diff --git a/src/Contact.java b/src/Contact.java
new file mode 100644
index 0000000..b9b793b
--- /dev/null
+++ b/src/Contact.java
@@ -0,0 +1,87 @@
+/*
+ * 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.Context; // 导入Android上下文类，用于访问系统资源
+import android.database.Cursor; // 导入Android游标类，用于查询数据库
+import android.provider.ContactsContract.CommonDataKinds.Phone; // 导入Android联系人电话信息类
+import android.provider.ContactsContract.Data; // 导入Android联系人数据类
+import android.telephony.PhoneNumberUtils; // 导入Android电话号码工具类
+import android.util.Log; // 导入Android日志工具类
+
+import java.util.HashMap; // 导入Java哈希表类，用于缓存查询结果
+
+public class Contact {
+    // 静态的哈希表，用于缓存电话号码和对应的联系人姓名
+    private static HashMap<String, String> sContactCache;
+    // 日志标签，用于在日志中标识来自该类的消息
+    private static final String TAG = "Contact";
+
+    // SQL查询条件，用于查找与给定电话号码匹配的联系人信息
+    // 使用PHONE_NUMBERS_EQUAL函数比较电话号码，确保号码格式的一致性
+    // 限制数据类型为电话号码类型，并通过子查询确保电话号码的最小匹配字符为'+'
+    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 = '+')";
+
+    // 根据给定的电话号码获取联系人的姓名
+    public static String getContact(Context context, String phoneNumber) {
+        // 如果缓存为空，则初始化缓存
+        if(sContactCache == null) {
+            sContactCache = new HashMap<String, String>();
+        }
+
+        // 检查缓存中是否已有该电话号码对应的联系人姓名
+        if(sContactCache.containsKey(phoneNumber)) {
+            return sContactCache.get(phoneNumber); // 如果存在，则直接返回缓存中的姓名
+        }
+
+        // 构造SQL查询条件，将占位符"+"替换为电话号码的最小匹配字符
+        String selection = CALLER_ID_SELECTION.replace("+",
+                PhoneNumberUtils.toCallerIDMinMatch(phoneNumber));
+
+        // 执行数据库查询，获取与电话号码匹配的联系人姓名
+        Cursor cursor = context.getContentResolver().query(
+                Data.CONTENT_URI, // 查询联系人数据表
+                new String [] { Phone.DISPLAY_NAME }, // 需要查询的字段：联系人显示名称
+                selection, // 查询条件
+                new String[] { phoneNumber }, // 查询条件中的占位符参数
+                null); // 排序条件，这里为null表示不排序
+
+        // 检查查询结果是否为空且是否可以移动到第一行
+        if (cursor != null && cursor.moveToFirst()) {
+            try {
+                String name = cursor.getString(0); // 获取联系人显示名称
+                sContactCache.put(phoneNumber, name); // 将查询结果存入缓存
+                return name; // 返回联系人姓名
+            } catch (IndexOutOfBoundsException e) {
+                // 如果发生数组越界异常，记录错误日志并返回null
+                Log.e(TAG, " Cursor get string error " + e.toString());
+                return null;
+            } finally {
+                cursor.close(); // 关闭游标，释放资源
+            }
+        } else {
+            // 如果没有找到匹配的联系人，记录调试日志并返回null
+            Log.d(TAG, "No contact matched with number:" + phoneNumber);
+            return null;
+        }
+    }
+}
diff --git a/src/Notes.java b/src/Notes.java
new file mode 100644
index 0000000..2f2907e
--- /dev/null
+++ b/src/Notes.java
@@ -0,0 +1,298 @@
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * 你可以在不违反许可协议的情况下使用此文件。
+ * 你可以在以下地址获取许可证的副本：
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 除非适用法律要求或书面同意，软件
+ * 根据许可证分发是按“原样”基础进行的，
+ * 不附带任何明示或暗示的担保或条件。
+ * 请参阅许可证以获取特定语言的权限和
+ * 限制。
+ */
+
+package net.micode.notes.data;
+
+import android.net.Uri;
+
+// 定义了一个名为Notes的类，包含了与笔记应用相关的常量和接口
+public class Notes {
+    // 定义了Content Provider的权限字符串
+    public static final String AUTHORITY = "micode_notes";
+    // 定义了日志标签字符串
+    public static final String TAG = "Notes";
+
+    // 定义了笔记类型的常量
+    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是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 } 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
+     * {@link Notes#ID_TRASH_FOLER} 用于存储已删除的笔记
+     */
+    public static final int ID_ROOT_FOLDER = 0;
+    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;
+
+    // 定义了一些Intent的extra键名
+    public static final String INTENT_EXTRA_ALERT_DATE = "net.micode.notes.alert_date";  // 提醒日期
+    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
+
+    // 定义了小部件类型的常量
+    public static final int TYPE_WIDGET_INVALIDE = -1;  // 无效的小部件
+    public static final int TYPE_WIDGET_2X = 0;  // 2x尺寸的小部件
+    public static final int TYPE_WIDGET_4X = 1;  // 4x尺寸的小部件
+
+    // 定义一个内部类DataConstants，包含一些与数据类型相关的常量
+    public static class DataConstants {
+        // 定义了文本笔记的数据类型
+        public static final String NOTE = TextNote.CONTENT_ITEM_TYPE;
+        // 定义了通话笔记的数据类型
+        public static final String CALL_NOTE = CallNote.CONTENT_ITEM_TYPE;
+    }
+
+    /**
+     * Uri用于查询所有的笔记和文件夹
+     * 解析为：content://micode_notes/note
+     */
+    public static final Uri CONTENT_NOTE_URI = Uri.parse("content://" + AUTHORITY + "/note");
+
+    /**
+     * Uri用于查询数据
+     * 解析为：content://micode_notes/data
+     */
+    public static final Uri CONTENT_DATA_URI = Uri.parse("content://" + AUTHORITY + "/data");
+
+    // 定义了一个接口NoteColumns，包含了一些与笔记和文件夹相关的列名
+    public interface NoteColumns {
+        /**
+         * 笔记或文件夹的唯一ID
+         * <P> 类型：INTEGER (long) </P>
+         */
+        public static final String ID = "_id";
+
+        /**
+         * 笔记或文件夹的父ID
+         * <P> 类型：INTEGER (long) </P>
+         */
+        public static final String PARENT_ID = "parent_id";
+
+        /**
+         * 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";
+
+        /**
+         * 笔记或文件夹的最新修改日期
+         * <P> 类型：INTEGER (long) </P>
+         */
+        public static final String MODIFIED_DATE = "modified_date";
+
+        /**
+         * 笔记的提醒日期
+         * <P> 类型：INTEGER (long) </P>
+         */
+        public static final String ALERTED_DATE = "alert_date";
+
+        /**
+         * 文件夹的名称或笔记的文本内容
+         * <P> 类型：TEXT </P>
+         */
+        public static final String SNIPPET = "snippet";
+
+        /**
+         * 笔记的小部件ID
+         * <P> 类型：INTEGER (long) </P>
+         */
+        public static final String WIDGET_ID = "widget_id";
+
+        /**
+         * 笔记的小部件类型
+         * <P> 类型：INTEGER (long) </P>
+         */
+        public static final String WIDGET_TYPE = "widget_type";
+
+        /**
+         * 笔记的背景颜色ID
+         * <P> 类型：INTEGER (long) </P>
+         */
+        public static final String BG_COLOR_ID = "bg_color_id";
+
+        /**
+         * 对于文本笔记，它没有附件；对于多媒体笔记，至少有一个附件
+         * <P> 类型：INTEGER </P>
+         */
+        public static final String HAS_ATTACHMENT = "has_attachment";
+
+        /**
+         * 文件夹中的笔记数量
+         * <P> 类型：INTEGER (long) </P>
+         */
+        public static final String NOTES_COUNT = "notes_count";
+
+        /**
+         * 笔记或文件夹的类型
+         * <P> 类型：INTEGER </P>
+         */
+        public static final String TYPE = "type";
+
+        /**
+         * 最后同步ID
+         * <P> 类型：INTEGER (long) </P>
+         */
+        public static final String SYNC_ID = "sync_id";
+
+        /**
+         * 标志以指示是否本地修改过
+         * <P> 类型：INTEGER </P>
+         */
+        public static final String LOCAL_MODIFIED = "local_modified";
+
+        /**
+         * 移动到临时文件夹之前的原始父ID
+         * <P> 类型：INTEGER </P>
+         */
+        public static final String ORIGIN_PARENT_ID = "origin_parent_id";
+
+        /**
+         * Google任务ID
+         * <P> 类型：TEXT </P>
+         */
+        public static final String GTASK_ID = "gtask_id";
+
+        /**
+         * 版本号
+         * <P> 类型：INTEGER (long) </P>
+         */
+        public static final String VERSION = "version";
+    }
+
+    // 定义了一个接口DataColumns，包含了一些与数据相关的列名
+    public interface DataColumns {
+        /**
+         * 数据的唯一ID
+         * <P> 类型：INTEGER (long) </P>
+         */
+        public static final String ID = "_id";
+
+        /**
+         * 此行所代表项目的数据类型（MIME类型）。
+         * <P> 类型：TEXT </P>
+         */
+        public static final String MIME_TYPE = "mime_type";
+
+        /**
+         * 引用此数据属于的笔记ID
+         * <P> 类型：INTEGER (long) </P>
+         */
+        public static final String NOTE_ID = "note_id";
+
+        /**
+         * 数据的创建日期
+         * <P> 类型：INTEGER (long) </P>
+         */
+        public static final String CREATED_DATE = "created_date";
+
+        /**
+         * 数据的最新修改日期
+         * <P> 类型：INTEGER (long) </P>
+         */
+        public static final String MODIFIED_DATE = "modified_date";
+
+        /**
+         * 数据的内容
+         * <P> 类型：TEXT </P>
+         */
+        public static final String CONTENT = "content";
+
+        /**
+         * 通用数据列，含义取决于 {@link #MIME_TYPE}，用于整型数据类型
+         * <P> 类型：INTEGER </P>
+         */
+        public static final String DATA1 = "data1";
+
+        /**
+         * 通用数据列，含义取决于 {@link #MIME_TYPE}，用于整型数据类型
+         * <P> 类型：INTEGER </P>
+         */
+        public static final String DATA2 = "data2";
+
+        /**
+         * 通用数据列，含义取决于 {@link #MIME_TYPE}，用于文本数据类型
+         * <P> 类型：TEXT </P>
+         */
+        public static final String DATA3 = "data3";
+
+        /**
+         * 通用数据列，含义取决于 {@link #MIME_TYPE}，用于文本数据类型
+         * <P> 类型：TEXT </P>
+         */
+        public static final String DATA4 = "data4";
+
+        /**
+         * 通用数据列，含义取决于 {@link #MIME_TYPE}，用于文本数据类型
+         * <P> 类型：TEXT </P>
+         */
+        public static final String DATA5 = "data5";
+    }
+
+    // 定义了一个内部类TextNote，继承自DataColumns，表示文本笔记的数据结构
+    public static final class TextNote implements DataColumns {
+        /**
+         * 模式以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;
+
+        // 定义了文本笔记模式的常量
+        public static final int MODE_CHECK_LIST = 1;
+
+        // 定义了文本笔记的MIME类型
+        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";
+
+        /**
+         * 文本笔记的Uri
+         * 解析为：content://micode_notes/text_note
