diff --git a/Contact.java b/Contact.java
new file mode 100644
index 0000000..119de7a
--- /dev/null
+++ b/Contact.java
@@ -0,0 +1,91 @@
+/*
+ * 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;
+import android.database.Cursor;
+import android.provider.ContactsContract.CommonDataKinds.Phone;
+import android.provider.ContactsContract.Data;
+import android.telephony.PhoneNumberUtils;
+import android.util.Log;
+
+import java.util.HashMap;
+
+public class Contact {
+    // 静态缓存，用于存储已查询过的电话号码对应的联系人姓名
+    private static HashMap<String, String> sContactCache;
+    // 用于日志记录的标签
+    private static final String TAG = "Contact";
+
+    // 查询条件，用于根据电话号码查询联系人姓名
+    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 = '+')";
+
+    /**
+     * 获取电话号码对应的联系人姓名
+     * @param context 应用程序的上下文
+     * @param phoneNumber 要查询的电话号码
+     * @return 返回电话号码对应的联系人姓名，如果找不到则返回null
+     */
+    public static String getContact(Context context, String phoneNumber) {
+        // 初始化缓存
+        if(sContactCache == null) {
+            sContactCache = new HashMap<String, String>();
+        }
+
+        // 如果缓存中已经有该电话号码的联系人信息，直接返回
+        if(sContactCache.containsKey(phoneNumber)) {
+            return sContactCache.get(phoneNumber);
+        }
+
+        // 使用电话号码生成查询条件
+        String selection = CALLER_ID_SELECTION.replace("+",
+                PhoneNumberUtils.toCallerIDMinMatch(phoneNumber));
+
+        // 查询联系人信息
+        Cursor cursor = context.getContentResolver().query(
+                Data.CONTENT_URI,
+                new String [] { Phone.DISPLAY_NAME },  // 需要获取的字段，这里是联系人姓名
+                selection,  // 查询条件
+                new String[] { phoneNumber },  // 查询参数，填充到查询条件中
+                null);  // 排序方式，null表示不排序
+
+        // 检查查询结果并返回联系人姓名
+        if (cursor != null && cursor.moveToFirst()) {
+            try {
+                String name = cursor.getString(0);  // 获取查询到的联系人姓名
+                sContactCache.put(phoneNumber, name);  // 将结果缓存起来
+                return name;  // 返回联系人姓名
+            } catch (IndexOutOfBoundsException e) {
+                // 捕捉异常并记录错误日志
+                Log.e(TAG, " Cursor get string error " + e.toString());
+                return null;
+            } finally {
+                // 关闭游标，释放资源
+                cursor.close();
+            }
+        } else {
+            // 如果没有匹配的联系人，记录日志并返回null
+            Log.d(TAG, "No contact matched with number:" + phoneNumber);
+            return null;
+        }
+    }
+}
diff --git a/README.md b/README.md
deleted file mode 100644
index a6ed909..0000000
--- a/README.md
+++ /dev/null
@@ -1,2 +0,0 @@
-# note
-
diff --git a/src/Contact.java b/src/Contact.java
new file mode 100644
index 0000000..119de7a
--- /dev/null
+++ b/src/Contact.java
@@ -0,0 +1,91 @@
+/*
+ * 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;
+import android.database.Cursor;
+import android.provider.ContactsContract.CommonDataKinds.Phone;
+import android.provider.ContactsContract.Data;
+import android.telephony.PhoneNumberUtils;
+import android.util.Log;
+
+import java.util.HashMap;
+
+public class Contact {
+    // 静态缓存，用于存储已查询过的电话号码对应的联系人姓名
+    private static HashMap<String, String> sContactCache;
+    // 用于日志记录的标签
+    private static final String TAG = "Contact";
+
+    // 查询条件，用于根据电话号码查询联系人姓名
+    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 = '+')";
+
+    /**
+     * 获取电话号码对应的联系人姓名
+     * @param context 应用程序的上下文
+     * @param phoneNumber 要查询的电话号码
+     * @return 返回电话号码对应的联系人姓名，如果找不到则返回null
+     */
+    public static String getContact(Context context, String phoneNumber) {
+        // 初始化缓存
+        if(sContactCache == null) {
+            sContactCache = new HashMap<String, String>();
