diff --git a/doc/王培鑫小米便签精读部分/Contact.java b/doc/王培鑫小米便签精读部分/Contact.java
new file mode 100644
index 0000000..a940a4a
--- /dev/null
+++ b/doc/王培鑫小米便签精读部分/Contact.java
@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)//存放联系人信息
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");//说明小米便签版本
+ * 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//小米便签的版权所有
+ *
+ * Unless required by applicable law or agreed to in writing, software//小米便签的条约说明
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.micode.notes.data;//包文件
+
+import android.content.Context;//调用android自带的类
+import android.database.Cursor;//从数据库中导入Cursor
+import android.provider.ContactsContract.CommonDataKinds.Phone;//获取联系人电话信息
+import android.provider.ContactsContract.Data;//存储联系人信息
+import android.telephony.PhoneNumberUtils;//格式化用户输入的电话号码
+import android.util.Log;//日志接口
+
+import java.util.HashMap;//存储联系人信息
+
+public class Contact {//联系人类
+    private static HashMap<String, String> sContactCache;//作为缓存，存储联系人信息
+    private static final String TAG = "Contact";//定义字符串常量
+
+    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 = '+')";//定义字符串，匹配联系人
+
+    public static String getContact(Context context, String phoneNumber) {//获取联系人
+        if(sContactCache == null) {
+            sContactCache = new HashMap<String, String>();//初始化联系人缓存表
+        }
+
+        if(sContactCache.containsKey(phoneNumber)) {
+            return sContactCache.get(phoneNumber);//在数据库中查找联系人信息
+        }
+
+        String selection = CALLER_ID_SELECTION.replace("+",
+                PhoneNumberUtils.toCallerIDMinMatch(phoneNumber));//将CALLER_ID_SELECTION的最后的+好替代为号码的后MIN_MATCH位
+        Cursor cursor = context.getContentResolver().query(//从数据库中读取数据
+                Data.CONTENT_URI,
+                new String [] { Phone.DISPLAY_NAME },//返回联系人姓名
+                selection,
+                new String[] { phoneNumber },
+                null);//判断查询结果，move ToFirst返回第一条
+
+        if (cursor != null && cursor.moveToFirst()) {//找到对应信息
+            try {
+                String name = cursor.getString(0);//获取联系人信息
+                sContactCache.put(phoneNumber, name);
+                return name;
+            } catch (IndexOutOfBoundsException e) {//出现异常
+                Log.e(TAG, " Cursor get string error " + e.toString());
+                return null;
+            } finally {//关闭数据库访问
+                cursor.close();
+            }
+        } else {
+            Log.d(TAG, "No contact matched with number:" + phoneNumber);//未匹配到该号码
+            return null;
+        }
+    }
+}
diff --git a/doc/王培鑫小米便签精读部分/GTaskASyncTask.java b/doc/王培鑫小米便签精读部分/GTaskASyncTask.java
new file mode 100644
index 0000000..46b6704
--- /dev/null
+++ b/doc/王培鑫小米便签精读部分/GTaskASyncTask.java
@@ -0,0 +1,123 @@
+
+/*
+ * 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.gtask.remote;//实现Gtask异步操作过程
+
+import android.app.Notification;//引用的包名
+import android.app.NotificationManager;
+import android.app.PendingIntent;
+import android.content.Context;
+import android.content.Intent;
+import android.os.AsyncTask;
+
+import net.micode.notes.R;//引入android自动生成的R类
+import net.micode.notes.ui.NotesListActivity;//自动生成的该程序包名下的R.java，专门用于管理二进制资源
+import net.micode.notes.ui.NotesPreferenceActivity;
+
+
+public class GTaskASyncTask extends AsyncTask<Void, String, Integer> {//异步任务类：任务同步和取消，显示同步任务的进程、通知和结果
+
+    private static int GTASK_SYNC_NOTIFICATION_ID = 5234235;//static int变量存储GTask同步通知的ID。
+
+    public interface OnCompleteListener {//初始化异步功能
+        void onComplete();
+    }
+
+    private Context mContext;//文本内容
+
+    private NotificationManager mNotifiManager;//对象： 通知管理器类的实例化
+
+    private GTaskManager mTaskManager;//实例化任务管理器
+
+    private OnCompleteListener mOnCompleteListener;//实例化是否完成的监听器
+
+    public GTaskASyncTask(Context context, OnCompleteListener listener) {// GTaskASyncTask类的构造函数
+        mContext = context;
+        mOnCompleteListener = listener;
+        mNotifiManager = (NotificationManager) mContext//getSystemService是Activity的一个方法，可根据传入的参数获得应服务的对象。这里以Context的NOTIFICATION_SERVICE为对象。
+                .getSystemService(Context.NOTIFICATION_SERVICE);//getSystemService是一种可根据传入的参数获得应服务的对象的端口函数。
+        mTaskManager = GTaskManager.getInstance();单例模式创建类的实例
+    }
+
+    public void cancelSync() {//取消同步
+        mTaskManager.cancelSync();//取消同步
+    }
+
+    public void publishProgess(String message) {//显示信息
+        publishProgress(new String[] {
+            message
+        });
+    }
+
+    private void showNotification(int tickerId, String content) {//显示通知
+        Notification notification = new Notification(R.drawable.notification, mContext//新建通知
+                .getString(tickerId), System.currentTimeMillis());
+        notification.defaults = Notification.DEFAULT_LIGHTS;
+        notification.flags = Notification.FLAG_AUTO_CANCEL;
+        PendingIntent pendingIntent;
+        if (tickerId != R.string.ticker_success) {//如果同步失败，就从系统取得一个用于启动NotesPreferenceActivity的PendingIntent对象。
+            pendingIntent = PendingIntent.getActivity(mContext, 0, new Intent(mContext,
+                    NotesPreferenceActivity.class), 0);//如果同步不成功，会从系统获取一个来启动NotesPreferenceActivity的对象
+
+        } else {// 若同步成功，则从系统中获得一个对象来启动NotesListActivity
+            pendingIntent = PendingIntent.getActivity(mContext, 0, new Intent(mContext,
+                    NotesListActivity.class), 0);
+        }
+        notification.setLatestEventInfo(mContext, mContext.getString(R.string.app_name), content,//设置最新事件信息
+                pendingIntent);
+        mNotifiManager.notify(GTASK_SYNC_NOTIFICATION_ID, notification);//通过NotificationManager对象的notify（）方法来执行一个notification的消息
+    }
+
+    @Override
+    protected Integer doInBackground(Void... unused) {//执行后台操作
+        publishProgess(mContext.getString(R.string.sync_progress_login, NotesPreferenceActivity
+                .getSyncAccountName(mContext)));
+        return mTaskManager.sync(mContext, this);//进行后台同步具体操作
+    }
+
+    @Override
+    protected void onProgressUpdate(String... progress) {//显示进度的更新
+        showNotification(R.string.ticker_syncing, progress[0]);
+        if (mContext instanceof GTaskSyncService) {//mContext是否在GTaskSyncService类中
+            ((GTaskSyncService) mContext).sendBroadcast(progress[0]);
+        }
+    }
+
+    @Override
+    protected void onPostExecute(Integer result) {//设置任务，比如在用户界面显示一个进度条
+        if (result == GTaskManager.STATE_SUCCESS) {//同步成功，显示相应的东西。
+            showNotification(R.string.ticker_success, mContext.getString(//若同步成功，则显示成功及展示出同步的账户
+                    R.string.success_sync_account, mTaskManager.getSyncAccount()));
+            NotesPreferenceActivity.setLastSyncTime(mContext, System.currentTimeMillis());//设置当前最新同步时间
+        } else if (result == GTaskManager.STATE_NETWORK_ERROR) {//如果网络错误则显示网络错误的通知
+            showNotification(R.string.ticker_fail, mContext.getString(R.string.error_sync_network));
+        } else if (result == GTaskManager.STATE_INTERNAL_ERROR) {//网络错误导致同步错误。