+         */
+        public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY + "/text_note");
+    }
+
+    // 定义了一个内部类CallNote，继承自DataColumns，表示通话笔记的数据结构
+    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;
+
+        /**
+         * 此记录的电话号码
+         * <P> 类型：TEXT </P>
+         */
+        public static final String PHONE_NUMBER = DATA3;
+
+        // 定义了通话笔记的MIME类型
+        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";
+
+        /**
+         * 通话笔记的Uri
+         * 解析为：content://micode_notes/call_note
+         */
+        public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY + "/call_note");
+    }
+}
diff --git a/src/NotesDatabaseHelper.java b/src/NotesDatabaseHelper.java
new file mode 100644
index 0000000..3674cb6
--- /dev/null
+++ b/src/NotesDatabaseHelper.java
@@ -0,0 +1,389 @@
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * 你可以在不违反许可协议的情况下使用此文件。
+ * 你可以在以下地址获取许可证的副本：
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 除非适用法律要求或书面同意，软件
+ * 根据许可证分发是按“原样”基础进行的，
+ * 不附带任何明示或暗示的担保或条件。
+ * 请参阅许可证以获取特定语言的权限和
+ * 限制。
+ */
+
+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 是一个 SQLiteOpenHelper 类的子类，用于管理笔记应用的数据库
+public class NotesDatabaseHelper extends SQLiteOpenHelper {
+    // 定义了数据库名称
+    private static final String DB_NAME = "note.db";
+
+    // 定义了数据库版本号
+    private static final int DB_VERSION = 4;
+
+    // 定义了一个内部接口TABLE，包含了表名常量
+    public interface TABLE {
+        public static final String NOTE = "note";  // 笔记表名
+        public static final String DATA = "data";  // 数据表名
+    }
+
+    // 定义了日志标签字符串
+    private static final String TAG = "NotesDatabaseHelper";
+
+    // 定义了单例实例
+    private static NotesDatabaseHelper mInstance;
+
+    // 定义了创建笔记表的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" +
+        ")";
+
+    // 定义了创建 DATA 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 ''" +
+        ")";
+
+    // 定义了创建数据表中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 + "); ";
+
+    /**
+     * 当笔记移动到文件夹时，增加文件夹的笔记数量
+     */
+    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";
+
+    /**
+     * 当笔记从文件夹中移除时，减少文件夹的笔记数量
+     */
+    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";
+
+    /**
+     * 当向文件夹中插入新笔记时，增加文件夹的笔记数量
+     */
+    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";
+
+    /**
+     * 当从文件夹中删除笔记时，减少文件夹的笔记数量
+     */
+    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";
+
+    /**
+     * 当插入类型为 {@link DataConstants#NOTE} 的数据时，更新笔记的内容
+     */
+    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";
+
+    /**
+     * 当更新类型为 {@link DataConstants#NOTE} 的数据时，更新笔记的内容
+     */
+    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";
+
+    /**
+     * 当删除类型为 {@link DataConstants#NOTE} 的数据时，清空笔记的内容
+     */
+    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";
+
+    /**
+     * 当删除笔记时，删除属于该笔记的所有数据
+     */
+    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";
+
+    /**
+     * 当删除文件夹时，删除属于该文件夹的所有笔记
+     */
+    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";
+
+    /**
+     * 当文件夹被移动到回收站文件夹时，将文件夹中的所有笔记也移动到回收站文件夹
+     */
+    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，初始化数据库帮助器
+    public NotesDatabaseHelper(Context context) {
+        super(context, DB_NAME, null, DB_VERSION);
+    }
+
+    // 创建笔记表的方法
+    public void createNoteTable(SQLiteDatabase db) {
+        db.execSQL(CREATE_NOTE_TABLE_SQL);
+        reCreateNoteTableTriggers(db);
+        createSystemFolder(db);
+        Log.d(TAG, "note table has been created");
+    }
+
+    // 重新创建笔记表触发器的方法
+    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");
+        db.execSQL("DROP TRIGGER IF EXISTS decrease_folder_count_on_delete");
+        db.execSQL("DROP TRIGGER IF EXISTS delete_data_on_delete");
+        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);
+        db.execSQL(NOTE_DELETE_DATA_ON_DELETE_TRIGGER);
+        db.execSQL(NOTE_INCREASE_FOLDER_COUNT_ON_INSERT_TRIGGER);
+        db.execSQL(FOLDER_DELETE_NOTES_ON_DELETE_TRIGGER);
+        db.execSQL(FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER);
+    }
+
+    // 创建系统文件夹的方法
+    private void createSystemFolder(SQLiteDatabase db) {
+        ContentValues values = new ContentValues();
+
+        /**
+         * 创建通话记录文件夹，用于存储通话笔记
+         */
+        values.put(NoteColumns.ID, Notes.ID_CALL_RECORD_FOLDER);
+        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
+        db.insert(TABLE.NOTE, null, values);
+
+        /**
+         * 创建根文件夹，默认文件夹
+         */
+        values.clear();
+        values.put(NoteColumns.ID, Notes.ID_ROOT_FOLDER);
+        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
+        db.insert(TABLE.NOTE, null, values);
+
+        /**
+         * 创建临时文件夹，用于移动笔记
+         */
+        values.clear();
+        values.put(NoteColumns.ID, Notes.ID_TEMPARAY_FOLDER);
+        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
+        db.insert(TABLE.NOTE, null, values);
+
+        /**
+         * 创建回收站文件夹
+         */
+        values.clear();
+        values.put(NoteColumns.ID, Notes.ID_TRASH_FOLER);
+        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
+        db.insert(TABLE.NOTE, null, values);
+    }
+
+    // 创建数据表的方法
+    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");
+    }
+
+    // 重新创建数据表触发器的方法
+    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 单例实例的方法
+    static synchronized NotesDatabaseHelper getInstance(Context context) {
+        if (mInstance == null) {
+            mInstance = new NotesDatabaseHelper(context);
+        }
+        return mInstance;
+    }
+
+    // 当数据库第一次创建时调用的方法
+    @Override
+    public void onCreate(SQLiteDatabase db) {
+        createNoteTable(db);
+        createDataTable(db);
+    }
+
+    // 当数据库需要升级时调用的方法
+    @Override
+    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
+        boolean reCreateTriggers = false;
+        boolean skipV2 = false;
+
+        // 如果当前版本是1，直接删除旧表并创建新表
+        if (oldVersion == 1) {
+            upgradeToV2(db);
+            skipV2 = true; // 这次升级包含了从v2到v3的升级
+            oldVersion++;
+        }
+
+        // 如果当前版本是2，添加新的列并创建系统文件夹
+        if (oldVersion == 2 && !skipV2) {
+            upgradeToV3(db);
+            reCreateTriggers = true;
+            oldVersion++;
+        }
+
+        // 如果当前版本是3，添加版本号列
+        if (oldVersion == 3) {
+            upgradeToV4(db);
+            oldVersion++;
+        }
+
+        // 如果需要重新创建触发器，调用相应的方法
+        if (reCreateTriggers) {
+            reCreateNoteTableTriggers(db);
+            reCreateDataTableTriggers(db);
+        }
+
+        // 如果升级失败，抛出异常
+        if (oldVersion != newVersion) {
+            throw new IllegalStateException("Upgrade notes database to version " + newVersion
+                    + " fails");
+        }
+    }
+
+    // 升级到数据库版本2的方法
+    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);
+    }
+
+    // 升级到数据库版本3的方法
+    private void upgradeToV3(SQLiteDatabase db) {
+        // 删除不再使用的触发器
+        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();
+        values.put(NoteColumns.ID, Notes.ID_TRASH_FOLER);
+        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
+        db.insert(TABLE.NOTE, null, values);
+    }
+
+    // 升级到数据库版本4的方法
+    private void upgradeToV4(SQLiteDatabase db) {
+        // 添加版本号列
+        db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.VERSION
+                + " INTEGER NOT NULL DEFAULT 0");
+    }
+}
diff --git a/src/NotesProvider.java b/src/NotesProvider.java
new file mode 100644
index 0000000..2cd497c
--- /dev/null
+++ b/src/NotesProvider.java
@@ -0,0 +1,342 @@
+/*
+ * 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.app.SearchManager;
+import android.content.ContentProvider;
+import android.content.ContentUris;
+import android.content.ContentValues;
+import android.content.Intent;
+import android.content.UriMatcher;
+import android.database.Cursor;
+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;
+
+public class NotesProvider extends ContentProvider {
+    // UriMatcher用于匹配不同的URI请求，返回相应的请求类型
+    private static final UriMatcher mMatcher;
+
+    // 数据库辅助类，用于创建和管理数据库
+    private NotesDatabaseHelper mHelper;
+
+    // 日志标签，便于调试和日志记录
+    private static final String TAG = "NotesProvider";
+
+    // 定义URI请求类型常量
+    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;
+
+    // 静态代码块，在类加载时初始化UriMatcher
+    static {
+        mMatcher = new UriMatcher(UriMatcher.NO_MATCH);
+        mMatcher.addURI(Notes.AUTHORITY, "note", URI_NOTE);
+        mMatcher.addURI(Notes.AUTHORITY, "note/#", URI_NOTE_ITEM);
+        mMatcher.addURI(Notes.AUTHORITY, "data", URI_DATA);
+        mMatcher.addURI(Notes.AUTHORITY, "data/#", URI_DATA_ITEM);
+        mMatcher.addURI(Notes.AUTHORITY, "search", URI_SEARCH);
+        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'表示在sqlite中的'\n'字符。对于搜索结果中的标题和内容，
+     * 我们将修剪'\n'和空白字符，以便显示更多信息。
+     */
+    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;
+
+    // SQL查询语句，用于根据搜索字符串查询笔记片段
+    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;
+
+    // 创建ContentProvider时调用，初始化NotesDatabaseHelper
+    @Override
+    public boolean onCreate() {
+        mHelper = NotesDatabaseHelper.getInstance(getContext());
+        return true;
+    }
+
+    // 根据不同的URI请求类型执行查询操作
+    @Override
+    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
+            String sortOrder) {
+        Cursor c = null;
+        SQLiteDatabase db = mHelper.getReadableDatabase();
+        String id = null;