+        }
+
+        // 如果缓存中已经有该电话号码的联系人信息，直接返回
+        if(sContactCache.containsKey(phoneNumber)) {
+            return sContactCache.get(phoneNumber);
+        }
+
+        // 使用电话号码生成查询条件
+        String selection = CALLER_ID_SELECTION.replace("+",
+                PhoneNumberUtils.toCallerIDMinMatch(phoneNumber));
+
+        // 查询联系人信息
+        Cursor cursor = context.getContentResolver().query(
+                Data.CONTENT_URI,
+                new String [] { Phone.DISPLAY_NAME },  // 需要获取的字段，这里是联系人姓名
+                selection,  // 查询条件
+                new String[] { phoneNumber },  // 查询参数，填充到查询条件中
+                null);  // 排序方式，null表示不排序
+
+        // 检查查询结果并返回联系人姓名
+        if (cursor != null && cursor.moveToFirst()) {
+            try {
+                String name = cursor.getString(0);  // 获取查询到的联系人姓名
+                sContactCache.put(phoneNumber, name);  // 将结果缓存起来
+                return name;  // 返回联系人姓名
+            } catch (IndexOutOfBoundsException e) {
+                // 捕捉异常并记录错误日志
+                Log.e(TAG, " Cursor get string error " + e.toString());
+                return null;
+            } finally {
+                // 关闭游标，释放资源
+                cursor.close();
+            }
+        } else {
+            // 如果没有匹配的联系人，记录日志并返回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..62dbfac
--- /dev/null
+++ b/src/Notes.java
@@ -0,0 +1,206 @@
+/*
+ * 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.net.Uri;
+
+public class Notes {
+    // 认证标识符，用于在内容提供者中区分不同的数据集合
+    public static final String AUTHORITY = "micode_notes";
+
+    // 用于日志记录的标签
+    public static final String TAG = "Notes";
+
+    // 用于表示不同类型的文件
+    public static final int TYPE_NOTE = 0;
+    public static final int TYPE_FOLDER = 1;
+    public static final int TYPE_SYSTEM = 2;
+
+    /**
+     * 以下ID是系统文件夹的标识符
+     * {@link Notes#ID_ROOT_FOLDER} 表示默认文件夹
+     * {@link Notes#ID_TEMPARAY_FOLDER} 表示临时文件夹
+     * {@link Notes#ID_CALL_RECORD_FOLDER} 表示用于存储通话记录的文件夹
+     */
+    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;
+
+    // Intent 额外数据的键，用于传递提醒日期、背景颜色、Widget ID、文件夹ID等信息
+    public static final String INTENT_EXTRA_ALERT_DATE = "net.micode.notes.alert_date";
+    public static final String INTENT_EXTRA_BACKGROUND_ID = "net.micode.notes.background_color_id";
+    public static final String INTENT_EXTRA_WIDGET_ID = "net.micode.notes.widget_id";
+    public static final String INTENT_EXTRA_WIDGET_TYPE = "net.micode.notes.widget_type";
+    public static final String INTENT_EXTRA_FOLDER_ID = "net.micode.notes.folder_id";
+    public static final String INTENT_EXTRA_CALL_DATE = "net.micode.notes.call_date";
+
+    // Widget 类型常量
+    public static final int TYPE_WIDGET_INVALIDE = -1;
+    public static final int TYPE_WIDGET_2X = 0;
+    public static final int TYPE_WIDGET_4X = 1;
+
+    public static class DataConstants {
+        // 文本便签的 MIME 类型
+        public static final String NOTE = TextNote.CONTENT_ITEM_TYPE;
+        // 通话记录便签的 MIME 类型
+        public static final String CALL_NOTE = CallNote.CONTENT_ITEM_TYPE;
+    }
+
+    /**
+     * Uri 用于查询所有的便签和文件夹
+     */
+    public static final Uri CONTENT_NOTE_URI = Uri.parse("content://" + AUTHORITY + "/note");
+
+    /**
+     * Uri 用于查询具体数据
+     */
+    public static final Uri CONTENT_DATA_URI = Uri.parse("content://" + AUTHORITY + "/data");
+
+    /**
+     * NoteColumns 接口定义了便签和文件夹表中的列
+     */
+    public interface NoteColumns {
+        // 唯一标识符
+        public static final String ID = "_id";
+
+        // 父文件夹的 ID
+        public static final String PARENT_ID = "parent_id";
+
+        // 创建日期
+        public static final String CREATED_DATE = "created_date";