+            showNotification(R.string.ticker_fail, mContext.getString(R.string.error_sync_internal));
+        } else if (result == GTaskManager.STATE_SYNC_CANCELLED) {//如果同步被取消则显示其通知
+            showNotification(R.string.ticker_cancel, mContext
+                    .getString(R.string.error_sync_cancelled));
+        }
+        if (mOnCompleteListener != null) {//若监听器为空，则创建新进程
+            new Thread(new Runnable() {//创建新进程
+
+                public void run() {
+                    mOnCompleteListener.onComplete();//执行完后调用，返回主线程中
+                }
+            }).start();
+        }
+    }
+}
diff --git a/doc/王培鑫小米便签精读部分/GTaskManager.java b/doc/王培鑫小米便签精读部分/GTaskManager.java
new file mode 100644
index 0000000..c453b05
--- /dev/null
+++ b/doc/王培鑫小米便签精读部分/GTaskManager.java
@@ -0,0 +1,800 @@
+/*
+ * 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.gtask.remote;//实现同步功能的主函数
+
+import android.app.Activity;//在包里引用各种类
+import android.content.ContentResolver;//引用各种类
+import android.content.ContentUris;
+import android.content.ContentValues;
+import android.content.Context;
+import android.database.Cursor;
+import android.util.Log;
+
+import net.micode.notes.R;
+import net.micode.notes.data.Notes;
+import net.micode.notes.data.Notes.DataColumns;
+import net.micode.notes.data.Notes.NoteColumns;
+import net.micode.notes.gtask.data.MetaData;
+import net.micode.notes.gtask.data.Node;
+import net.micode.notes.gtask.data.SqlNote;
+import net.micode.notes.gtask.data.Task;
+import net.micode.notes.gtask.data.TaskList;
+import net.micode.notes.gtask.exception.ActionFailureException;
+import net.micode.notes.gtask.exception.NetworkFailureException;
+import net.micode.notes.tool.DataUtils;
+import net.micode.notes.tool.GTaskStringUtils;
+
+import org.json.JSONArray;
+import org.json.JSONException;
+import org.json.JSONObject;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.Map;
+
+
+public class GTaskManager {//声明一个类，类名称的命名规范：所有单词的首字母大写
+    private static final String TAG = GTaskManager.class.getSimpleName();// 定义了一系列静态变量来显示GTask当前的状态
+
+    public static final int STATE_SUCCESS = 0;
+
+    public static final int STATE_NETWORK_ERROR = 1;
+
+    public static final int STATE_INTERNAL_ERROR = 2;
+
+    public static final int STATE_SYNC_IN_PROGRESS = 3;
+
+    public static final int STATE_SYNC_CANCELLED = 4;//声明了5个静态变量来分别表示5种状态
+
+    private static GTaskManager mInstance = null;//private 定义一系列不可被外部的类访问的量
+
+    private Activity mActivity;
+
+    private Context mContext;
+
+    private ContentResolver mContentResolver;
+
+    private boolean mSyncing;
+
+    private boolean mCancelled;
+
+    private HashMap<String, TaskList> mGTaskListHashMap;
+
+    private HashMap<String, Node> mGTaskHashMap;
+
+    private HashMap<String, MetaData> mMetaHashMap;
+
+    private TaskList mMetaList;
+
+    private HashSet<Long> mLocalDeleteIdMap;
+
+    private HashMap<String, Long> mGidToNid;
+
+    private HashMap<Long, String> mNidToGid;
+
+    private GTaskManager() {//方法：类的构造函数，对其内部变量进行初始化
+        mSyncing = false;//正在同步标识，false代表未同步
+        mCancelled = false;
+        mGTaskListHashMap = new HashMap<String, TaskList>();//Hashmap的映射实现字符串到对象。
+        mGTaskHashMap = new HashMap<String, Node>();//创建一个节点表
+        mMetaHashMap = new HashMap<String, MetaData>();//创建一个删除本地ID的map
+        mMetaList = null;//创建一个删除本地ID的map
+        mLocalDeleteIdMap = new HashSet<Long>();
+        mGidToNid = new HashMap<String, Long>();//建立一个google id到节点id的映射
+        mNidToGid = new HashMap<Long, String>();
+    }
+
+    public static synchronized GTaskManager getInstance() {//用static synchronized控制类的所有实例的访问
+        if (mInstance == null) {
+            mInstance = new GTaskManager();
+        }
+        return mInstance;
+    }
+
+    public synchronized void setActivityContext(Activity activity) {//获取当前的操作并更新至GTask中
+        // used for getting authtoken
+        mActivity = activity;
+    }
+
+    public int sync(Context context, GTaskASyncTask asyncTask) {
+        if (mSyncing) {
+            Log.d(TAG, "Sync is in progress");
+            return STATE_SYNC_IN_PROGRESS;
+        }
+        mContext = context;
+        mContentResolver = mContext.getContentResolver();//对GTaskManager的属性进行更新
+        mSyncing = true;
+        mCancelled = false;
+        mGTaskListHashMap.clear();//对各种结构进行清空
+        mGTaskHashMap.clear();
+        mMetaHashMap.clear();
+        mLocalDeleteIdMap.clear();
+        mGidToNid.clear();
+        mNidToGid.clear();
+
+        try {//异常处理程序
+            GTaskClient client = GTaskClient.getInstance();//实例化一个GTask用户对象
+            client.resetUpdateArray();//重置更新操作。
+
+            // login google task
+            if (!mCancelled) {//代码块：登陆google task，如果mActivity登录不上则抛出一个异常
+                if (!client.login(mActivity)) {
+                    throw new NetworkFailureException("login google task failed");
+                }
+            }
+
+            // get the task list from google
+            asyncTask.publishProgess(mContext.getString(R.string.sync_progress_init_list));
+            initGTaskList();//调用下面自定义的方法，初始化GTaskList
+
+            // do content sync work
+            asyncTask.publishProgess(mContext.getString(R.string.sync_progress_syncing));
+            syncContent();//进行同步操作
+        } catch (NetworkFailureException e) {//处理各种异常
+            Log.e(TAG, e.toString());
+            return STATE_NETWORK_ERROR;
+        } catch (ActionFailureException e) {//操作未完成异常
+            Log.e(TAG, e.toString());
+            return STATE_INTERNAL_ERROR;
+        } catch (Exception e) {//内部错误异常
+            Log.e(TAG, e.toString());
+            e.printStackTrace();
+            return STATE_INTERNAL_ERROR;
+        } finally {//结束后清空环境。
+            mGTaskListHashMap.clear();//同步结束后清空环境
+            mGTaskHashMap.clear();
+            mMetaHashMap.clear();
+            mLocalDeleteIdMap.clear();
+            mGidToNid.clear();
+            mNidToGid.clear();
+            mSyncing = false;
+        }
+
+        return mCancelled ? STATE_SYNC_CANCELLED : STATE_SUCCESS;//若在同步时操作未取消，则返回同步成功，否则返回同步操作取消
+    }
+
+    private void initGTaskList() throws NetworkFailureException {//初始化任务列表，其实就是从Google获取任务列表。
+        if (mCancelled)//初始化任务列表，其实就是从Google获取任务列表。
+            return;
+        GTaskClient client = GTaskClient.getInstance();// 实例化一个GTask用户对象
+        try {//获取任务列表
+            JSONArray jsTaskLists = client.getTaskLists();//获取任务列表
+
+            // init meta list first
+            mMetaList = null;
+            for (int i = 0; i < jsTaskLists.length(); i++) {//对于获取的每一个任务串jsonarray
+                JSONObject object = jsTaskLists.getJSONObject(i);//获得任务串的每一个结点和id名字
+                String gid = object.getString(GTaskStringUtils.GTASK_JSON_ID);//获取它的id
+                String name = object.getString(GTaskStringUtils.GTASK_JSON_NAME);//获取它的名字
+
+                if (name
+                        .equals(GTaskStringUtils.MIUI_FOLDER_PREFFIX + GTaskStringUtils.FOLDER_META)) {//如果 name 等于 字符串 "[MIUI_Notes]" + "METADATA"，执行if语句块