+        switch (mMatcher.match(uri)) {
+            case URI_NOTE:
+                // 查询所有笔记
+                c = db.query(TABLE.NOTE, projection, selection, selectionArgs, null, null,
+                        sortOrder);
+                break;
+            case URI_NOTE_ITEM:
+                // 查询特定ID的笔记
+                id = uri.getPathSegments().get(1);
+                c = db.query(TABLE.NOTE, projection, NoteColumns.ID + "=" + id
+                        + parseSelection(selection), selectionArgs, null, null, sortOrder);
+                break;
+            case URI_DATA:
+                // 查询所有笔记数据
+                c = db.query(TABLE.DATA, projection, selection, selectionArgs, null, null,
+                        sortOrder);
+                break;
+            case URI_DATA_ITEM:
+                // 查询特定ID的笔记数据
+                id = uri.getPathSegments().get(1);
+                c = db.query(TABLE.DATA, projection, DataColumns.ID + "=" + id
+                        + parseSelection(selection), selectionArgs, null, null, sortOrder);
+                break;
+            case URI_SEARCH:
+            case URI_SEARCH_SUGGEST:
+                // 搜索时不允许指定排序条件、选择条件、选择参数或投影
+                if (sortOrder != null || projection != null) {
+                    throw new IllegalArgumentException(
+                            "不允许在搜索时指定排序条件、选择条件、选择参数或投影");
+                }
+
+                String searchString = null;
+                // 获取搜索字符串
+                if (mMatcher.match(uri) == URI_SEARCH_SUGGEST) {
+                    if (uri.getPathSegments().size() > 1) {
+                        searchString = uri.getPathSegments().get(1);
+                    }
+                } else {
+                    searchString = uri.getQueryParameter("pattern");
+                }
+
+                // 如果搜索字符串为空，返回null
+                if (TextUtils.isEmpty(searchString)) {
+                    return null;
+                }
+
+                try {
+                    // 格式化搜索字符串，使其可以用于LIKE查询
+                    searchString = String.format("%%%s%%", searchString);
+                    // 执行搜索查询
+                    c = db.rawQuery(NOTES_SNIPPET_SEARCH_QUERY,
+                            new String[] { searchString });
+                } catch (IllegalStateException ex) {
+                    Log.e(TAG, "发生异常: " + ex.toString());
+                }
+                break;
+            default:
+                // 如果URI请求类型未知，抛出异常
+                throw new IllegalArgumentException("未知的URI " + uri);
+        }
+        // 设置游标的通知URI，以便内容变化时通知监听者
+        if (c != null) {
+            c.setNotificationUri(getContext().getContentResolver(), uri);
+        }
+        return c;
+    }
+
+    // 根据不同的URI请求类型插入数据
+    @Override
+    public Uri insert(Uri uri, ContentValues values) {
+        SQLiteDatabase db = mHelper.getWritableDatabase();
+        long dataId = 0, noteId = 0, insertedId = 0;
+        switch (mMatcher.match(uri)) {
+            case URI_NOTE:
+                // 插入新的笔记
+                insertedId = noteId = db.insert(TABLE.NOTE, null, values);
+                break;
+            case URI_DATA:
+                // 插入新的笔记数据
+                if (values.containsKey(DataColumns.NOTE_ID)) {
+                    noteId = values.getAsLong(DataColumns.NOTE_ID);
+                } else {
+                    Log.d(TAG, "数据格式错误，缺少笔记ID:" + values.toString());
+                }
+                insertedId = dataId = db.insert(TABLE.DATA, null, values);
+                break;
+            default:
+                // 如果URI请求类型未知，抛出异常
+                throw new IllegalArgumentException("未知的URI " + uri);
+        }
+        // 通知笔记URI变化
+        if (noteId > 0) {
+            getContext().getContentResolver().notifyChange(
+                    ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null);
+        }
+
+        // 通知数据URI变化
+        if (dataId > 0) {
+            getContext().getContentResolver().notifyChange(
+                    ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId), null);
+        }
+
+        return ContentUris.withAppendedId(uri, insertedId);
+    }
+
+    // 根据不同的URI请求类型删除数据
+    @Override
+    public int delete(Uri uri, String selection, String[] selectionArgs) {
+        int count = 0;
+        String id = null;
+        SQLiteDatabase db = mHelper.getWritableDatabase();
+        boolean deleteData = false;
+        switch (mMatcher.match(uri)) {
+            case URI_NOTE:
+                // 删除笔记时，确保ID大于0
+                selection = "(" + selection + ") AND " + NoteColumns.ID + ">0 ";
+                count = db.delete(TABLE.NOTE, selection, selectionArgs);
+                break;
+            case URI_NOTE_ITEM:
+                id = uri.getPathSegments().get(1);
+                long noteId = Long.valueOf(id);
+                // ID小于等于0的笔记为系统文件夹，不允许删除
+                if (noteId <= 0) {
+                    break;
+                }
+                // 删除特定ID的笔记
+                count = db.delete(TABLE.NOTE,
+                        NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
+                break;
+            case URI_DATA:
+                // 删除笔记数据
+                count = db.delete(TABLE.DATA, selection, selectionArgs);
+                deleteData = true;
+                break;
+            case URI_DATA_ITEM:
+                id = uri.getPathSegments().get(1);
+                // 删除特定ID的笔记数据
+                count = db.delete(TABLE.DATA,
+                        DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
+                deleteData = true;
+                break;
+            default:
+                // 如果URI请求类型未知，抛出异常
+                throw new IllegalArgumentException("未知的URI " + uri);
+        }
+        // 如果有数据被删除，通知URI变化
+        if (count > 0) {
+            if (deleteData) {
+                getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
+            }
+            getContext().getContentResolver().notifyChange(uri, null);
+        }
+        return count;
+    }
+
+    // 根据不同的URI请求类型更新数据
+    @Override
+    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
+        int count = 0;
+        String id = null;
+        SQLiteDatabase db = mHelper.getWritableDatabase();
+        boolean updateData = false;
+        switch (mMatcher.match(uri)) {
+            case URI_NOTE:
+                // 更新笔记时，增加笔记版本号
+                increaseNoteVersion(-1, selection, selectionArgs);
+                count = db.update(TABLE.NOTE, values, selection, selectionArgs);
+                break;
+            case URI_NOTE_ITEM:
+                id = uri.getPathSegments().get(1);
+                long noteId = Long.valueOf(id);
+                // 更新特定ID的笔记，并增加笔记版本号
+                increaseNoteVersion(noteId, selection, selectionArgs);
+                count = db.update(TABLE.NOTE, values, NoteColumns.ID + "=" + id
+                        + parseSelection(selection), selectionArgs);
+                break;
+            case URI_DATA:
+                // 更新笔记数据
+                count = db.update(TABLE.DATA, values, selection, selectionArgs);
+                updateData = true;
+                break;
+            case URI_DATA_ITEM:
+                id = uri.getPathSegments().get(1);
+                // 更新特定ID的笔记数据
+                count = db.update(TABLE.DATA, values, DataColumns.ID + "=" + id
+                        + parseSelection(selection), selectionArgs);
+                updateData = true;
+                break;
+            default:
+                // 如果URI请求类型未知，抛出异常
+                throw new IllegalArgumentException("未知的URI " + uri);
+        }
+
+        // 如果有数据被更新，通知URI变化
+        if (count > 0) {
+            if (updateData) {
+                getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
+            }
+            getContext().getContentResolver().notifyChange(uri, null);
+        }
+        return count;
+    }
+
+    // 解析选择条件字符串，如果存在选择条件，则添加到SQL查询中
+    private String parseSelection(String selection) {
+        return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : "");
+    }
+
+    // 增加笔记版本号
+    private void increaseNoteVersion(long id, String selection, String[] selectionArgs) {
+        StringBuilder sql = new StringBuilder(120);
+        sql.append("UPDATE ");
+        sql.append(TABLE.NOTE);
+        sql.append(" SET ");
+        sql.append(NoteColumns.VERSION);
+        sql.append("=" + NoteColumns.VERSION + "+1 ");
+
+        // 构建WHERE子句
+        if (id > 0 || !TextUtils.isEmpty(selection)) {
+            sql.append(" WHERE ");
+        }
+        if (id > 0) {
+            sql.append(NoteColumns.ID + "=" + String.valueOf(id));
+        }
+        if (!TextUtils.isEmpty(selection)) {
+            String selectString = id > 0 ? parseSelection(selection) : selection;
+            for (String args : selectionArgs) {
+                selectString = selectString.replaceFirst("\\?", args);
+            }
+            sql.append(selectString);
+        }
+
+        // 执行更新操作
+        mHelper.getWritableDatabase().execSQL(sql.toString());
+    }
+
+    // 返回URI对应的数据类型，这里未实现，返回null
+    @Override
+    public String getType(Uri uri) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+}
diff --git a/src/net/micode/notes/tool/BackupUtils.java b/src/net/micode/notes/tool/BackupUtils.java
index 39f6ec4..fdf8ece 100644
--- a/src/net/micode/notes/tool/BackupUtils.java
+++ b/src/net/micode/notes/tool/BackupUtils.java
@@ -36,56 +36,59 @@ import java.io.IOException;
 import java.io.PrintStream;
 
