+                ContentValues values = new ContentValues(); // 创建内容值
+                values.put(NoteColumns.GTASK_ID, ""); // 清空GTASK_ID
+                values.put(NoteColumns.SYNC_ID, 0); // 清空SYNC_ID
+                getContentResolver().update(Notes.CONTENT_NOTE_URI, values, null, null); // 更新笔记内容
+            }
+        }).start();
+    }
+
+    public static String getSyncAccountName(Context context) {
+        SharedPreferences settings = context.getSharedPreferences(PREFERENCE_NAME,
+                Context.MODE_PRIVATE); // 获取共享偏好设置
+        return settings.getString(PREFERENCE_SYNC_ACCOUNT_NAME, ""); // 返回同步账户名称
+    }
+
+    public static void setLastSyncTime(Context context, long time) {
+        SharedPreferences settings = context.getSharedPreferences(PREFERENCE_NAME,
+                Context.MODE_PRIVATE); // 获取共享偏好设置
+        SharedPreferences.Editor editor = settings.edit(); // 创建编辑器
+        editor.putLong(PREFERENCE_LAST_SYNC_TIME, time); // 设置最后同步时间
+        editor.commit(); // 提交更改
+    }
+
+    public static long getLastSyncTime(Context context) {
+        SharedPreferences settings = context.getSharedPreferences(PREFERENCE_NAME,
+                Context.MODE_PRIVATE); // 获取共享偏好设置
+        return settings.getLong(PREFERENCE_LAST_SYNC_TIME, 0); // 返回最后同步时间
+    }
+
+    private class GTaskReceiver extends BroadcastReceiver {
+
+        @Override
+        public void onReceive(Context context, Intent intent) {
+            refreshUI(); // 刷新用户界面
+            if (intent.getBooleanExtra(GTaskSyncService.GTASK_SERVICE_BROADCAST_IS_SYNCING, false)) {
+                TextView syncStatus = (TextView) findViewById(R.id.prefenerece_sync_status_textview); // 获取同步状态视图
+                syncStatus.setText(intent
+                        .getStringExtra(GTaskSyncService.GTASK_SERVICE_BROADCAST_PROGRESS_MSG)); // 显示同步进度信息
+            }
+        }
+    }
+
+    public boolean onOptionsItemSelected(MenuItem item) {
+        switch (item.getItemId()) {
+            case android.R.id.home:
+                Intent intent = new Intent(this, NotesListActivity.class); // 创建返回笔记列表的意图
+                intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); // 清除顶部活动
+                startActivity(intent); // 启动活动
+                return true; // 返回true表示事件已处理
+            default:
+                return false; // 返回false表示未处理事件
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/NotesProvider.java b/src/NotesProvider.java
new file mode 100644
index 0000000..c84269a
--- /dev/null
+++ b/src/NotesProvider.java
@@ -0,0 +1,303 @@
+/*
+ * 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; // 包声明
+
+import android.app.SearchManager; // 导入搜索管理器
+import android.content.ContentProvider; // 导入内容提供者
+import android.content.ContentUris; // 导入内容URI
+import android.content.ContentValues; // 导入内容值
+import android.content.Intent; // 导入意图
+import android.content.UriMatcher; // 导入URI匹配器
+import android.database.Cursor; // 导入游标
+import android.database.sqlite.SQLiteDatabase; // 导入SQLite数据库
+import android.net.Uri; // 导入URI
+import android.text.TextUtils; // 导入文本工具
+import android.util.Log; // 导入日志
+
+import net.micode.notes.R; // 导入资源
+import net.micode.notes.data.Notes.DataColumns; // 导入数据列
+import net.micode.notes.data.Notes.NoteColumns; // 导入笔记列
+import net.micode.notes.data.NotesDatabaseHelper.TABLE; // 导入数据库表
+
+// 笔记提供者类
+public class NotesProvider extends ContentProvider {
+    private static final UriMatcher mMatcher; // URI匹配器
+
+    private NotesDatabaseHelper mHelper; // 数据库助手
+
+    private static final String TAG = "NotesProvider"; // 日志标签
+
+    // URI常量
+    private static final int URI_NOTE = 1; // 笔记URI
+    private static final int URI_NOTE_ITEM = 2; // 单个笔记URI
+    private static final int URI_DATA = 3; // 数据URI
+    private static final int URI_DATA_ITEM = 4; // 单个数据URI
+
+    private static final int URI_SEARCH = 5; // 搜索URI
+    private static final int URI_SEARCH_SUGGEST = 6; // 搜索建议URI
+
+    // 静态代码块，初始化URI匹配器
+    static {
+        mMatcher = new UriMatcher(UriMatcher.NO_MATCH); // 创建URI匹配器
+        mMatcher.addURI(Notes.AUTHORITY, "note", URI_NOTE); // 添加笔记URI
+        mMatcher.addURI(Notes.AUTHORITY, "note/#", URI_NOTE_ITEM); // 添加单个笔记URI
+        mMatcher.addURI(Notes.AUTHORITY, "data", URI_DATA); // 添加数据URI
+        mMatcher.addURI(Notes.AUTHORITY, "data/#", URI_DATA_ITEM); // 添加单个数据URI
+        mMatcher.addURI(Notes.AUTHORITY, "search", URI_SEARCH); // 添加搜索URI
+        mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY, URI_SEARCH_SUGGEST); // 添加搜索建议URI
+        mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY + "/*", URI_SEARCH_SUGGEST); // 添加搜索建议URI
+    }
+
+    // 搜索投影常量
+    private static final String NOTES_SEARCH_PROJECTION = NoteColumns.ID + ","
+            + NoteColumns.ID + " AS " + SearchManager.SUGGEST_COLUMN_INTENT_EXTRA_DATA + ","