+                    mMetaList = new TaskList();//新建数组，并为新建的数组设定内容
+                    mMetaList.setContentByRemoteJSON(object);
+
+                    // load meta data
+                    JSONArray jsMetas = client.getTaskList(gid);//读取元数据
+                    for (int j = 0; j < jsMetas.length(); j++) {//把jsMetas里的每一个有识别码的metaData都放到哈希表中
+                        object = (JSONObject) jsMetas.getJSONObject(j);
+                        MetaData metaData = new MetaData();
+                        metaData.setContentByRemoteJSON(object);
+                        if (metaData.isWorthSaving()) {//判断前面获取的元数据有无价值加入列表中
+                            mMetaList.addChildTask(metaData);
+                            if (metaData.getGid() != null) {//操作getGid：取得组识别码函数
+                                mMetaHashMap.put(metaData.getRelatedGid(), metaData);
+                            }
+                        }
+                    }
+                }
+            }
+
+            // create meta list if not existed
+            if (mMetaList == null) {//如果元数据列表不存在，则在客户端创建一个
+                mMetaList = new TaskList();
+                mMetaList.setName(GTaskStringUtils.MIUI_FOLDER_PREFFIX
+                        + GTaskStringUtils.FOLDER_META);
+                GTaskClient.getInstance().createTaskList(mMetaList);
+            }
+
+            // init task list
+            for (int i = 0; i < jsTaskLists.length(); i++) {//初始化任务列表
+                JSONObject object = jsTaskLists.getJSONObject(i);
+                String gid = object.getString(GTaskStringUtils.GTASK_JSON_ID);
+                String name = object.getString(GTaskStringUtils.GTASK_JSON_NAME);
+
+                if (name.startsWith(GTaskStringUtils.MIUI_FOLDER_PREFFIX)
+                        && !name.equals(GTaskStringUtils.MIUI_FOLDER_PREFFIX
+                                + GTaskStringUtils.FOLDER_META)) {
+                    TaskList tasklist = new TaskList();//创建一个新的任务列表
+                    tasklist.setContentByRemoteJSON(object);//对任务列表的内容进行设置
+                    mGTaskListHashMap.put(gid, tasklist);//对任务列表的内容进行设置
+                    mGTaskHashMap.put(gid, tasklist);
+
+                    // load tasks
+                    JSONArray jsTasks = client.getTaskList(gid);//获取任务id号
+                    for (int j = 0; j < jsTasks.length(); j++) {
+                        object = (JSONObject) jsTasks.getJSONObject(j);
+                        gid = object.getString(GTaskStringUtils.GTASK_JSON_ID);
+                        Task task = new Task();
+                        task.setContentByRemoteJSON(object);//设置任务内容
+                        if (task.isWorthSaving()) {//判断该任务有无价值保存
+                            task.setMetaInfo(mMetaHashMap.get(gid));
+                            tasklist.addChildTask(task);
+                            mGTaskHashMap.put(gid, task);
+                        }
+                    }
+                }
+            }
+        } catch (JSONException e) {//初始化时捕捉异常
+            Log.e(TAG, e.toString());//获取异常类型和异常详细消息
+            e.printStackTrace();
+            throw new ActionFailureException("initGTaskList: handing JSONObject failed");//抛出异常，提交 JSONObject 失败
+        }
+    }
+
+    private void syncContent() throws NetworkFailureException {//实现内容同步的操作
+        int syncType;
+        Cursor c = null;
+        String gid;
+        Node node;
+
+        mLocalDeleteIdMap.clear();
+
+        if (mCancelled) {//对于本地已删除的便签采取的动作
+            return;
+        }
+
+        // for local deleted note
+        try {//代码块：对本地要删除的节点进行操作
+            c = mContentResolver.query(Notes.CONTENT_NOTE_URI, SqlNote.PROJECTION_NOTE,
+                    "(type<>? AND parent_id=?)", new String[] {//定位要删除的节点位置
+                            String.valueOf(Notes.TYPE_SYSTEM), String.valueOf(Notes.ID_TRASH_FOLER)
+                    }, null);
+            if (c != null) {//代码块：若获取到的待删除便签不为空，则进行同步操作
+                while (c.moveToNext()) {// 通过while用指针遍历所有结点
+                    gid = c.getString(SqlNote.GTASK_ID_COLUMN);
+                    node = mGTaskHashMap.get(gid);
+                    if (node != null) {//节点非空则从哈希表里删除，并进行同步操作
+                        mGTaskHashMap.remove(gid);
+                        doContentSync(Node.SYNC_ACTION_DEL_REMOTE, node, c);
+                    }
+
+                    mLocalDeleteIdMap.add(c.getLong(SqlNote.ID_COLUMN));//在本地删除记录中添加这一项记录
+                }
+            } else {//若c结点为空，即寻找错误的时候，报错
+                Log.w(TAG, "failed to query trash folder");
+            }
+        } finally {//代码块：最后把c关闭并重置
+            if (c != null) {
+                c.close();
+                c = null;
+            }
+        }
+
+        // sync folder first
+        syncFolder();
+
+        // for note existing in database
+        try {//代码块：对已存在于数据库的便签进行同步
+            c = mContentResolver.query(Notes.CONTENT_NOTE_URI, SqlNote.PROJECTION_NOTE,
+                    "(type=? AND parent_id<>?)", new String[] {//c指针指向待操作的位置
+                            String.valueOf(Notes.TYPE_NOTE), String.valueOf(Notes.ID_TRASH_FOLER)
+                    }, NoteColumns.TYPE + " DESC");
+            if (c != null) {//query语句的用法
+                while (c.moveToNext()) {//遍历节点
+                    gid = c.getString(SqlNote.GTASK_ID_COLUMN);
+                    node = mGTaskHashMap.get(gid);//获取待操作的便签的节点
+                    if (node != null) {//节点不为空则删除gid，重新建立节点到gid的联系
+                        mGTaskHashMap.remove(gid);
+                        mGidToNid.put(gid, c.getLong(SqlNote.ID_COLUMN));//建立google id到节点id的映射
+                        mNidToGid.put(c.getLong(SqlNote.ID_COLUMN), gid);//建立Nid到Gid之间的映射表
+                        syncType = node.getSyncAction(c);
+                    } else {//若为空，先判断sqlnote的trim是否为0，是则确定同步方式为add_remote，否则为del_local
+                        if (c.getString(SqlNote.GTASK_ID_COLUMN).trim().length() == 0) {//若本地增加了内容，则远程也要增加内容
+                            // local add
+                            syncType = Node.SYNC_ACTION_ADD_REMOTE;// 远程增加内容
+                        } else {//若本地删除了内容，则远程也要删除内容应的gid
+                            // remote delete
+                            syncType = Node.SYNC_ACTION_DEL_LOCAL;//本地删除
+                        }
+                    }
+                    doContentSync(syncType, node, c);
+                }
+            } else {
+                Log.w(TAG, "failed to query existing note in database");//查询失败时在日志中写回错误信息
+            }
+
+        } finally {//在最后关闭c并重置
+            if (c != null) {
+                c.close();
+                c = null;
+            }
+        }
+
+        // go through remaining items
+        Iterator<Map.Entry<String, Node>> iter = mGTaskHashMap.entrySet().iterator();//扫描剩下的项目，逐个进行同步
+        while (iter.hasNext()) {//迭代
+            Map.Entry<String, Node> entry = iter.next();
+            node = entry.getValue();