+
+        // 最新修改日期
+        public static final String MODIFIED_DATE = "modified_date";
+
+        // 提醒日期
+        public static final String ALERTED_DATE = "alert_date";
+
+        // 文件夹名称或便签内容的摘要
+        public static final String SNIPPET = "snippet";
+
+        // 便签对应的 Widget ID
+        public static final String WIDGET_ID = "widget_id";
+
+        // 便签对应的 Widget 类型
+        public static final String WIDGET_TYPE = "widget_type";
+
+        // 便签的背景颜色 ID
+        public static final String BG_COLOR_ID = "bg_color_id";
+
+        // 是否有附件，1 表示有，0 表示无
+        public static final String HAS_ATTACHMENT = "has_attachment";
+
+        // 文件夹中的便签数量
+        public static final String NOTES_COUNT = "notes_count";
+
+        // 文件类型：文件夹或便签
+        public static final String TYPE = "type";
+
+        // 最近同步的 ID
+        public static final String SYNC_ID = "sync_id";
+
+        // 本地修改标记
+        public static final String LOCAL_MODIFIED = "local_modified";
+
+        // 移动到临时文件夹之前的原父文件夹 ID
+        public static final String ORIGIN_PARENT_ID = "origin_parent_id";
+
+        // Gtask 的 ID
+        public static final String GTASK_ID = "gtask_id";
+
+        // 版本号
+        public static final String VERSION = "version";
+    }
+
+    /**
+     * DataColumns 接口定义了数据表中的列
+     */
+    public interface DataColumns {
+        // 唯一标识符
+        public static final String ID = "_id";
+
+        // MIME 类型
+        public static final String MIME_TYPE = "mime_type";
+
+        // 关联的便签 ID
+        public static final String NOTE_ID = "note_id";
+
+        // 创建日期
+        public static final String CREATED_DATE = "created_date";
+
+        // 最新修改日期
+        public static final String MODIFIED_DATE = "modified_date";
+
+        // 数据内容
+        public static final String CONTENT = "content";
+
+        // 通用数据列，用于存储整数类型数据
+        public static final String DATA1 = "data1";
+
+        // 通用数据列，用于存储整数类型数据
+        public static final String DATA2 = "data2";
+
+        // 通用数据列，用于存储文本类型数据
+        public static final String DATA3 = "data3";
+
+        // 通用数据列，用于存储文本类型数据
+        public static final String DATA4 = "data4";
+
+        // 通用数据列，用于存储文本类型数据
+        public static final String DATA5 = "data5";
+    }
+
+    /**
+     * TextNote 类继承自 DataColumns，专门处理文本便签相关的数据
+     */
+    public static final class TextNote implements DataColumns {
+        // 模式，表示便签是否处于检查列表模式，1 为检查列表模式，0 为普通模式
+        public static final String MODE = DATA1;
+
+        public static final int MODE_CHECK_LIST = 1;
+
+        // MIME 类型，用于表示文本便签的集合
+        public static final String CONTENT_TYPE = "vnd.android.cursor.dir/text_note";
+
+        // MIME 类型，用于表示单个文本便签
+        public static final String CONTENT_ITEM_TYPE = "vnd.android.cursor.item/text_note";
+
+        // Uri 用于查询文本便签
+        public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY + "/text_note");
+    }
+
+    /**
+     * CallNote 类继承自 DataColumns，专门处理通话记录便签相关的数据
+     */
+    public static final class CallNote implements DataColumns {
+        // 通话日期
+        public static final String CALL_DATE = DATA1;
+
+        // 通话的电话号码
+        public static final String PHONE_NUMBER = DATA3;
+
+        // MIME 类型，用于表示通话记录便签的集合
+        public static final String CONTENT_TYPE = "vnd.android.cursor.dir/call_note";
+
+        // MIME 类型，用于表示单个通话记录便签
+        public static final String CONTENT_ITEM_TYPE = "vnd.android.cursor.item/call_note";
+
+        // Uri 用于查询通话记录便签
+        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..fa468e0
--- /dev/null
+++ b/src/NotesDatabaseHelper.java
@@ -0,0 +1,283 @@
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.micode.notes.data;
+