 
+好的，我将为`BackupUtils.java`文件中的每个语句提供更细致的注释：
+
+```java
 public class BackupUtils {
-    private static final String TAG = "BackupUtils";
-    // Singleton stuff
-    private static BackupUtils sInstance;
+    private static final String TAG = "BackupUtils"; // 定义日志标签，用于识别日志输出的来源
+
+    private static BackupUtils sInstance; // 声明一个静态实例变量，用于实现单例模式
 
+    // 提供一个公共的静态方法，用于获取BackupUtils的单例实例
     public static synchronized BackupUtils getInstance(Context context) {
         if (sInstance == null) {
-            sInstance = new BackupUtils(context);
+            sInstance = new BackupUtils(context); // 如果实例不存在，则新建一个实例
         }
-        return sInstance;
+        return sInstance; // 返回单例实例
     }
 
-    /**
-     * Following states are signs to represents backup or restore
-     * status
-     */
-    // Currently, the sdcard is not mounted
-    public static final int STATE_SD_CARD_UNMOUONTED           = 0;
-    // The backup file not exist
-    public static final int STATE_BACKUP_FILE_NOT_EXIST        = 1;
-    // The data is not well formated, may be changed by other programs
-    public static final int STATE_DATA_DESTROIED               = 2;
-    // Some run-time exception which causes restore or backup fails
-    public static final int STATE_SYSTEM_ERROR                 = 3;
-    // Backup or restore success
-    public static final int STATE_SUCCESS                      = 4;
+    // 定义一系列状态码，用于表示备份或恢复的状态
+    public static final int STATE_SD_CARD_UNMOUONTED = 0; // SD卡未挂载
+    public static final int STATE_BACKUP_FILE_NOT_EXIST = 1; // 备份文件不存在
+    public static final int STATE_DATA_DESTROIED = 2; // 数据格式不正确，可能被其他程序更改
+    public static final int STATE_SYSTEM_ERROR = 3; // 系统错误，导致备份或恢复失败
+    public static final int STATE_SUCCESS = 4; // 备份或恢复成功
 
-    private TextExport mTextExport;
+    private TextExport mTextExport; // TextExport对象，用于将数据导出到文本
 
+    // BackupUtils的私有构造函数，传入Context对象
     private BackupUtils(Context context) {
-        mTextExport = new TextExport(context);
+        mTextExport = new TextExport(context); // 初始化TextExport对象
     }
 
+    // 检查外部存储（SD卡）是否可用
     private static boolean externalStorageAvailable() {
-        return Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState());
+        return Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState()); // 比较存储状态是否为已挂载
     }
 
+    // 导出数据到文本文件，并返回操作结果状态码
     public int exportToText() {
-        return mTextExport.exportToText();
+        return mTextExport.exportToText(); // 调用TextExport对象的exportToText方法
     }
 
+    // 获取导出文本文件的文件名
     public String getExportedTextFileName() {
-        return mTextExport.mFileName;
+        return mTextExport.mFileName; // 返回TextExport对象中保存的文件名
     }
 
+    // 获取导出文本文件的目录路径
     public String getExportedTextFileDir() {
-        return mTextExport.mFileDirectory;
+        return mTextExport.mFileDirectory; // 返回TextExport对象中保存的文件目录
     }
 
+    // 内部类TextExport，封装了将笔记数据导出到文本文件的逻辑
     private static class TextExport {
+        // 定义查询笔记信息时需要的字段
         private static final String[] NOTE_PROJECTION = {
                 NoteColumns.ID,
                 NoteColumns.MODIFIED_DATE,
@@ -93,12 +96,12 @@ public class BackupUtils {
                 NoteColumns.TYPE
         };
 
+        // 定义NOTE_PROJECTION数组中各个字段的索引
         private static final int NOTE_COLUMN_ID = 0;
-
         private static final int NOTE_COLUMN_MODIFIED_DATE = 1;
-
         private static final int NOTE_COLUMN_SNIPPET = 2;
 
+        // 定义查询笔记数据时需要的字段
         private static final String[] DATA_PROJECTION = {
                 DataColumns.CONTENT,
                 DataColumns.MIME_TYPE,
@@ -108,93 +111,88 @@ public class BackupUtils {
                 DataColumns.DATA4,
         };
 
+        // 定义DATA_PROJECTION数组中各个字段的索引
         private static final int DATA_COLUMN_CONTENT = 0;
-
         private static final int DATA_COLUMN_MIME_TYPE = 1;
-
         private static final int DATA_COLUMN_CALL_DATE = 2;
-
         private static final int DATA_COLUMN_PHONE_NUMBER = 4;
 
-        private final String [] TEXT_FORMAT;
-        private static final int FORMAT_FOLDER_NAME          = 0;
-        private static final int FORMAT_NOTE_DATE            = 1;
-        private static final int FORMAT_NOTE_CONTENT         = 2;
+        // 用于格式化导出文本的字符串数组
+        private final String[] TEXT_FORMAT;
+        // 定义格式化字符串数组中的索引
+        private static final int FORMAT_FOLDER_NAME = 0;
+        private static final int FORMAT_NOTE_DATE = 1;
+        private static final int FORMAT_NOTE_CONTENT = 2;
 
-        private Context mContext;
-        private String mFileName;
-        private String mFileDirectory;
+        private Context mContext; // 应用程序上下文
+        private String mFileName; // 导出文本文件的文件名
+        private String mFileDirectory; // 导出文本文件的目录
 
+        // TextExport类的构造函数，初始化上下文和格式化字符串数组
         public TextExport(Context context) {
-            TEXT_FORMAT = context.getResources().getStringArray(R.array.format_for_exported_note);
-            mContext = context;
-            mFileName = "";
-            mFileDirectory = "";
+            TEXT_FORMAT = context.getResources().getStringArray(R.array.format_for_exported_note); // 从资源文件中获取格式化字符串数组
+            mContext = context; // 保存上下文对象
+            mFileName = ""; // 初始化文件名为空字符串
+            mFileDirectory = ""; // 初始化文件目录为空字符串
         }
 
+        // 根据索引获取格式化字符串
         private String getFormat(int id) {
-            return TEXT_FORMAT[id];
+            return TEXT_FORMAT[id]; // 返回格式化字符串数组中指定索引的字符串
         }
 
-        /**
-         * Export the folder identified by folder id to text
-         */
+        // 导出指定文件夹ID的笔记到文本
         private void exportFolderToText(String folderId, PrintStream ps) {
-            // Query notes belong to this folder
+            // 查询属于该文件夹的笔记
             Cursor notesCursor = mContext.getContentResolver().query(Notes.CONTENT_NOTE_URI,
                     NOTE_PROJECTION, NoteColumns.PARENT_ID + "=?", new String[] {
                         folderId
                     }, null);
-
             if (notesCursor != null) {
                 if (notesCursor.moveToFirst()) {
                     do {
-                        // Print note's last modified date
+                        // 打印笔记的最后修改日期
                         ps.println(String.format(getFormat(FORMAT_NOTE_DATE), DateFormat.format(
                                 mContext.getString(R.string.format_datetime_mdhm),
                                 notesCursor.getLong(NOTE_COLUMN_MODIFIED_DATE))));
-                        // Query data belong to this note
+                        // 查询属于该笔记的数据
                         String noteId = notesCursor.getString(NOTE_COLUMN_ID);
                         exportNoteToText(noteId, ps);
                     } while (notesCursor.moveToNext());
                 }
-                notesCursor.close();
+                notesCursor.close(); // 关闭游标
             }
         }
 