+            doContentSync(Node.SYNC_ACTION_ADD_LOCAL, node, null);
+        }
+
+        // mCancelled can be set by another thread, so we neet to check one by
+        // one
+        // clear local delete table
+        if (!mCancelled) {//终止标识有可能被其他进程改变，因此需要一个个进行检查
+            if (!DataUtils.batchDeleteNotes(mContentResolver, mLocalDeleteIdMap)) {
+                throw new ActionFailureException("failed to batch-delete local deleted notes");//终止标识有可能被其他线程改变
+            }
+        }
+
+        // refresh local sync id
+        if (!mCancelled) {//更新同步表
+            GTaskClient.getInstance().commitUpdate();
+            refreshLocalSyncId();
+        }
+
+    }
+
+    private void syncFolder() throws NetworkFailureException {//同步文件夹
+        Cursor c = null;
+        String gid;
+        Node node;
+        int syncType;
+
+        if (mCancelled) {//判断是否取消该操作
+            return;
+        }
+
+        // for root folder
+        try {//对于根文件夹
+            c = mContentResolver.query(ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI,
+                    Notes.ID_ROOT_FOLDER), SqlNote.PROJECTION_NOTE, null, null, null);
+            if (c != null) {
+                c.moveToNext();
+                gid = c.getString(SqlNote.GTASK_ID_COLUMN);//获取指针指向内容对应的gid
+                node = mGTaskHashMap.get(gid);
+                if (node != null) {// 获取gid所代表的节点
+                    mGTaskHashMap.remove(gid);
+                    mGidToNid.put(gid, (long) Notes.ID_ROOT_FOLDER);//将该节点的gid到nid的映射加入映射表
+                    mNidToGid.put((long) Notes.ID_ROOT_FOLDER, gid);
+                    // for system folder, only update remote name if necessary
+                    if (!node.getName().equals(//若当前访问的文件夹是系统文件夹则只需要更新
+                            GTaskStringUtils.MIUI_FOLDER_PREFFIX + GTaskStringUtils.FOLDER_DEFAULT))
+                        doContentSync(Node.SYNC_ACTION_UPDATE_REMOTE, node, c);
+                } else {
+                    doContentSync(Node.SYNC_ACTION_ADD_REMOTE, node, c);//若非系统文件夹则在远程进行增加节点操作
+                }
+            } else {
+                Log.w(TAG, "failed to query root folder");//警告，询问根目录文件夹失败
+            }
+        } finally {//结束操作之后，最后将指针关闭，并将指针置空。方法与之前相同
+            if (c != null) {
+                c.close();
+                c = null;
+            }
+        }
+
+        // for call-note folder
+        try {
+            c = mContentResolver.query(Notes.CONTENT_NOTE_URI, SqlNote.PROJECTION_NOTE, "(_id=?)",//使指针指向文件夹的位置
+                    new String[] {
+                        String.valueOf(Notes.ID_CALL_RECORD_FOLDER)//添加MIUI文件前缀
+                    }, null);
+            if (c != null) {
+                if (c.moveToNext()) {
+                    gid = c.getString(SqlNote.GTASK_ID_COLUMN);//获取指针指向内容对应的gid
+                    node = mGTaskHashMap.get(gid);
+                    if (node != null) {
+                        mGTaskHashMap.remove(gid);
+                        mGidToNid.put(gid, (long) Notes.ID_CALL_RECORD_FOLDER);//将该节点的gid到nid的映射加入映射表
+                        mNidToGid.put((long) Notes.ID_CALL_RECORD_FOLDER, gid);
+                        // for system folder, only update remote name if
+                        // necessary
+                        if (!node.getName().equals(//若当前访问的文件夹是系统文件夹则只需要更新
+                                GTaskStringUtils.MIUI_FOLDER_PREFFIX
+                                        + GTaskStringUtils.FOLDER_CALL_NOTE))
+                            doContentSync(Node.SYNC_ACTION_UPDATE_REMOTE, node, c);
+                    } else {
+                        doContentSync(Node.SYNC_ACTION_ADD_REMOTE, node, c);//若非系统文件夹则在远程进行增加节点操作
+                    }
+                }
+            } else {
+                Log.w(TAG, "failed to query call note folder");//警告，询问通讯便签文件夹失败
+            }
+        } finally {
+            if (c != null) {//代码块：结束操作之后，将指针指向内容关闭并将指针置空
+                c.close();
+                c = null;
+            }
+        }
+
+        // for local existing folders
+        try {//对于本地已存在的文件的操作
+            c = mContentResolver.query(Notes.CONTENT_NOTE_URI, SqlNote.PROJECTION_NOTE,
+                    "(type=? AND parent_id<>?)", new String[] {
+                            String.valueOf(Notes.TYPE_FOLDER), String.valueOf(Notes.ID_TRASH_FOLER)
+                    }, NoteColumns.TYPE + " DESC");
+            if (c != null) {
+                while (c.moveToNext()) {//使指针遍历所有的文件夹
+                    gid = c.getString(SqlNote.GTASK_ID_COLUMN);
+                    node = mGTaskHashMap.get(gid);
+                    if (node != null) {
+                        mGTaskHashMap.remove(gid);
+                        mGidToNid.put(gid, c.getLong(SqlNote.ID_COLUMN));
+                        mNidToGid.put(c.getLong(SqlNote.ID_COLUMN), gid);
+                        syncType = node.getSyncAction(c);
+                    } else {//更新同步类型
+                        if (c.getString(SqlNote.GTASK_ID_COLUMN).trim().length() == 0) {
+                            // local add
+                            syncType = Node.SYNC_ACTION_ADD_REMOTE;
+                        } else {//若远程删除了内容，则本地也要删除内容
+                            // remote delete
+                            syncType = Node.SYNC_ACTION_DEL_LOCAL;
+                        }
+                    }
+                    doContentSync(syncType, node, c);//进行同步操作
+                }
+            } else {
+                Log.w(TAG, "failed to query existing folder");
+            }
+        } finally {//代码块：结束操作之后，将指针指向内容关闭并将指针置空
+            if (c != null) {
+                c.close();
+                c = null;
+            }
+        }
+
+        // for remote add folders
+        Iterator<Map.Entry<String, TaskList>> iter = mGTaskListHashMap.entrySet().iterator();//对于在远程增添的内容，将其在本地同步
+        while (iter.hasNext()) {//使用迭代器对远程增添的内容进行遍历
+            Map.Entry<String, TaskList> entry = iter.next();
+            gid = entry.getKey();
+            node = entry.getValue();
+            if (mGTaskHashMap.containsKey(gid)) {//获取gid对应的节点
+                mGTaskHashMap.remove(gid);
+                doContentSync(Node.SYNC_ACTION_ADD_LOCAL, node, null);
+            }
+        }
+
+        if (!mCancelled)
+            GTaskClient.getInstance().commitUpdate();//如果没有取消，在GTsk的客户端进行实例的提交更新
+    }
+
+    private void doContentSync(int syncType, Node node, Cursor c) throws NetworkFailureException {//内容同步
+        if (mCancelled) {//如果已经取消同步，直接返回
+            return;
+        }
+
+        MetaData meta;
+        switch (syncType) {//根据同步类型选择操作
+            case Node.SYNC_ACTION_ADD_LOCAL:
+                addLocalNode(node);
+                break;
+            case Node.SYNC_ACTION_ADD_REMOTE://远程添加
+                addRemoteNode(node, c);
+                break;
+            case Node.SYNC_ACTION_DEL_LOCAL://远程删除
+                meta = mMetaHashMap.get(c.getString(SqlNote.GTASK_ID_COLUMN));
+                if (meta != null) {
+                    GTaskClient.getInstance().deleteNode(meta);