+            + "TRIM(REPLACE(" + NoteColumns.SNIPPET + ", x'0A','')) AS " + SearchManager.SUGGEST_COLUMN_TEXT_1 + ","
+            + "TRIM(REPLACE(" + NoteColumns.SNIPPET + ", x'0A','')) AS " + SearchManager.SUGGEST_COLUMN_TEXT_2 + ","
+            + 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; // 搜索结果投影
+
+    // 笔记片段搜索查询
+    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;
+
+    @Override
+    public boolean onCreate() {
+        mHelper = NotesDatabaseHelper.getInstance(getContext()); // 获取数据库助手实例
+        return true; // 返回创建成功
+    }
+
+    @Override
+    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
+                        String sortOrder) {
+        Cursor c = null; // 游标
+        SQLiteDatabase db = mHelper.getReadableDatabase(); // 获取可读数据库
+        String id = null; // ID
+        switch (mMatcher.match(uri)) { // 根据URI匹配
+            case URI_NOTE:
+                c = db.query(TABLE.NOTE, projection, selection, selectionArgs, null, null,
+                        sortOrder); // 查询笔记
+                break;
+            case URI_NOTE_ITEM:
+                id = uri.getPathSegments().get(1); // 获取笔记ID
+                c = db.query(TABLE.NOTE, projection, NoteColumns.ID + "=" + id
+                        + parseSelection(selection), selectionArgs, null, null, sortOrder); // 查询单个笔记
+                break;
+            case URI_DATA:
+                c = db.query(TABLE.DATA, projection, selection, selectionArgs, null, null,
+                        sortOrder); // 查询数据
+                break;
+            case URI_DATA_ITEM:
+                id = uri.getPathSegments().get(1); // 获取数据ID
+                c = db.query(TABLE.DATA, projection, DataColumns.ID + "=" + id
+                        + parseSelection(selection), selectionArgs, null, null, sortOrder); // 查询单个数据
+                break;
+            case URI_SEARCH:
+            case URI_SEARCH_SUGGEST:
+                // 对搜索和建议的特殊处理
+                if (sortOrder != null || projection != null) {
+                    throw new IllegalArgumentException(
+                            "do not specify sortOrder, selection, selectionArgs, or projection" + "with this query");
+                }
+
+                String searchString = null; // 搜索字符串
+                if (mMatcher.match(uri) == URI_SEARCH_SUGGEST) {
+                    if (uri.getPathSegments().size() > 1) {
+                        searchString = uri.getPathSegments().get(1); // 获取搜索字符串
+                    }
+                } else {
+                    searchString = uri.getQueryParameter("pattern"); // 获取查询参数
+                }
+
+                if (TextUtils.isEmpty(searchString)) {
+                    return null; // 如果搜索字符串为空，返回null
+                }
+
+                try {
+                    searchString = String.format("%%%s%%", searchString); // 格式化搜索字符串
+                    c = db.rawQuery(NOTES_SNIPPET_SEARCH_QUERY,
+                            new String[] { searchString }); // 执行原始查询
+                } catch (IllegalStateException ex) {
+                    Log.e(TAG, "got exception: " + ex.toString()); // 处理异常
+                }
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri); // 处理未知URI
+        }
+        if (c != null) {
+            c.setNotificationUri(getContext().getContentResolver(), uri); // 设置通知URI
+        }
+        return c; // 返回游标
+    }
+
+    @Override
+    public Uri insert(Uri uri, ContentValues values) {
+        SQLiteDatabase db = mHelper.getWritableDatabase(); // 获取可写数据库
+        long dataId = 0, noteId = 0, insertedId = 0; // 初始化ID
+        switch (mMatcher.match(uri)) { // 根据URI匹配
+            case URI_NOTE:
+                insertedId = noteId = db.insert(TABLE.NOTE, null, values); // 插入笔记
+                break;
+            case URI_DATA:
+                if (values.containsKey(DataColumns.NOTE_ID)) {
+                    noteId = values.getAsLong(DataColumns.NOTE_ID); // 获取笔记ID
+                } else {
+                    Log.d(TAG, "Wrong data format without note id:" + values.toString()); // 处理错误
+                }
+                insertedId = dataId = db.insert(TABLE.DATA, null, values); // 插入数据
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri); // 处理未知URI
+        }
+        // 通知笔记URI
+        if (noteId > 0) {
+            getContext().getContentResolver().notifyChange(
+                    ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null); // 通知更改
+        }
+
+        // 通知数据URI
+        if (dataId > 0) {
+            getContext().getContentResolver().notifyChange(
+                    ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId), null); // 通知更改
+        }
+
+        return ContentUris.withAppendedId(uri, insertedId); // 返回插入的URI
+    }
+
+    @Override
+    public int delete(Uri uri, String selection, String[] selectionArgs) {
+        int count = 0; // 删除计数