-        /**
-         * Export note identified by id to a print stream
-         */
+        // 导出指定ID的笔记到文本
         private void exportNoteToText(String noteId, PrintStream ps) {
+            // 查询笔记数据
             Cursor dataCursor = mContext.getContentResolver().query(Notes.CONTENT_DATA_URI,
                     DATA_PROJECTION, DataColumns.NOTE_ID + "=?", new String[] {
                         noteId
                     }, null);
-
             if (dataCursor != null) {
                 if (dataCursor.moveToFirst()) {
                     do {
                         String mimeType = dataCursor.getString(DATA_COLUMN_MIME_TYPE);
                         if (DataConstants.CALL_NOTE.equals(mimeType)) {
-                            // Print phone number
+                            // 如果MIME类型为通话笔记，则打印电话号码、通话日期和位置
                             String phoneNumber = dataCursor.getString(DATA_COLUMN_PHONE_NUMBER);
                             long callDate = dataCursor.getLong(DATA_COLUMN_CALL_DATE);
                             String location = dataCursor.getString(DATA_COLUMN_CONTENT);
-
                             if (!TextUtils.isEmpty(phoneNumber)) {
                                 ps.println(String.format(getFormat(FORMAT_NOTE_CONTENT),
                                         phoneNumber));
                             }
-                            // Print call date
                             ps.println(String.format(getFormat(FORMAT_NOTE_CONTENT), DateFormat
                                     .format(mContext.getString(R.string.format_datetime_mdhm),
                                             callDate)));
-                            // Print call attachment location
                             if (!TextUtils.isEmpty(location)) {
                                 ps.println(String.format(getFormat(FORMAT_NOTE_CONTENT),
                                         location));
                             }
                         } else if (DataConstants.NOTE.equals(mimeType)) {
+                            // 如果MIME类型为普通笔记，则打印笔记内容
                             String content = dataCursor.getString(DATA_COLUMN_CONTENT);
                             if (!TextUtils.isEmpty(content)) {
                                 ps.println(String.format(getFormat(FORMAT_NOTE_CONTENT),
@@ -203,9 +201,9 @@ public class BackupUtils {
                         }
                     } while (dataCursor.moveToNext());
                 }
-                dataCursor.close();
+                dataCursor.close(); // 关闭游标
             }
-            // print a line separator between note
+            // 打印笔记之间的分隔符
             try {
                 ps.write(new byte[] {
                         Character.LINE_SEPARATOR, Character.LETTER_NUMBER
@@ -215,130 +213,37 @@ public class BackupUtils {
             }
         }
 
-        /**
-         * Note will be exported as text which is user readable
-         */
+        // 执行导出操作，将笔记数据导出为用户可读的文本格式
         public int exportToText() {
             if (!externalStorageAvailable()) {
-                Log.d(TAG, "Media was not mounted");
+                Log.d(TAG, "Media was not mounted"); // 如果SD卡未挂载，则记录日志并返回状态码
                 return STATE_SD_CARD_UNMOUONTED;
             }
-
-            PrintStream ps = getExportToTextPrintStream();
+            PrintStream ps = getExportToTextPrintStream(); // 获取指向导出文本文件的PrintStream对象
             if (ps == null) {
-                Log.e(TAG, "get print stream error");
+                Log.e(TAG, "get print stream error"); // 如果获取PrintStream失败，则记录日志并返回状态码
                 return STATE_SYSTEM_ERROR;
             }
-            // First export folder and its notes
+            // 查询所有文件夹和其笔记，除了垃圾箱文件夹和通话记录文件夹
             Cursor folderCursor = mContext.getContentResolver().query(
                     Notes.CONTENT_NOTE_URI,
                     NOTE_PROJECTION,
                     "(" + NoteColumns.TYPE + "=" + Notes.TYPE_FOLDER + " AND "
                             + NoteColumns.PARENT_ID + "<>" + Notes.ID_TRASH_FOLER + ") OR "
                             + NoteColumns.ID + "=" + Notes.ID_CALL_RECORD_FOLDER, null, null);
-
             if (folderCursor != null) {
                 if (folderCursor.moveToFirst()) {
                     do {
-                        // Print folder's name
+                        // 打印文件夹名称
                         String folderName = "";
                         if(folderCursor.getLong(NOTE_COLUMN_ID) == Notes.ID_CALL_RECORD_FOLDER) {
-                            folderName = mContext.getString(R.string.call_record_folder_name);
+                            folderName = mContext.getString(R.string.call_record_folder_name); // 如果是通话记录文件夹，则使用资源文件中的名称
                         } else {
-                            folderName = folderCursor.getString(NOTE_COLUMN_SNIPPET);
+                            folderName = folderCursor.getString(NOTE_COLUMN_SNIPPET); // 否则，使用查询到的文件夹名称
                         }
                         if (!TextUtils.isEmpty(folderName)) {
                             ps.println(String.format(getFormat(FORMAT_FOLDER_NAME), folderName));
                         }
                         String folderId = folderCursor.getString(NOTE_COLUMN_ID);
-                        exportFolderToText(folderId, ps);
-                    } while (folderCursor.moveToNext());
-                }
-                folderCursor.close();
-            }
-
-            // Export notes in root's folder
-            Cursor noteCursor = mContext.getContentResolver().query(
-                    Notes.CONTENT_NOTE_URI,
-                    NOTE_PROJECTION,
-                    NoteColumns.TYPE + "=" + +Notes.TYPE_NOTE + " AND " + NoteColumns.PARENT_ID
-                            + "=0", null, null);
-
-            if (noteCursor != null) {
-                if (noteCursor.moveToFirst()) {
-                    do {
-                        ps.println(String.format(getFormat(FORMAT_NOTE_DATE), DateFormat.format(
-                                mContext.getString(R.string.format_datetime_mdhm),
-                                noteCursor.getLong(NOTE_COLUMN_MODIFIED_DATE))));
-                        // Query data belong to this note
-                        String noteId = noteCursor.getString(NOTE_COLUMN_ID);
-                        exportNoteToText(noteId, ps);
-                    } while (noteCursor.moveToNext());
-                }
-                noteCursor.close();
-            }
-            ps.close();
-
-            return STATE_SUCCESS;
-        }
-
-        /**
-         * Get a print stream pointed to the file {@generateExportedTextFile}
-         */
-        private PrintStream getExportToTextPrintStream() {
-            File file = generateFileMountedOnSDcard(mContext, R.string.file_path,
-                    R.string.file_name_txt_format);
-            if (file == null) {
-                Log.e(TAG, "create file to exported failed");
-                return null;
-            }
-            mFileName = file.getName();
-            mFileDirectory = mContext.getString(R.string.file_path);
-            PrintStream ps = null;
-            try {
-                FileOutputStream fos = new FileOutputStream(file);
-                ps = new PrintStream(fos);
-            } catch (FileNotFoundException e) {
-                e.printStackTrace();
-                return null;
-            } catch (NullPointerException e) {
-                e.printStackTrace();
-                return null;
-            }
-            return ps;
-        }
-    }
-
-    /**
-     * Generate the text file to store imported data
-     */
-    private static File generateFileMountedOnSDcard(Context context, int filePathResId, int fileNameFormatResId) {
-        StringBuilder sb = new StringBuilder();
-        sb.append(Environment.getExternalStorageDirectory());
-        sb.append(context.getString(filePathResId));
-        File filedir = new File(sb.toString());
-        sb.append(context.getString(
-                fileNameFormatResId,
-                DateFormat.format(context.getString(R.string.format_date_ymd),
-                        System.currentTimeMillis())));
-        File file = new File(sb.toString());
-
-        try {
-            if (!filedir.exists()) {
-                filedir.mkdir();
-            }
-            if (!file.exists()) {
-                file.createNewFile();
-            }
-            return file;
-        } catch (SecurityException e) {
-            e.printStackTrace();
-        } catch (IOException e) {
-            e.printStackTrace();
-        }
-
-        return null;
-    }
-}
-
+                        exportFolderToText(folderId
 
diff --git a/src/net/micode/notes/tool/DataUtils.java b/src/net/micode/notes/tool/DataUtils.java
index 2a14982..bdb791b 100644
--- a/src/net/micode/notes/tool/DataUtils.java
+++ b/src/net/micode/notes/tool/DataUtils.java
@@ -34,262 +34,161 @@ import net.micode.notes.ui.NotesListAdapter.AppWidgetAttribute;
 import java.util.ArrayList;
 import java.util.HashSet;
 
-
+/**
+ * 工具类，提供对笔记数据的操作方法。
+ */
 public class DataUtils {
-    public static final String TAG = "DataUtils";
+    public static final String TAG = "DataUtils"; // 定义日志标签
+
+    /**
+     * 批量删除笔记。
+     * @param resolver ContentResolver实例，用于访问数据。
+     * @param ids 要删除的笔记ID集合。
+     * @return 如果删除成功返回true，否则返回false。
+     */
     public static boolean batchDeleteNotes(ContentResolver resolver, HashSet<Long> ids) {
-        if (ids == null) {
+        if (ids == null) { // 检查传入的ID集合是否为空
             Log.d(TAG, "the ids is null");
             return true;
         }
-        if (ids.size() == 0) {
+        if (ids.size() == 0) { // 检查ID集合是否为空
             Log.d(TAG, "no id is in the hashset");
             return true;
         }
 