+                }
+                mLocalDeleteIdMap.add(c.getLong(SqlNote.ID_COLUMN));
+                break;
+            case Node.SYNC_ACTION_DEL_REMOTE:
+                meta = mMetaHashMap.get(node.getGid());
+                if (meta != null) {
+                    GTaskClient.getInstance().deleteNode(meta);
+                }
+                GTaskClient.getInstance().deleteNode(node);
+                break;
+            case Node.SYNC_ACTION_UPDATE_LOCAL://更新远程数据
+                updateLocalNode(node, c);
+                break;
+            case Node.SYNC_ACTION_UPDATE_REMOTE:
+                updateRemoteNode(node, c);
+                break;
+            case Node.SYNC_ACTION_UPDATE_CONFLICT://这个case是更新冲突
+                // merging both modifications maybe a good idea
+                // right now just use local update simply
+                updateRemoteNode(node, c);
+                break;
+            case Node.SYNC_ACTION_NONE://空操作
+                break;
+            case Node.SYNC_ACTION_ERROR://操作错误
+            default:
+                throw new ActionFailureException("unkown sync action type");//抛出异常，未知的同步行为类型
+        }
+    }
+
+    private void addLocalNode(Node node) throws NetworkFailureException {//添加本地节点
+        if (mCancelled) {
+            return;
+        }
+
+        SqlNote sqlNote;
+        if (node instanceof TaskList) {//若待增添节点为任务列表中的节点，进一步操作
+            if (node.getName().equals(//根目录
+                    GTaskStringUtils.MIUI_FOLDER_PREFFIX + GTaskStringUtils.FOLDER_DEFAULT)) {
+                sqlNote = new SqlNote(mContext, Notes.ID_ROOT_FOLDER);
+            } else if (node.getName().equals(//判断是否在存电话的文件夹里
+                    GTaskStringUtils.MIUI_FOLDER_PREFFIX + GTaskStringUtils.FOLDER_CALL_NOTE)) {
+                sqlNote = new SqlNote(mContext, Notes.ID_CALL_RECORD_FOLDER);
+            } else {//若没有存放的文件夹，则将其放在根文件夹中
+                sqlNote = new SqlNote(mContext);
+                sqlNote.setContent(node.getLocalJSONFromContent());
+                sqlNote.setParentId(Notes.ID_ROOT_FOLDER);
+            }
+        } else {//若待增添节点不是任务列表中的节点，进一步操作
+            sqlNote = new SqlNote(mContext);
+            JSONObject js = node.getLocalJSONFromContent();
+            try {//异常判断
+                if (js.has(GTaskStringUtils.META_HEAD_NOTE)) {
+                    JSONObject note = js.getJSONObject(GTaskStringUtils.META_HEAD_NOTE);//获取对应便签的jsonobject对象
+                    if (note.has(NoteColumns.ID)) {//判断便签中是否有条目
+                        long id = note.getLong(NoteColumns.ID);
+                        if (DataUtils.existInNoteDatabase(mContentResolver, id)) {//若便签条目的id已无效，在便签中将其删除
+                            // the id is not available, have to create a new one
+                            note.remove(NoteColumns.ID);
+                        }
+                    }
+                }
+
+                if (js.has(GTaskStringUtils.META_HEAD_DATA)) {//以下为判断便签中的数据条目
+                    JSONArray dataArray = js.getJSONArray(GTaskStringUtils.META_HEAD_DATA);
+                    for (int i = 0; i < dataArray.length(); i++) {//依次删除存在的data的ID
+                        JSONObject data = dataArray.getJSONObject(i);
+                        if (data.has(DataColumns.ID)) {
+                            long dataId = data.getLong(DataColumns.ID);
+                            if (DataUtils.existInDataDatabase(mContentResolver, dataId)) {
+                                // the data id is not available, have to create
+                                // a new one
+                                data.remove(DataColumns.ID);
+                            }
+                        }
+                    }
+
+                }
+            } catch (JSONException e) {//对于异常进行处理
+                Log.w(TAG, e.toString());//获取异常类型和异常详细消息
+                e.printStackTrace();
+            }
+            sqlNote.setContent(js);//将之前的操作获取到的js更新至该节点中
+
+            Long parentId = mGidToNid.get(((Task) node).getParent().getGid());//找到父任务的ID号，并作为sqlNote的父任务的ID，没有父任务则报错
+            if (parentId == null) {//当不能找到该任务上一级的id时报错
+                Log.e(TAG, "cannot find task's parent id locally");
+                throw new ActionFailureException("cannot add local node");
+            }
+            sqlNote.setParentId(parentId.longValue());
+        }
+
+        // create the local node
+        sqlNote.setGtaskId(node.getGid());//用getGid函数获取node节点的Gid，用于设置本地Gtask的ID
+        sqlNote.commit(false);//更新本地便签
+
+        // update gid-nid mapping
+        mGidToNid.put(node.getGid(), sqlNote.getId());//更新gid与nid的映射表
+        mNidToGid.put(sqlNote.getId(), node.getGid());
+
+        // update meta
+        updateRemoteMeta(node.getGid(), sqlNote);//更新远程的数据
+    }
+
+    private void updateLocalNode(Node node, Cursor c) throws NetworkFailureException {//更新远程的数据
+        if (mCancelled) {//如果正在取消同步，直接返回
+            return;
+        }
+
+        SqlNote sqlNote;
+        // update the note locally
+        sqlNote = new SqlNote(mContext, c);//在指针指向处创建一个新的节点
+        sqlNote.setContent(node.getLocalJSONFromContent());//利用待更新节点中的内容对数据库节点进行设置
+
+        Long parentId = (node instanceof Task) ? mGidToNid.get(((Task) node).getParent().getGid())//设置父任务的ID
+                : new Long(Notes.ID_ROOT_FOLDER);
+        if (parentId == null) {//当不能找到该任务上一级的id时报错
+            Log.e(TAG, "cannot find task's parent id locally");
+            throw new ActionFailureException("cannot update local node");
+        }
+        sqlNote.setParentId(parentId.longValue());//设置该任务节点上一级的id 
+        sqlNote.commit(true);
+
+        // update meta info
+        updateRemoteMeta(node.getGid(), sqlNote);//更新远程的节点信息
+    }
+
+    private void addRemoteNode(Node node, Cursor c) throws NetworkFailureException {//添加远程节点
+        if (mCancelled) {//如果正在取消同步，直接返回
+            return;
+        }
+
+        SqlNote sqlNote = new SqlNote(mContext, c);//新建一个sql节点并将内容存储进Node中
+        Node n;
+
+        // update remotely
+        if (sqlNote.isNoteType()) {//若待增添的节点为任务节点，进一步操作
+            Task task = new Task();
+            task.setContentByLocalJSON(sqlNote.getContent());
+
+            String parentGid = mNidToGid.get(sqlNote.getParentId());//当不能找到该任务上一级的id时报错
+            if (parentGid == null) {
+                Log.e(TAG, "cannot find task's parent tasklist");
+                throw new ActionFailureException("cannot add remote task");
+            }
+            mGTaskListHashMap.get(parentGid).addChildTask(task);
+
+            GTaskClient.getInstance().createTask(task);
+            n = (Node) task;
+
+            // add meta
+            updateRemoteMeta(task.getGid(), sqlNote);
+        } else {
+            TaskList tasklist = null;
+
+            // we need to skip folder if it has already existed
+            String folderName = GTaskStringUtils.MIUI_FOLDER_PREFFIX;
+            if (sqlNote.getId() == Notes.ID_ROOT_FOLDER)//按照文件夹的形式进行命名