+import android.content.ContentValues;
+import android.content.Context;
+import android.database.sqlite.SQLiteDatabase;
+import android.database.sqlite.SQLiteOpenHelper;
+import android.util.Log;
+
+import net.micode.notes.data.Notes.DataColumns;
+import net.micode.notes.data.Notes.DataConstants;
+import net.micode.notes.data.Notes.NoteColumns;
+
+/**
+ * NotesDatabaseHelper类用于管理数据库的创建和升级，继承自SQLiteOpenHelper类。
+ */
+public class NotesDatabaseHelper extends SQLiteOpenHelper {
+    // 数据库名
+    private static final String DB_NAME = "note.db";
+    // 数据库版本
+    private static final int DB_VERSION = 4;
+
+    // 数据表的名称
+    public interface TABLE {
+        public static final String NOTE = "note";
+        public static final String DATA = "data";
+    }
+
+    private static final String TAG = "NotesDatabaseHelper";
+
+    // 单例模式
+    private static NotesDatabaseHelper mInstance;
+
+    // 创建note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 ''" +
+        ")";
+
+    // 创建data表中NOTE_ID的索引
+    private static final String CREATE_DATA_NOTE_ID_INDEX_SQL =
+        "CREATE INDEX IF NOT EXISTS note_id_index ON " +
+        TABLE.DATA + "(" + DataColumns.NOTE_ID + ");";
+
+    /**
+     * 增加文件夹中的笔记数，当笔记移动到该文件夹时
+     */
+    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";
+
+    /**
+     * 减少文件夹中的笔记数，当笔记从该文件夹中移除时
+     */
+    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";
+
+    /**
+     * 增加文件夹中的笔记数，当插入新的笔记到该文件夹时
+     */
+    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";
+
+    /**
+     * 减少文件夹中的笔记数，当从该文件夹删除笔记时
+     */
+    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NOTE的数据时更新笔记内容
+     */
+    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";
+
+    /**
+     * 当类型为NOTE的数据更新时，更新笔记内容
+     */
+    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";
+
+    /**
+     * 当类型为NOTE的数据删除时，更新笔记内容
+     */
+    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";
+
+    /**
+     * 当笔记被删除时，删除相关数据
+     */
+    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";
+
+    /**
+     * 当文件夹被删除时，删除该文件夹中的笔记
+     */
+    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";
+
+    /**
+     * 获取数据库实例，确保数据库只有一个实例
+     *
+     * @param context 应用上下文
+     * @return 数据库实例
+     */
+    public static synchronized NotesDatabaseHelper getInstance(Context context) {
+        if (mInstance == null) {
+            mInstance = new NotesDatabaseHelper(context);
+        }
+        return mInstance;
+    }
+
+    /**
+     * 构造函数，初始化数据库
+     *
+     * @param context 应用上下文
+     */
+    private NotesDatabaseHelper(Context context) {
+        super(context, DB_NAME, null, DB_VERSION);
+    }
+
+    /**
+     * 创建数据库，初始化数据表
+     *
+     * @param db SQLite数据库实例
+     */
+    @Override
+    public void onCreate(SQLiteDatabase db) {
+        Log.d(TAG, "onCreate");
+        db.execSQL(CREATE_NOTE_TABLE_SQL);
+        db.execSQL(CREATE_DATA_TABLE_SQL);
+        db.execSQL(CREATE_DATA_NOTE_ID_INDEX_SQL);
+
+        db.execSQL(NOTE_INCREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER);
+        db.execSQL(NOTE_DECREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER);
+        db.execSQL(NOTE_INCREASE_FOLDER_COUNT_ON_INSERT_TRIGGER);
+        db.execSQL(NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER);
+
+        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);
+
+        db.execSQL(NOTE_DELETE_DATA_ON_DELETE_TRIGGER);
+        db.execSQL(FOLDER_DELETE_NOTES_ON_DELETE_TRIGGER);
+
+        // 初始化默认文件夹
+        initDefaultFolder(db);
+    }
+
+    /**
+     * 更新数据库，处理数据库版本升级
+     *
+     * @param db         SQLite数据库实例
+     * @param oldVersion 旧版本号
+     * @param newVersion 新版本号
+     */