+        String id = null; // ID
+        SQLiteDatabase db = mHelper.getWritableDatabase(); // 获取可写数据库
+        boolean deleteData = false; // 是否删除数据
+        switch (mMatcher.match(uri)) { // 根据URI匹配
+            case URI_NOTE:
+                selection = "(" + selection + ") AND " + NoteColumns.ID + ">0 "; // 构造选择条件
+                count = db.delete(TABLE.NOTE, selection, selectionArgs); // 删除笔记
+                break;
+            case URI_NOTE_ITEM:
+                id = uri.getPathSegments().get(1); // 获取笔记ID
+                // ID小于0的系统文件夹不允许删除
+                long noteId = Long.valueOf(id); // 转换ID
+                if (noteId <= 0) {
+                    break; // 如果ID无效，跳过
+                }
+                count = db.delete(TABLE.NOTE,
+                        NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs); // 删除单个笔记
+                break;
+            case URI_DATA:
+                count = db.delete(TABLE.DATA, selection, selectionArgs); // 删除数据
+                deleteData = true; // 标记为删除数据
+                break;
+            case URI_DATA_ITEM:
+                id = uri.getPathSegments().get(1); // 获取数据ID
+                count = db.delete(TABLE.DATA,
+                        DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs); // 删除单个数据
+                deleteData = true; // 标记为删除数据
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri); // 处理未知URI
+        }
+        if (count > 0) {
+            if (deleteData) {
+                getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null); // 通知笔记URI更改
+            }
+            getContext().getContentResolver().notifyChange(uri, null); // 通知URI更改
+        }
+        return count; // 返回删除计数
+    }
+
+    @Override
+    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
+        int count = 0; // 更新计数
+        String id = null; // ID
+        SQLiteDatabase db = mHelper.getWritableDatabase(); // 获取可写数据库
+        boolean updateData = false; // 是否更新数据
+        switch (mMatcher.match(uri)) { // 根据URI匹配
+            case URI_NOTE:
+                increaseNoteVersion(-1, selection, selectionArgs); // 增加笔记版本
+                count = db.update(TABLE.NOTE, values, selection, selectionArgs); // 更新笔记
+                break;
+            case URI_NOTE_ITEM:
+                id = uri.getPathSegments().get(1); // 获取笔记ID
+                increaseNoteVersion(Long.valueOf(id), selection, selectionArgs); // 增加笔记版本
+                count = db.update(TABLE.NOTE, values, NoteColumns.ID + "=" + id
+                        + parseSelection(selection), selectionArgs); // 更新单个笔记
+                break;
+            case URI_DATA:
+                count = db.update(TABLE.DATA, values, selection, selectionArgs); // 更新数据
+                updateData = true; // 标记为更新数据
+                break;
+            case URI_DATA_ITEM:
+                id = uri.getPathSegments().get(1); // 获取数据ID
+                count = db.update(TABLE.DATA, values, DataColumns.ID + "=" + id
+                        + parseSelection(selection), selectionArgs); // 更新单个数据
+                updateData = true; // 标记为更新数据
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri); // 处理未知URI
+        }
+
+        if (count > 0) {
+            if (updateData) {
+                getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null); // 通知笔记URI更改
+            }
+            getContext().getContentResolver().notifyChange(uri, null); // 通知URI更改
+        }
+        return count; // 返回更新计数
+    }
+
+    // 解析选择条件
+    private String parseSelection(String selection) {
+        return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : ""); // 返回解析后的选择
+    }
+
+    // 增加笔记版本
+    private void increaseNoteVersion(long id, String selection, String[] selectionArgs) {
+        StringBuilder sql = new StringBuilder(120); // SQL构建器
+        sql.append("UPDATE "); // 更新语句
+        sql.append(TABLE.NOTE); // 指定表
+        sql.append(" SET ");
+        sql.append(NoteColumns.VERSION);
+        sql.append("=" + NoteColumns.VERSION + "+1 "); // 增加版本
+
+        if (id > 0 || !TextUtils.isEmpty(selection)) {
+            sql.append(" WHERE "); // 添加WHERE条件
+        }
+        if (id > 0) {
+            sql.append(NoteColumns.ID + "=" + String.valueOf(id)); // 指定ID
+        }
+        if (!TextUtils.isEmpty(selection)) {
+            String selectString = id > 0 ? parseSelection(selection) : selection; // 选择条件
+            for (String args : selectionArgs) {
+                selectString = selectString.replaceFirst("\\?", args); // 替换参数
+            }
+            sql.append(selectString); // 添加选择条件
+        }
+
+        mHelper.getWritableDatabase().execSQL(sql.toString()); // 执行SQL语句
+    }
+
+    @Override
+    public String getType(Uri uri) {
+        // TODO Auto-generated method stub
+        return null; // 返回null
+    }
+}
\ No newline at end of file