+                folderName += GTaskStringUtils.FOLDER_DEFAULT;
+            else if (sqlNote.getId() == Notes.ID_CALL_RECORD_FOLDER)
+                folderName += GTaskStringUtils.FOLDER_CALL_NOTE;//若为电话号码便签文件夹则按电话号码便签命名
+            else
+                folderName += sqlNote.getSnippet();
+
+            Iterator<Map.Entry<String, TaskList>> iter = mGTaskListHashMap.entrySet().iterator();//使用iterator作为map接口，对map进行遍历
+            while (iter.hasNext()) {//iterator迭代器，通过统一的接口迭代所有的map元素
+                Map.Entry<String, TaskList> entry = iter.next();
+                String gid = entry.getKey();
+                TaskList list = entry.getValue();
+
+                if (list.getName().equals(folderName)) {
+                    tasklist = list;
+                    if (mGTaskHashMap.containsKey(gid)) {
+                        mGTaskHashMap.remove(gid);
+                    }
+                    break;
+                }
+            }
+
+            // no match we can add now
+            if (tasklist == null) {//若找不到任务列表，则创建一个新的任务列表
+                tasklist = new TaskList();
+                tasklist.setContentByLocalJSON(sqlNote.getContent());
+                GTaskClient.getInstance().createTaskList(tasklist);
+                mGTaskListHashMap.put(tasklist.getGid(), tasklist);
+            }
+            n = (Node) tasklist;
+        }
+
+        // update local note
+        sqlNote.setGtaskId(n.getGid());//更新本地节点
+        sqlNote.commit(false);
+        sqlNote.resetLocalModified();
+        sqlNote.commit(true);
+
+        // gid-id mapping
+        mGidToNid.put(n.getGid(), sqlNote.getId());//更新gid与nid的映射表
+        mNidToGid.put(sqlNote.getId(), n.getGid());
+    }
+
+    private void updateRemoteNode(Node node, Cursor c) throws NetworkFailureException {//更新远程节点
+        if (mCancelled) {//如果正在取消同步，直接返回
+            return;
+        }
+
+        SqlNote sqlNote = new SqlNote(mContext, c);//在指针指向处创建一个新的节点
+
+        // update remotely
+        node.setContentByLocalJSON(sqlNote.getContent());//远程更新
+        GTaskClient.getInstance().addUpdateNode(node);//更新节点数据
+
+        // update meta
+        updateRemoteMeta(node.getGid(), sqlNote);//更新数据
+
+        // move task if necessary
+        if (sqlNote.isNoteType()) {//判断节点类型是否符合要求
+            Task task = (Task) node;
+            TaskList preParentList = task.getParent();
+
+            String curParentGid = mNidToGid.get(sqlNote.getParentId());
+            if (curParentGid == null) {//找不到当前任务的上一级任务列表，报错
+                Log.e(TAG, "cannot find task's parent tasklist");
+                throw new ActionFailureException("cannot update remote task");
+            }
+            TaskList curParentList = mGTaskListHashMap.get(curParentGid);
+
+            if (preParentList != curParentList) {//若两个上一级任务列表不一致，进行任务的移动，从之前的任务列表中移动到该列表中
+                preParentList.removeChildTask(task);
+                curParentList.addChildTask(task);
+                GTaskClient.getInstance().moveTask(task, preParentList, curParentList);
+            }
+        }
+
+        // clear local modified flag
+        sqlNote.resetLocalModified();//清除本地的modified flag
+        sqlNote.commit(true);
+    }
+
+    private void updateRemoteMeta(String gid, SqlNote sqlNote) throws NetworkFailureException {//更新远程的元数据节点
+        if (sqlNote != null && sqlNote.isNoteType()) {//判断节点类型是否符合，类型符合时才进行更新操作
+            MetaData metaData = mMetaHashMap.get(gid);
+            if (metaData != null) {//若元数据组为空，则创建一个新的元数据组
+                metaData.setMeta(gid, sqlNote.getContent());
+                GTaskClient.getInstance().addUpdateNode(metaData);
+            } else {//若元数据组不为空，则进行更新
+                metaData = new MetaData();
+                metaData.setMeta(gid, sqlNote.getContent());
+                mMetaList.addChildTask(metaData);
+                mMetaHashMap.put(gid, metaData);
+                GTaskClient.getInstance().createTask(metaData);
+            }
+        }
+    }
+
+    private void refreshLocalSyncId() throws NetworkFailureException {//刷新本地便签id，从远程同步
+        if (mCancelled) {
+            return;
+        }
+
+        // get the latest gtask list
+        mGTaskHashMap.clear();//获取最新的任务列表
+        mGTaskListHashMap.clear();
+        mMetaHashMap.clear();
+        initGTaskList();
+
+        Cursor c = null;
+        try {
+            c = mContentResolver.query(Notes.CONTENT_NOTE_URI, SqlNote.PROJECTION_NOTE,
+                    "(type<>? AND parent_id<>?)", new String[] {//c作为光标定位，用query进行查询
+                            String.valueOf(Notes.TYPE_SYSTEM), String.valueOf(Notes.ID_TRASH_FOLER)
+                    }, NoteColumns.TYPE + " DESC");
+            if (c != null) {
+                while (c.moveToNext()) {//用迭代器不断从GTask的哈希表中删除node节点，设置新的content和新的resolcer并更新
+                    String gid = c.getString(SqlNote.GTASK_ID_COLUMN);
+                    Node node = mGTaskHashMap.get(gid);
+                    if (node != null) {
+                        mGTaskHashMap.remove(gid);
+                        ContentValues values = new ContentValues();
+                        values.put(NoteColumns.SYNC_ID, node.getLastModified());//在ContentValues中创建键值对。准备通过contentResolver写入数据
+                        mContentResolver.update(ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI,
+                                c.getLong(SqlNote.ID_COLUMN)), values, null, null);//进行更新操作
+                    } else {//若发现节点为空则报错
+                        Log.e(TAG, "something is missed");
+                        throw new ActionFailureException(
+                                "some local items don't have gid after sync");
+                    }
+                }
+            } else {
+                Log.w(TAG, "failed to query local note to refresh sync id");
+            }
+        } finally {//结束操作之后，将指针指向内容关闭并将指针置空
+            if (c != null) {
+                c.close();
+                c = null;
+            }
+        }
+    }
+
+    public String getSyncAccount() {//获取同步帐户
+        return GTaskClient.getInstance().getSyncAccount().name;
+    }
+
+    public void cancelSync() {//取消同步，置mCancelled为true
+        mCancelled = true;
+    }
+}
diff --git a/doc/王培鑫小米便签精读部分/GTaskSyncService.java b/doc/王培鑫小米便签精读部分/GTaskSyncService.java
new file mode 100644
index 0000000..66f7780
--- /dev/null
+++ b/doc/王培鑫小米便签精读部分/GTaskSyncService.java
@@ -0,0 +1,128 @@
+/*
+ * 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.gtask.remote;//包名
+
+import android.app.Activity;//以下几行都是引用基于数据库服务的类
+import android.app.Service;
+import android.content.Context;
+import android.content.Intent;
+import android.os.Bundle;
+import android.os.IBinder;
+
+public class GTaskSyncService extends Service {// 类：由Service组件扩展而来，作用是提供GTask的同步服务
+    public final static String ACTION_STRING_NAME = "sync_action_type";//定义一系列静态变量
+
+    public final static int ACTION_START_SYNC = 0;
+
+    public final static int ACTION_CANCEL_SYNC = 1;
+
+    public final static int ACTION_INVALID = 2;//用数字0、1、2分别表示开始同步、取消同步、同步无效