+    @Override
+    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
+        Log.d(TAG, "onUpgrade");
+        // 这里可以根据不同版本号处理升级逻辑，当前暂时删除旧表并重新创建
+        if (oldVersion != newVersion) {
+            db.execSQL("DROP TABLE IF EXISTS " + TABLE.NOTE);
+            db.execSQL("DROP TABLE IF EXISTS " + TABLE.DATA);
+            onCreate(db);
+        }
+    }
+
+    /**
+     * 初始化默认文件夹，在第一次创建数据库时调用
+     *
+     * @param db SQLite数据库实例
+     */
+    private void initDefaultFolder(SQLiteDatabase db) {
+        ContentValues values = new ContentValues();
+        values.put(NoteColumns.ID, Notes.ID_ROOT_FOLDER);
+        values.put(NoteColumns.SNIPPET, "ROOT");
+        values.put(NoteColumns.TYPE, Notes.TYPE_FOLDER);
+        db.insert(TABLE.NOTE, null, values);
+    }
+}
diff --git a/src/NotesProvider.java b/src/NotesProvider.java
new file mode 100644
index 0000000..fc946d1
--- /dev/null
+++ b/src/NotesProvider.java
@@ -0,0 +1,354 @@
+/*
+ * 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;
+
+/**
+ * NotesProvider是内容提供者类，负责提供与笔记数据的增删改查功能。 
+ * 它通过SQLite数据库进行数据存储，并使用UriMatcher来解析URI请求。
+ */
+public class NotesProvider extends ContentProvider {
+
+    // 定义UriMatcher对象，用于匹配不同类型的URI
+    private static final UriMatcher mMatcher;
+
+    // Notes数据库帮助类，用于操作数据库
+    private NotesDatabaseHelper mHelper;
+
+    // 日志TAG
+    private static final String TAG = "NotesProvider";
+
+    // 定义不同的URI匹配码
+    private static final int URI_NOTE = 1;           // 匹配所有笔记
+    private static final int URI_NOTE_ITEM = 2;      // 匹配单个笔记
+    private static final int URI_DATA = 3;           // 匹配所有数据
+    private static final int URI_DATA_ITEM = 4;      // 匹配单个数据
+    private static final int URI_SEARCH = 5;         // 匹配搜索请求
+    private static final int URI_SEARCH_SUGGEST = 6; // 匹配搜索建议请求
+
+    // 静态代码块，用于初始化UriMatcher
+    static {
+        mMatcher = new UriMatcher(UriMatcher.NO_MATCH);
+        mMatcher.addURI(Notes.AUTHORITY, "note", URI_NOTE); // 匹配笔记URI
+        mMatcher.addURI(Notes.AUTHORITY, "note/#", URI_NOTE_ITEM); // 匹配具体的笔记
+        mMatcher.addURI(Notes.AUTHORITY, "data", URI_DATA); // 匹配数据URI
+        mMatcher.addURI(Notes.AUTHORITY, "data/#", URI_DATA_ITEM); // 匹配具体的数据
+        mMatcher.addURI(Notes.AUTHORITY, "search", URI_SEARCH); // 匹配搜索
+        mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY, URI_SEARCH_SUGGEST); // 搜索建议
+        mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY + "/*", URI_SEARCH_SUGGEST);
+    }
+
+    /**
+     * SQL查询片段，用于从笔记中搜索，删除换行符并裁剪空格，以显示更多信息。
+     */
+    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，用于搜索笔记内容中的摘要
+    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实例时调用。
+     * 主要用于初始化数据库帮助类实例。
+     */
+    @Override
+    public boolean onCreate() {
+        mHelper = NotesDatabaseHelper.getInstance(getContext());
+        return true;
+    }
+
+    /**
+     * 处理查询请求。
+     * 
+     * @param uri           查询的URI
+     * @param projection    查询的列
+     * @param selection     查询的条件
+     * @param selectionArgs 查询条件的参数
+     * @param sortOrder     排序方式
+     * @return 返回Cursor，表示查询结果
+     */
+    @Override
+    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
+        Cursor c = null;
+        SQLiteDatabase db = mHelper.getReadableDatabase();
+        String id = null;
+        
+        // 根据URI匹配码执行不同的查询操作
+        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: // 查询单个笔记
+                id = uri.getPathSegments().get(1);
+                c = db.query(TABLE.NOTE, projection, NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs, null, null, sortOrder);
+                break;
+            case URI_DATA: // 查询所有数据