-        ArrayList<ContentProviderOperation> operationList = new ArrayList<ContentProviderOperation>();
+        ArrayList<ContentProviderOperation> operationList = new ArrayList<ContentProviderOperation>(); // 操作列表，用于批量操作
         for (long id : ids) {
-            if(id == Notes.ID_ROOT_FOLDER) {
+            if(id == Notes.ID_ROOT_FOLDER) { // 检查是否尝试删除根文件夹，这是不允许的
                 Log.e(TAG, "Don't delete system folder root");
                 continue;
             }
             ContentProviderOperation.Builder builder = ContentProviderOperation
-                    .newDelete(ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, id));
-            operationList.add(builder.build());
+                    .newDelete(ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, id)); // 构建删除操作
+            operationList.add(builder.build()); // 将删除操作添加到操作列表
         }
         try {
-            ContentProviderResult[] results = resolver.applyBatch(Notes.AUTHORITY, operationList);
-            if (results == null || results.length == 0 || results[0] == null) {
+            ContentProviderResult[] results = resolver.applyBatch(Notes.AUTHORITY, operationList); // 执行批量操作
+            if (results == null || results.length == 0 || results[0] == null) { // 检查操作结果
                 Log.d(TAG, "delete notes failed, ids:" + ids.toString());
                 return false;
             }
             return true;
-        } catch (RemoteException e) {
+        } catch (RemoteException e) { // 捕获远程异常
             Log.e(TAG, String.format("%s: %s", e.toString(), e.getMessage()));
-        } catch (OperationApplicationException e) {
+        } catch (OperationApplicationException e) { // 捕获操作应用异常
             Log.e(TAG, String.format("%s: %s", e.toString(), e.getMessage()));
         }
-        return false;
+        return false; // 发生异常时返回false
     }
 
+    /**
+     * 将笔记移动到另一个文件夹。
+     * @param resolver ContentResolver实例，用于访问数据。
+     * @param id 要移动的笔记ID。
+     * @param srcFolderId 当前文件夹ID。
+     * @param desFolderId 目标文件夹ID。
+     */
     public static void moveNoteToFoler(ContentResolver resolver, long id, long srcFolderId, long desFolderId) {
-        ContentValues values = new ContentValues();
-        values.put(NoteColumns.PARENT_ID, desFolderId);
-        values.put(NoteColumns.ORIGIN_PARENT_ID, srcFolderId);
-        values.put(NoteColumns.LOCAL_MODIFIED, 1);
-        resolver.update(ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, id), values, null, null);
+        ContentValues values = new ContentValues(); // 创建ContentValues对象，用于更新数据
+        values.put(NoteColumns.PARENT_ID, desFolderId); // 设置新的父ID，即目标文件夹ID
+        values.put(NoteColumns.ORIGIN_PARENT_ID, srcFolderId); // 设置原始的父ID，即当前文件夹ID
+        values.put(NoteColumns.LOCAL_MODIFIED, 1); // 标记笔记为本地修改
+        resolver.update(ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, id), values, null, null); // 更新笔记数据
     }
 
+    /**
+     * 批量将笔记移动到指定文件夹。
+     * @param resolver ContentResolver实例，用于访问数据。
+     * @param ids 要移动的笔记ID集合。
+     * @param folderId 目标文件夹ID。
+     * @return 如果移动成功返回true，否则返回false。
+     */
     public static boolean batchMoveToFolder(ContentResolver resolver, HashSet<Long> ids,
             long folderId) {
-        if (ids == null) {
+        if (ids == null) { // 检查传入的ID集合是否为空
             Log.d(TAG, "the ids is null");
             return true;
         }
 
-        ArrayList<ContentProviderOperation> operationList = new ArrayList<ContentProviderOperation>();
+        ArrayList<ContentProviderOperation> operationList = new ArrayList<ContentProviderOperation>(); // 操作列表，用于批量操作
         for (long id : ids) {
             ContentProviderOperation.Builder builder = ContentProviderOperation
-                    .newUpdate(ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, id));
-            builder.withValue(NoteColumns.PARENT_ID, folderId);
-            builder.withValue(NoteColumns.LOCAL_MODIFIED, 1);
-            operationList.add(builder.build());
+                    .newUpdate(ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, id)); // 构建更新操作
+            builder.withValue(NoteColumns.PARENT_ID, folderId); // 设置新的父ID，即目标文件夹ID
+            builder.withValue(NoteColumns.LOCAL_MODIFIED, 1); // 标记笔记为本地修改
+            operationList.add(builder.build()); // 将更新操作添加到操作列表
         }
 
         try {
-            ContentProviderResult[] results = resolver.applyBatch(Notes.AUTHORITY, operationList);
-            if (results == null || results.length == 0 || results[0] == null) {
+            ContentProviderResult[] results = resolver.applyBatch(Notes.AUTHORITY, operationList); // 执行批量操作
+            if (results == null || results.length == 0 || results[0] == null) { // 检查操作结果
                 Log.d(TAG, "delete notes failed, ids:" + ids.toString());
                 return false;
             }
             return true;
-        } catch (RemoteException e) {
+        } catch (RemoteException e) { // 捕获远程异常
             Log.e(TAG, String.format("%s: %s", e.toString(), e.getMessage()));
-        } catch (OperationApplicationException e) {
+        } catch (OperationApplicationException e) { // 捕获操作应用异常
             Log.e(TAG, String.format("%s: %s", e.toString(), e.getMessage()));
         }
-        return false;
+        return false; // 发生异常时返回false
     }
 
     /**
-     * Get the all folder count except system folders {@link Notes#TYPE_SYSTEM}}
+     * 获取用户文件夹的数量（不包括系统文件夹）。
+     * @param resolver ContentResolver实例，用于访问数据。
+     * @return 用户文件夹的数量。
      */
     public static int getUserFolderCount(ContentResolver resolver) {
-        Cursor cursor =resolver.query(Notes.CONTENT_NOTE_URI,
-                new String[] { "COUNT(*)" },
-                NoteColumns.TYPE + "=? AND " + NoteColumns.PARENT_ID + "<>?",
-                new String[] { String.valueOf(Notes.TYPE_FOLDER), String.valueOf(Notes.ID_TRASH_FOLER)},
+        Cursor cursor = resolver.query(Notes.CONTENT_NOTE_URI, // 查询笔记内容URI
+                new String[] { "COUNT(*)" }, // 查询计数
+                NoteColumns.TYPE + "=? AND " + NoteColumns.PARENT_ID + "<>?", // 查询条件，类型为文件夹且不是垃圾箱
+                new String[] { String.valueOf(Notes.TYPE_FOLDER), String.valueOf(Notes.ID_TRASH_FOLER)}, // 查询参数
                 null);
 
         int count = 0;
-        if(cursor != null) {
-            if(cursor.moveToFirst()) {
+        if (cursor != null) { // 检查游标是否为空
+            if (cursor.moveToFirst()) { // 移动到游标的第一行
                 try {
-                    count = cursor.getInt(0);
-                } catch (IndexOutOfBoundsException e) {
+                    count = cursor.getInt(0); // 获取文件夹数量
+                } catch (IndexOutOfBoundsException e) { // 捕获索引越界异常
                     Log.e(TAG, "get folder count failed:" + e.toString());
                 } finally {
-                    cursor.close();
+                    cursor.close(); // 关闭游标
                 }
             }
         }
-        return count;
+        return count; // 返回文件夹数量
     }
 
+    /**
+     * 检查笔记在数据库中是否可见。
+     * @param resolver ContentResolver实例，用于访问数据。
+     * @param noteId 笔记ID。
+     * @param type 笔记类型。
+     * @return 如果笔记可见返回true，否则返回false。
+     */
     public static boolean visibleInNoteDatabase(ContentResolver resolver, long noteId, int type) {
-        Cursor cursor = resolver.query(ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId),
-                null,
-                NoteColumns.TYPE + "=? AND " + NoteColumns.PARENT_ID + "<>" + Notes.ID_TRASH_FOLER,
-                new String [] {String.valueOf(type)},
+        Cursor cursor = resolver.query(ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), // 查询笔记URI
+                null, // 无特定列
+                NoteColumns.TYPE + "=? AND " + NoteColumns.PARENT_ID + "<>" + Notes.ID_TRASH_FOLER, // 查询条件，类型匹配且不在垃圾箱
+                new String[] {String.valueOf(type)}, // 查询参数
                 null);
 
         boolean exist = false;
-        if (cursor != null) {
-            if (cursor.getCount() > 0) {
-                exist = true;
-            }
-            cursor.close();
-        }
-        return exist;
-    }
-
-    public static boolean existInNoteDatabase(ContentResolver resolver, long noteId) {
-        Cursor cursor = resolver.query(ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId),
-                null, null, null, null);
-
-        boolean exist = false;
-        if (cursor != null) {
-            if (cursor.getCount() > 0) {
-                exist = true;
-            }
-            cursor.close();
-        }
-        return exist;
-    }
-
-    public static boolean existInDataDatabase(ContentResolver resolver, long dataId) {
-        Cursor cursor = resolver.query(ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId),
-                null, null, null, null);
-
-        boolean exist = false;
-        if (cursor != null) {
-            if (cursor.getCount() > 0) {
-                exist = true;
+        if (cursor != null) { // 检查游标是否为空
+            if (cursor.getCount() > 0) { // 检查查询结果数量
+                exist = true; // 设置存在标志为true
             }
-            cursor.close();
+            cursor.close(); // 关闭游标
         }
-        return exist;
+        return exist; // 返回笔记是否存在
     }
 