+
+    public final static String GTASK_SERVICE_BROADCAST_NAME = "net.micode.notes.gtask.remote.gtask_sync_service";//广播名称
+
+    public final static String GTASK_SERVICE_BROADCAST_IS_SYNCING = "isSyncing";//表示广播正在同步
+
+    public final static String GTASK_SERVICE_BROADCAST_PROGRESS_MSG = "progressMsg";//进程消息
+
+    private static GTaskASyncTask mSyncTask = null;
+
+    private static String mSyncProgress = "";
+
+    private void startSync() {//开始同步
+        if (mSyncTask == null) {
+            mSyncTask = new GTaskASyncTask(this, new GTaskASyncTask.OnCompleteListener() {
+                public void onComplete() {//实现了在GTaskASyncTask类中定义的接口onComplete( )
+                    mSyncTask = null;
+                    sendBroadcast("");
+                    stopSelf();
+                }
+            });
+            sendBroadcast("");
+            mSyncTask.execute();//调用同步执行的函数
+        }
+    }
+
+    private void cancelSync() {//取消同步
+        if (mSyncTask != null) {
+            mSyncTask.cancelSync();
+        }
+    }
+
+    @Override
+    public void onCreate() {//初始化一个service
+        mSyncTask = null;
+    }
+
+    @Override
+    public int onStartCommand(Intent intent, int flags, int startId) {//告诉系统如何重启服务，如判断是否异常终止后重新启动，在何种情况下异常终止等。
+        Bundle bundle = intent.getExtras();
+        if (bundle != null && bundle.containsKey(ACTION_STRING_NAME)) {//判断当前的同步状态，根据开始或取消，执行对应操作
+            switch (bundle.getInt(ACTION_STRING_NAME, ACTION_INVALID)) {
+                case ACTION_START_SYNC:
+                    startSync();
+                    break;
+                case ACTION_CANCEL_SYNC:
+                    cancelSync();
+                    break;
+                default:
+                    break;
+            }
+            return START_STICKY;
+        }
+        return super.onStartCommand(intent, flags, startId);//调用父类的函数
+    }
+
+    @Override
+    public void onLowMemory() {//广播信息msg
+        if (mSyncTask != null) {
+            mSyncTask.cancelSync();
+        }
+    }
+
+    public IBinder onBind(Intent intent) {//service服务中的绑定操作
+        return null;
+    }
+
+    public void sendBroadcast(String msg) {//发送广播内容
+        mSyncProgress = msg;
+        Intent intent = new Intent(GTASK_SERVICE_BROADCAST_NAME);
+        intent.putExtra(GTASK_SERVICE_BROADCAST_IS_SYNCING, mSyncTask != null);
+        intent.putExtra(GTASK_SERVICE_BROADCAST_PROGRESS_MSG, msg);
+        sendBroadcast(intent);//发送这个通知
+    }
+
+    public static void startSync(Activity activity) {//开始同步
+        GTaskManager.getInstance().setActivityContext(activity);
+        Intent intent = new Intent(activity, GTaskSyncService.class);
+        intent.putExtra(GTaskSyncService.ACTION_STRING_NAME, GTaskSyncService.ACTION_START_SYNC);
+        activity.startService(intent);
+    }
+
+    public static void cancelSync(Context context) {//取消同步
+        Intent intent = new Intent(context, GTaskSyncService.class);
+        intent.putExtra(GTaskSyncService.ACTION_STRING_NAME, GTaskSyncService.ACTION_CANCEL_SYNC);
+        context.startService(intent);
+    }
+
+    public static boolean isSyncing() {//判断当前是否处于同步状态
+        return mSyncTask != null;
+    }
+
+    public static String getProgressString() {//返回当前同步状态
+        return mSyncProgress;
+    }
+}
diff --git a/doc/王培鑫小米便签精读部分/Notes.java b/doc/王培鑫小米便签精读部分/Notes.java
new file mode 100644
index 0000000..830b041
--- /dev/null
+++ b/doc/王培鑫小米便签精读部分/Notes.java
@@ -0,0 +1,279 @@
+/*
+ * 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//许可说明
+ * 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;// 表明包文件归属
+
+import android.net.Uri;//引用url
+public class Notes {//Notes类，在类中定义了了许多常量
+    public static final String AUTHORITY = "micode_notes";
+    public static final String TAG = "Notes";//APP名称
+    public static final int TYPE_NOTE     = 0;
+    public static final int TYPE_FOLDER   = 1;
+    public static final int TYPE_SYSTEM   = 2;
+
+    /**
+     * Following IDs are system folders' identifiers//下列标识为默认文件夹、临时文件夹、通话记录等
+     * {@link Notes#ID_ROOT_FOLDER } is default folder
+     * {@link Notes#ID_TEMPARAY_FOLDER } is for notes belonging no folder
+     * {@link Notes#ID_CALL_RECORD_FOLDER} is to store call records
+     */
+    public static final int ID_ROOT_FOLDER = 0;// 根目录
+    public static final int ID_TEMPARAY_FOLDER = -1;//临时文件夹
+    public static final int ID_CALL_RECORD_FOLDER = -2;//背景
+    public static final int ID_TRASH_FOLER = -3;//回收站文件夹
+
+    public static final String INTENT_EXTRA_ALERT_DATE = "net.micode.notes.alert_date";//文件夹编号
+    public static final String INTENT_EXTRA_BACKGROUND_ID = "net.micode.notes.background_color_id";//背景颜色
+    public static final String INTENT_EXTRA_WIDGET_ID = "net.micode.notes.widget_id";//桌面插件
+    public static final String INTENT_EXTRA_WIDGET_TYPE = "net.micode.notes.widget_type";// 大号桌面插件
+    public static final String INTENT_EXTRA_FOLDER_ID = "net.micode.notes.folder_id";//创建text note的存放地址
+    public static final String INTENT_EXTRA_CALL_DATE = "net.micode.notes.call_date";//定义call_data的ID
+
+    public static final int TYPE_WIDGET_INVALIDE      = -1;//定义查询便签和文件夹的指针
+    public static final int TYPE_WIDGET_2X            = 0;//定义查找数据的指针
+    public static final int TYPE_WIDGET_4X            = 1;// 定义桌面挂件的属性
+
+    public static class DataConstants {//DataContants类：存放textnotes和callnotes地址
+        public static final String NOTE = TextNote.CONTENT_ITEM_TYPE;
+        public static final String CALL_NOTE = CallNote.CONTENT_ITEM_TYPE;
+    }
+
+    /**
+     * Uri to query all notes and folders
+     */
+    public static final Uri CONTENT_NOTE_URI = Uri.parse("content://" + AUTHORITY + "/note");// URI常量，方便进行系统查询
+
+    /**
+     * Uri to query data
+     */
+    public static final Uri CONTENT_DATA_URI = Uri.parse("content://" + AUTHORITY + "/data");//通过uri查询数据
+
+    public interface NoteColumns {//定义NoteColumns的常量,用于后面创建数据库的表头
+        /**
+         * The unique ID for a row//主键
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String ID = "_id";//每一行的ID
+
+        /**
+         * The parent's id for note or folder
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String PARENT_ID = "parent_id";
+
+        /**
+         * Created data for note or folder//创建一个属于note或者folder的数据
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String CREATED_DATE = "created_date";//创建日期
+
+        /**
+         * Latest modified date
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String MODIFIED_DATE = "modified_date";// 更改时间
+
+
+        /**
+         * Alert date
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String ALERTED_DATE = "alert_date";
+
+        /**
+         * Folder's name or text content of note//文件夹名字或者文件内容
+         * <P> Type: TEXT </P>
+         */
+        public static final String SNIPPET = "snippet";//文件夹的名字或者便签内容
+
+        /**
+         * Note's widget id// note小物件id
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String WIDGET_ID = "widget_id";//小部件ID