+                c = db.query(TABLE.DATA, projection, selection, selectionArgs, null, null, sortOrder);
+                break;
+            case URI_DATA_ITEM: // 查询单个数据
+                id = uri.getPathSegments().get(1);
+                c = db.query(TABLE.DATA, projection, DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs, null, null, sortOrder);
+                break;
+            case URI_SEARCH: // 搜索笔记
+            case URI_SEARCH_SUGGEST: // 搜索建议
+                if (sortOrder != null || projection != null) {
+                    throw new IllegalArgumentException("do not specify sortOrder, selection, selectionArgs, or projection" + "with this query");
+                }
+                String searchString = null;
+                if (mMatcher.match(uri) == URI_SEARCH_SUGGEST) {
+                    if (uri.getPathSegments().size() > 1) {
+                        searchString = uri.getPathSegments().get(1);
+                    }
+                } else {
+                    searchString = uri.getQueryParameter("pattern");
+                }
+                if (TextUtils.isEmpty(searchString)) {
+                    return null;
+                }
+                try {
+                    searchString = String.format("%%%s%%", searchString); // 添加通配符进行模糊查询
+                    c = db.rawQuery(NOTES_SNIPPET_SEARCH_QUERY, new String[] { searchString });
+                } catch (IllegalStateException ex) {
+                    Log.e(TAG, "got exception: " + ex.toString());
+                }
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri); // 未知的URI类型
+        }
+        
+        // 如果Cursor不为空，设置通知URI，监听数据变化
+        if (c != null) {
+            c.setNotificationUri(getContext().getContentResolver(), uri);
+        }
+        return c;
+    }
+
+    /**
+     * 处理插入请求。
+     * 
+     * @param uri    插入的URI
+     * @param values 要插入的数据
+     * @return 返回新插入记录的URI
+     */
+    @Override
+    public Uri insert(Uri uri, ContentValues values) {
+        SQLiteDatabase db = mHelper.getWritableDatabase();
+        long dataId = 0, noteId = 0, insertedId = 0;
+
+        // 根据URI匹配码执行不同的插入操作
+        switch (mMatcher.match(uri)) {
+            case URI_NOTE: // 插入一条笔记
+                insertedId = noteId = db.insert(TABLE.NOTE, null, values);
+                break;
+            case URI_DATA: // 插入一条数据
+                if (values.containsKey(DataColumns.NOTE_ID)) {
+                    noteId = values.getAsLong(DataColumns.NOTE_ID);
+                } else {
+                    Log.d(TAG, "Wrong data format without note id:" + values.toString());
+                }
+                insertedId = dataId = db.insert(TABLE.DATA, null, values);
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri); // 未知的URI类型
+        }
+
+        // 通知数据改变
+        if (noteId > 0) {
+            getContext().getContentResolver().notifyChange(ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null);
+        }
+        if (dataId > 0) {
+            getContext().getContentResolver().notifyChange(ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId), null);
+        }
+        return ContentUris.withAppendedId(uri, insertedId); // 返回新记录的URI
+    }
+
+    /**
+     * 处理删除请求。
+     * 
+     * @param uri           删除的URI
+     * @param selection     删除的条件
+     * @param selectionArgs 删除条件的参数
+     * @return 返回删除的记录数
+     */
+    @Override
+    public int delete(Uri uri, String selection, String[] selectionArgs) {
+        int count = 0;
+        String id = null;
+        SQLiteDatabase db = mHelper.getWritableDatabase();
+        boolean deleteData = false;
+
+        // 根据URI匹配码执行不同的删除操作
+        switch (mMatcher.match(uri)) {
+            case URI_NOTE: // 删除笔记