-    public static boolean checkVisibleFolderName(ContentResolver resolver, String name) {
-        Cursor cursor = resolver.query(Notes.CONTENT_NOTE_URI, null,
-                NoteColumns.TYPE + "=" + Notes.TYPE_FOLDER +
-                " AND " + NoteColumns.PARENT_ID + "<>" + Notes.ID_TRASH_FOLER +
-                " AND " + NoteColumns.SNIPPET + "=?",
-                new String[] { name }, null);
-        boolean exist = false;
-        if(cursor != null) {
-            if(cursor.getCount() > 0) {
-                exist = true;
-            }
-            cursor.close();
-        }
-        return exist;
-    }
-
-    public static HashSet<AppWidgetAttribute> getFolderNoteWidget(ContentResolver resolver, long folderId) {
-        Cursor c = resolver.query(Notes.CONTENT_NOTE_URI,
-                new String[] { NoteColumns.WIDGET_ID, NoteColumns.WIDGET_TYPE },
-                NoteColumns.PARENT_ID + "=?",
-                new String[] { String.valueOf(folderId) },
-                null);
-
-        HashSet<AppWidgetAttribute> set = null;
-        if (c != null) {
-            if (c.moveToFirst()) {
-                set = new HashSet<AppWidgetAttribute>();
-                do {
-                    try {
-                        AppWidgetAttribute widget = new AppWidgetAttribute();
-                        widget.widgetId = c.getInt(0);
-                        widget.widgetType = c.getInt(1);
-                        set.add(widget);
-                    } catch (IndexOutOfBoundsException e) {
-                        Log.e(TAG, e.toString());
-                    }
-                } while (c.moveToNext());
-            }
-            c.close();
-        }
-        return set;
-    }
-
-    public static String getCallNumberByNoteId(ContentResolver resolver, long noteId) {
-        Cursor cursor = resolver.query(Notes.CONTENT_DATA_URI,
-                new String [] { CallNote.PHONE_NUMBER },
-                CallNote.NOTE_ID + "=? AND " + CallNote.MIME_TYPE + "=?",
-                new String [] { String.valueOf(noteId), CallNote.CONTENT_ITEM_TYPE },
-                null);
-
-        if (cursor != null && cursor.moveToFirst()) {
-            try {
-                return cursor.getString(0);
-            } catch (IndexOutOfBoundsException e) {
-                Log.e(TAG, "Get call number fails " + e.toString());
-            } finally {
-                cursor.close();
-            }
-        }
-        return "";
-    }
-
-    public static long getNoteIdByPhoneNumberAndCallDate(ContentResolver resolver, String phoneNumber, long callDate) {
-        Cursor cursor = resolver.query(Notes.CONTENT_DATA_URI,
-                new String [] { CallNote.NOTE_ID },
-                CallNote.CALL_DATE + "=? AND " + CallNote.MIME_TYPE + "=? AND PHONE_NUMBERS_EQUAL("
-                + CallNote.PHONE_NUMBER + ",?)",
-                new String [] { String.valueOf(callDate), CallNote.CONTENT_ITEM_TYPE, phoneNumber },
-                null);
-
-        if (cursor != null) {
-            if (cursor.moveToFirst()) {
-                try {
-                    return cursor.getLong(0);
-                } catch (IndexOutOfBoundsException e) {
-                    Log.e(TAG, "Get call note id fails " + e.toString());
-                }
-            }
-            cursor.close();
-        }
-        return 0;
-    }
-
-    public static String getSnippetById(ContentResolver resolver, long noteId) {
-        Cursor cursor = resolver.query(Notes.CONTENT_NOTE_URI,
-                new String [] { NoteColumns.SNIPPET },
-                NoteColumns.ID + "=?",
-                new String [] { String.valueOf(noteId)},
-                null);
-
-        if (cursor != null) {
-            String snippet = "";
-            if (cursor.moveToFirst()) {
-                snippet = cursor.getString(0);
-            }
-            cursor.close();
-            return snippet;
-        }
-        throw new IllegalArgumentException("Note is not found with id: " + noteId);
-    }
-
-    public static String getFormattedSnippet(String snippet) {
-        if (snippet != null) {
-            snippet = snippet.trim();
-            int index = snippet.indexOf('\n');
-            if (index != -1) {
-                snippet = snippet.substring(0, index);
-            }
-        }
-        return snippet;
-    }
-}
+    /**
+     * 检查笔记在数据库中是否存在。
+     * @param resolver ContentResolver实例，用于访问数据。
+     * @param noteId 笔记ID。
+     * @return 如果笔记存在返回true，否则返回false。
+     */
+    public static boolean existInNoteDatabase(ContentResolver resolver, long noteId)
\ No newline at end of file
diff --git a/src/net/micode/notes/tool/GTaskStringUtils.java b/src/net/micode/notes/tool/GTaskStringUtils.java
index 666b729..86f3920 100644
--- a/src/net/micode/notes/tool/GTaskStringUtils.java
+++ b/src/net/micode/notes/tool/GTaskStringUtils.java
@@ -17,97 +17,98 @@
 package net.micode.notes.tool;
 
 public class GTaskStringUtils {
-
+    // 定义GTASK_JSON_ACTION_ID常量，用于标识动作ID
     public final static String GTASK_JSON_ACTION_ID = "action_id";
-
+    // 定义GTASK_JSON_ACTION_LIST常量，用于标识动作列表
     public final static String GTASK_JSON_ACTION_LIST = "action_list";
-
+    // 定义GTASK_JSON_ACTION_TYPE常量，用于标识动作类型
     public final static String GTASK_JSON_ACTION_TYPE = "action_type";
-
+    // 定义GTASK_JSON_ACTION_TYPE_CREATE常量，表示创建动作
     public final static String GTASK_JSON_ACTION_TYPE_CREATE = "create";
-
+    // 定义GTASK_JSON_ACTION_TYPE_GETALL常量，表示获取所有动作
     public final static String GTASK_JSON_ACTION_TYPE_GETALL = "get_all";
-
+    // 定义GTASK_JSON_ACTION_TYPE_MOVE常量，表示移动动作
     public final static String GTASK_JSON_ACTION_TYPE_MOVE = "move";
-
+    // 定义GTASK_JSON_ACTION_TYPE_UPDATE常量，表示更新动作
     public final static String GTASK_JSON_ACTION_TYPE_UPDATE = "update";
-
+    // 定义GTASK_JSON_CREATOR_ID常量，用于标识创建者ID
     public final static String GTASK_JSON_CREATOR_ID = "creator_id";
-
+    // 定义GTASK_JSON_CHILD_ENTITY常量，用于标识子实体
     public final static String GTASK_JSON_CHILD_ENTITY = "child_entity";
-
+    // 定义GTASK_JSON_CLIENT_VERSION常量，用于标识客户端版本
     public final static String GTASK_JSON_CLIENT_VERSION = "client_version";
-
+    // 定义GTASK_JSON_COMPLETED常量，用于标识任务是否完成
     public final static String GTASK_JSON_COMPLETED = "completed";
-
+    // 定义GTASK_JSON_CURRENT_LIST_ID常量，用于标识当前列表ID
     public final static String GTASK_JSON_CURRENT_LIST_ID = "current_list_id";
-
+    // 定义GTASK_JSON_DEFAULT_LIST_ID常量，用于标识默认列表ID
     public final static String GTASK_JSON_DEFAULT_LIST_ID = "default_list_id";
-
+    // 定义GTASK_JSON_DELETED常量，用于标识任务是否被删除
     public final static String GTASK_JSON_DELETED = "deleted";
-
+    // 定义GTASK_JSON_DEST_LIST常量，用于标识目标列表
     public final static String GTASK_JSON_DEST_LIST = "dest_list";
-
+    // 定义GTASK_JSON_DEST_PARENT常量，用于标识目标父任务
     public final static String GTASK_JSON_DEST_PARENT = "dest_parent";
-
+    // 定义GTASK_JSON_DEST_PARENT_TYPE常量，用于标识目标父任务类型
     public final static String GTASK_JSON_DEST_PARENT_TYPE = "dest_parent_type";
-
+    // 定义GTASK_JSON_ENTITY_DELTA常量，用于标识实体变化
     public final static String GTASK_JSON_ENTITY_DELTA = "entity_delta";
-
+    // 定义GTASK_JSON_ENTITY_TYPE常量，用于标识实体类型
     public final static String GTASK_JSON_ENTITY_TYPE = "entity_type";
-
+    // 定义GTASK_JSON_GET_DELETED常量，表示获取已删除的任务
     public final static String GTASK_JSON_GET_DELETED = "get_deleted";
-
+    // 定义GTASK_JSON_ID常量，用于标识任务ID
     public final static String GTASK_JSON_ID = "id";
-
+    // 定义GTASK_JSON_INDEX常量，用于标识任务在列表中的索引
     public final static String GTASK_JSON_INDEX = "index";
-
+    // 定义GTASK_JSON_LAST_MODIFIED常量，用于标识任务最后修改时间
     public final static String GTASK_JSON_LAST_MODIFIED = "last_modified";
-
+    // 定义GTASK_JSON_LATEST_SYNC_POINT常量，用于标识最新的同步点
     public final static String GTASK_JSON_LATEST_SYNC_POINT = "latest_sync_point";
-
+    // 定义GTASK_JSON_LIST_ID常量，用于标识列表ID
     public final static String GTASK_JSON_LIST_ID = "list_id";
-
+    // 定义GTASK_JSON_LISTS常量，用于标识列表集合
     public final static String GTASK_JSON_LISTS = "lists";
-
+    // 定义GTASK_JSON_NAME常量，用于标识任务或列表的名称
     public final static String GTASK_JSON_NAME = "name";
-
+    // 定义GTASK_JSON_NEW_ID常量，用于标识新的任务ID
     public final static String GTASK_JSON_NEW_ID = "new_id";
-
+    // 定义GTASK_JSON_NOTES常量，用于标识任务的备注信息
     public final static String GTASK_JSON_NOTES = "notes";
-
+    // 定义GTASK_JSON_PARENT_ID常量，用于标识父任务ID
     public final static String GTASK_JSON_PARENT_ID = "parent_id";
-
+    // 定义GTASK_JSON_PRIOR_SIBLING_ID常量，用于标识前一个兄弟任务ID
     public final static String GTASK_JSON_PRIOR_SIBLING_ID = "prior_sibling_id";
-
+    // 定义GTASK_JSON_RESULTS常量，用于标识操作结果
     public final static String GTASK_JSON_RESULTS = "results";
-
+    // 定义GTASK_JSON_SOURCE_LIST常量，用于标识源列表
     public final static String GTASK_JSON_SOURCE_LIST = "source_list";
-
+    // 定义GTASK_JSON_TASKS常量，用于标识任务集合
     public final static String GTASK_JSON_TASKS = "tasks";
-
+    // 定义GTASK_JSON_TYPE常量，用于标识实体类型
     public final static String GTASK_JSON_TYPE = "type";
-
+    // 定义GTASK_JSON_TYPE_GROUP常量，表示分组类型
     public final static String GTASK_JSON_TYPE_GROUP = "GROUP";
-
+    // 定义GTASK_JSON_TYPE_TASK常量，表示任务类型
     public final static String GTASK_JSON_TYPE_TASK = "TASK";
-
+    // 定义GTASK_JSON_USER常量，用于标识用户信息
     public final static String GTASK_JSON_USER = "user";
 
