xiangjiawei

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;
+        }
+    }
+}

src/Notes.java

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+/*
+ * 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");
+    }
+}

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");
+    }
+}

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;
+    }
+}