+                selection = "(" + selection + ") AND " + NoteColumns.ID + ">0 ";
+                count = db.delete(TABLE.NOTE, selection, selectionArgs);
+                break;
+            case URI_NOTE_ITEM: // 删除单个笔记
+                id = uri.getPathSegments().get(1);
+                long noteId = Long.valueOf(id);
+                if (noteId <= 0) { // 如果笔记ID小于等于0，不允许删除
+                    break;
+                }
+                count = db.delete(TABLE.NOTE, NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
+                break;
+            case URI_DATA: // 删除数据
+                count = db.delete(TABLE.DATA, selection, selectionArgs);
+                deleteData = true;
+                break;
+            case URI_DATA_ITEM: // 删除单个数据
+                id = uri.getPathSegments().get(1);
+                count = db.delete(TABLE.DATA, DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
+                deleteData = true;
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri); // 未知的URI类型
+        }
+
+        // 如果删除成功，通知数据变化
+        if (count > 0) {
+            if (deleteData) {
+                getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
+            }
+            getContext().getContentResolver().notifyChange(uri, null);
+        }
+        return count;
+    }
+
+    /**
+     * 处理更新请求。
+     * 
+     * @param uri           更新的URI
+     * @param values        更新的内容
+     * @param selection     更新的条件
+     * @param selectionArgs 更新条件的参数
+     * @return 返回更新的记录数
+     */
+    @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;
+
+        // 根据URI匹配码执行不同的更新操作
+        switch (mMatcher.match(uri)) {
+            case URI_NOTE: // 更新笔记
+                increaseNoteVersion(-1, selection, selectionArgs); // 更新笔记版本
+                count = db.update(TABLE.NOTE, values, selection, selectionArgs);
+                break;
+            case URI_NOTE_ITEM: // 更新单个笔记
+                id = uri.getPathSegments().get(1);
+                increaseNoteVersion(Long.valueOf(id), selection, selectionArgs); // 更新指定笔记版本
+                count = db.update(TABLE.NOTE, values, NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
+                break;
+            case URI_DATA: // 更新数据
+                count = db.update(TABLE.DATA, values, selection, selectionArgs);
+                updateData = true;
+                break;
+            case URI_DATA_ITEM: // 更新单个数据
+                id = uri.getPathSegments().get(1);
+                count = db.update(TABLE.DATA, values, DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
+                updateData = true;
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri); // 未知的URI类型
+        }
+
+        // 如果更新成功，通知数据变化
+        if (count > 0) {
+            if (updateData) {
+                getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
+            }
+            getContext().getContentResolver().notifyChange(uri, null);
+        }
+        return count;
+    }
+
+    /**
+     * 辅助方法，解析选择条件。
+     * 
+     * @param selection 选择条件
+     * @return 返回解析后的选择条件
+     */
+    private String parseSelection(String selection) {
+        return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : "");
+    }
+
+    /**
+     * 更新笔记的版本号。
+     * 
+     * @param id            笔记ID
+     * @param selection     选择条件
+     * @param selectionArgs 选择条件参数
+     */
+    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 ");
+
+        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SQL更新版本
+        mHelper.getWritableDatabase().execSQL(sql.toString());
+    }
+
+    @Override
+    public String getType(Uri uri) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+}