+    // 定义MIUI_FOLDER_PREFFIX常量，用于标识MIUI笔记的文件夹前缀
     public final static String MIUI_FOLDER_PREFFIX = "[MIUI_Notes]";
-
+    // 定义FOLDER_DEFAULT常量，用于标识默认文件夹名称
     public final static String FOLDER_DEFAULT = "Default";
-
+    // 定义FOLDER_CALL_NOTE常量，用于标识通话记录文件夹名称
     public final static String FOLDER_CALL_NOTE = "Call_Note";
-
+    // 定义FOLDER_META常量，用于标识元数据文件夹名称
     public final static String FOLDER_META = "METADATA";
 
+    // 定义META_HEAD_GTASK_ID常量，用于标识元数据中的GTask ID
     public final static String META_HEAD_GTASK_ID = "meta_gid";
-
+    // 定义META_HEAD_NOTE常量，用于标识元数据中的笔记信息
     public final static String META_HEAD_NOTE = "meta_note";
-
+    // 定义META_HEAD_DATA常量，用于标识元数据中的其他数据
     public final static String META_HEAD_DATA = "meta_data";
-
+    // 定义META_NOTE_NAME常量，用于标识元数据笔记的名称，警告不要更新或删除
     public final static String META_NOTE_NAME = "[META INFO] DON'T UPDATE AND DELETE";
-
-}
+}
\ No newline at end of file
diff --git a/src/net/micode/notes/tool/ResourceParser.java b/src/net/micode/notes/tool/ResourceParser.java
index 1ad3ad6..0b475e9 100644
--- a/src/net/micode/notes/tool/ResourceParser.java
+++ b/src/net/micode/notes/tool/ResourceParser.java
@@ -22,24 +22,35 @@ import android.preference.PreferenceManager;
 import net.micode.notes.R;
 import net.micode.notes.ui.NotesPreferenceActivity;
 
+/**
+ * 资源解析工具类，用于管理不同颜色和字体大小的资源ID。
+ */
 public class ResourceParser {
 
+    // 定义颜色常量
     public static final int YELLOW           = 0;
     public static final int BLUE             = 1;
     public static final int WHITE            = 2;
     public static final int GREEN            = 3;
     public static final int RED              = 4;
 
+    // 定义默认背景颜色常量
     public static final int BG_DEFAULT_COLOR = YELLOW;
 
+    // 定义字体大小常量
     public static final int TEXT_SMALL       = 0;
     public static final int TEXT_MEDIUM      = 1;
     public static final int TEXT_LARGE       = 2;
     public static final int TEXT_SUPER       = 3;
 
+    // 定义默认字体大小常量
     public static final int BG_DEFAULT_FONT_SIZE = TEXT_MEDIUM;
 
+    /**
+     * 笔记背景资源类，用于获取不同颜色的笔记背景资源ID。
+     */
     public static class NoteBgResources {
+        // 定义编辑状态下不同颜色的笔记背景资源ID数组
         private final static int [] BG_EDIT_RESOURCES = new int [] {
             R.drawable.edit_yellow,
             R.drawable.edit_blue,
@@ -48,6 +59,7 @@ public class ResourceParser {
             R.drawable.edit_red
         };
 
+        // 定义编辑状态下不同颜色的笔记标题背景资源ID数组
         private final static int [] BG_EDIT_TITLE_RESOURCES = new int [] {
             R.drawable.edit_title_yellow,
             R.drawable.edit_title_blue,
@@ -56,15 +68,21 @@ public class ResourceParser {
             R.drawable.edit_title_red
         };
 
+        // 获取编辑状态下指定颜色的笔记背景资源ID
         public static int getNoteBgResource(int id) {
             return BG_EDIT_RESOURCES[id];
         }
 
+        // 获取编辑状态下指定颜色的笔记标题背景资源ID
         public static int getNoteTitleBgResource(int id) {
             return BG_EDIT_TITLE_RESOURCES[id];
         }
     }
 
+    /**
+     * 获取默认的背景ID。
+     * 如果设置了自定义背景颜色，则随机返回一个背景ID，否则返回默认背景ID。
+     */
     public static int getDefaultBgId(Context context) {
         if (PreferenceManager.getDefaultSharedPreferences(context).getBoolean(
                 NotesPreferenceActivity.PREFERENCE_SET_BG_COLOR_KEY, false)) {
@@ -74,7 +92,11 @@ public class ResourceParser {
         }
     }
 
+    /**
+     * 笔记项背景资源类，用于获取不同位置（首项、末项、单项、普通项）的笔记背景资源ID。
+     */
     public static class NoteItemBgResources {
+        // 定义列表中首项不同颜色的笔记背景资源ID数组
         private final static int [] BG_FIRST_RESOURCES = new int [] {
             R.drawable.list_yellow_up,
             R.drawable.list_blue_up,
@@ -83,6 +105,7 @@ public class ResourceParser {
             R.drawable.list_red_up
         };
 
+        // 定义列表中普通项不同颜色的笔记背景资源ID数组
         private final static int [] BG_NORMAL_RESOURCES = new int [] {
             R.drawable.list_yellow_middle,
             R.drawable.list_blue_middle,
@@ -91,6 +114,7 @@ public class ResourceParser {
             R.drawable.list_red_middle
         };
 
+        // 定义列表中末项不同颜色的笔记背景资源ID数组
         private final static int [] BG_LAST_RESOURCES = new int [] {
             R.drawable.list_yellow_down,
             R.drawable.list_blue_down,
@@ -99,6 +123,7 @@ public class ResourceParser {
             R.drawable.list_red_down,
         };
 
+        // 定义列表中单项不同颜色的笔记背景资源ID数组
         private final static int [] BG_SINGLE_RESOURCES = new int [] {
             R.drawable.list_yellow_single,
             R.drawable.list_blue_single,
@@ -107,28 +132,37 @@ public class ResourceParser {
             R.drawable.list_red_single
         };
 
+        // 获取列表中首项指定颜色的笔记背景资源ID
         public static int getNoteBgFirstRes(int id) {
             return BG_FIRST_RESOURCES[id];
         }
 
+        // 获取列表中末项指定颜色的笔记背景资源ID
         public static int getNoteBgLastRes(int id) {
             return BG_LAST_RESOURCES[id];
         }
 
+        // 获取列表中单项指定颜色的笔记背景资源ID
         public static int getNoteBgSingleRes(int id) {
             return BG_SINGLE_RESOURCES[id];
         }
 
+        // 获取列表中普通项指定颜色的笔记背景资源ID
         public static int getNoteBgNormalRes(int id) {
             return BG_NORMAL_RESOURCES[id];
         }
 
+        // 获取文件夹背景资源ID
         public static int getFolderBgRes() {
             return R.drawable.list_folder;
         }
     }
 
+    /**
+     * 部件背景资源类，用于获取不同大小（2x2和4x4）的部件背景资源ID。
+     */
     public static class WidgetBgResources {
+        // 定义2x2大小不同颜色的部件背景资源ID数组
         private final static int [] BG_2X_RESOURCES = new int [] {
             R.drawable.widget_2x_yellow,
             R.drawable.widget_2x_blue,
@@ -137,10 +171,12 @@ public class ResourceParser {
             R.drawable.widget_2x_red,
         };
 
+        // 获取2x2大小指定颜色的部件背景资源ID
         public static int getWidget2xBgResource(int id) {
             return BG_2X_RESOURCES[id];
         }
 
+        // 定义4x4大小不同颜色的部件背景资源ID数组
         private final static int [] BG_4X_RESOURCES = new int [] {
             R.drawable.widget_4x_yellow,
             R.drawable.widget_4x_blue,
@@ -149,12 +185,17 @@ public class ResourceParser {
             R.drawable.widget_4x_red
         };
 
+        // 获取4x4大小指定颜色的部件背景资源ID
         public static int getWidget4xBgResource(int id) {
             return BG_4X_RESOURCES[id];
         }
     }
 
+    /**
+     * 文本外观资源类，用于获取不同大小的文本外观资源ID。
+     */
     public static class TextAppearanceResources {
+        // 定义不同大小的文本外观资源ID数组
         private final static int [] TEXTAPPEARANCE_RESOURCES = new int [] {
             R.style.TextAppearanceNormal,
             R.style.TextAppearanceMedium,
@@ -162,6 +203,7 @@ public class ResourceParser {
             R.style.TextAppearanceSuper
         };
 
+        // 获取指定大小的文本外观资源ID
         public static int getTexAppearanceResource(int id) {
             /**
              * HACKME: Fix bug of store the resource id in shared preference.
@@ -174,8 +216,9 @@ public class ResourceParser {
             return TEXTAPPEARANCE_RESOURCES[id];
         }
 
+        // 获取文本外观资源数组的大小
         public static int getResourcesSize() {
             return TEXTAPPEARANCE_RESOURCES.length;
         }
     }
-}
+}
\ No newline at end of file