+
+        /**
+         * Note's widget type//便签页数
+         * <P> Type: INTEGER (long) </P>//note小物件类型
+         */
+        public static final String WIDGET_TYPE = "widget_type";//小部件类型
+
+        /**
+         * Note's background color's id//便签背景颜色
+         * <P> Type: INTEGER (long) </P>//note背景颜色id
+         */
+        public static final String BG_COLOR_ID = "bg_color_id";//背景颜色ID
+
+        /**
+         * For text note, it doesn't has attachment, for multi-media
+         * note, it has at least one attachment
+         * <P> Type: INTEGER </P>//对于文字note，它没有附件，对于多个Note，它至少有一个附件
+         */
+        public static final String HAS_ATTACHMENT = "has_attachment";//是否有附件
+
+        /**
+         * Folder's count of notes
+         * <P> Type: INTEGER (long) </P>//文件夹内有多少个note
+         */
+        public static final String NOTES_COUNT = "notes_count";//文件夹中的便签数量
+
+        /**
+         * The file type: folder or note//文件类型:folder 或者 note
+         * <P> Type: INTEGER </P>
+         */
+        public static final String TYPE = "type";//是文件夹还是便签
+
+        /**
+         * The last sync id
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String SYNC_ID = "sync_id";
+
+        /**
+         * Sign to indicate local modified or not
+         * <P> Type: INTEGER </P>
+         */
+        public static final String LOCAL_MODIFIED = "local_modified";//标识是否本地修改
+
+        /**
+         * Original parent id before moving into temporary folder
+         * <P> Type : INTEGER </P>
+         */
+        public static final String ORIGIN_PARENT_ID = "origin_parent_id";//移动到临时文件夹之前的父文件夹
+
+        /**
+         * The gtask id
+         * <P> Type : TEXT </P>
+         */
+        public static final String GTASK_ID = "gtask_id";//后台任务ID
+
+        /**
+         * The version code
+         * <P> Type : INTEGER (long) </P>
+         */
+        public static final String VERSION = "version";//版本
+    }
+
+    public interface DataColumns {// 定义DataColumns的常量,用于后面创建数据库的表头
+        /**
+         * The unique ID for a row
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String ID = "_id";//定义DataColumns的部分常量
+
+        /**
+         * The MIME type of the item represented by this row.
+         * <P> Type: Text </P>
+         */
+        public static final String MIME_TYPE = "mime_type";//定义文件类型
+
+        /**
+         * The reference id to note that this data belongs to
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String NOTE_ID = "note_id";//便签ID
+
+        /**
+         * Created data for note or folder
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String CREATED_DATE = "created_date";//创建时间
+
+        /**
+         * Latest modified date//调整时间
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String MODIFIED_DATE = "modified_date";//最新的修改时间
+
+        /**
+         * Data's content
+         * <P> Type: TEXT </P>
+         */
+        public static final String CONTENT = "content";//定义数据包含的内容
+
+
+        /**
+         * Generic data column, the meaning is {@link #MIMETYPE} specific, used for//根据MIME类型的不同，对应下面5个不同属性
+         * integer data type
+         * <P> Type: INTEGER </P>
+         */
+        public static final String DATA1 = "data1";//文本内容的数据结构
+
+        /**
+         * Generic data column, the meaning is {@link #MIMETYPE} specific, used for
+         * integer data type
+         * <P> Type: INTEGER </P>
+         */
+        public static final String DATA2 = "data2";//文本模式
+
+        /**
+         * Generic data column, the meaning is {@link #MIMETYPE} specific, used for
+         * TEXT data type
+         * <P> Type: TEXT </P>
+         */
+        public static final String DATA3 = "data3";
+
+        /**
+         * Generic data column, the meaning is {@link #MIMETYPE} specific, used for
+         * TEXT data type
+         * <P> Type: TEXT </P>
+         */
+        public static final String DATA4 = "data4";
+
+        /**
+         * Generic data column, the meaning is {@link #MIMETYPE} specific, used for
+         * TEXT data type
+         * <P> Type: TEXT </P>
+         */
+        public static final String DATA5 = "data5";
+    }
+
+    public static final class TextNote implements DataColumns {// 对DataColumns的实现，建立一个新的类，textNote用于保存相关的信息。
+        /**
+         * Mode to indicate the text in check list mode or not// 清单模式的MODE=0，正常模式的MODE=1
+         * <P> Type: Integer 1:check list mode 0: normal mode </P>
+         */
+        public static final String MODE = DATA1;//电话号码
+
+        public static final int MODE_CHECK_LIST = 1;//设置为检查列表模式
+
+        public static final String CONTENT_TYPE = "vnd.android.cursor.dir/text_note";//内容的类型
+
+        public static final String CONTENT_ITEM_TYPE = "vnd.android.cursor.item/text_note";//内容项目类型
+
+        public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY + "/text_note");//关于电话的数据结构
+    }
+
+    public static final class CallNote implements DataColumns {//记录通话数据的表头
+        /**
+         * Call date for this record//通话记录
+         * <P> Type: INTEGER (long) </P>
+         */
+        public static final String CALL_DATE = DATA1;//存放通话时间信息
+
+        /**
+         * Phone number for this record
+         * <P> Type: TEXT </P>
+         */
+        public static final String PHONE_NUMBER = DATA3;//存放通话号码信息
+
+        public static final String CONTENT_TYPE = "vnd.android.cursor.dir/call_note";
+
+        public static final String CONTENT_ITEM_TYPE = "vnd.android.cursor.item/call_note";
+
+        public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY + "/call_note");//内容标识符
+    }
+}
diff --git a/doc/王培鑫小米便签精读部分/NotesDatabaseHelper.java b/doc/王培鑫小米便签精读部分/NotesDatabaseHelper.java
new file mode 100644
index 0000000..30577bf
--- /dev/null
+++ b/doc/王培鑫小米便签精读部分/NotesDatabaseHelper.java
@@ -0,0 +1,363 @@
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)//该模块主要是用于存储Notes的数据，以及根据数据更改Notes结构体的变量
+ *
+ * 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//许可证&操作权限
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.micode.notes.data;//包的名称
+
+import android.content.ContentValues;//数据库操作中保存数据信息
+import android.content.Context;//访问资源和加载
+import android.database.sqlite.SQLiteDatabase;//提供了对应于添加、删除、更新、查询的操作
+import android.database.sqlite.SQLiteOpenHelper;//数据库的更新和创建
+import android.util.Log;//安卓日志接口
+
+import net.micode.notes.data.Notes.DataColumns;//创建根目录文件夹、移动便签及清空垃圾文件夹
+import net.micode.notes.data.Notes.DataConstants;//移动便签 
+import net.micode.notes.data.Notes.NoteColumns;
+
+
+public class NotesDatabaseHelper extends SQLiteOpenHelper {// NotesDatabaseHelper类，继承于SQLiteOpenHelper类的子类。
+    private static final String DB_NAME = "note.db";//定义数据库的名称为“note.db”
+
+    private static final int DB_VERSION = 4;//数据库版本号
+
+    public interface TABLE {//将接口分成note和data
+        public static final String NOTE = "note";// 创建note表信息
+
+        public static final String DATA = "data";//创建data表信息
+    }
+
+    private static final String TAG = "NotesDatabaseHelper";//创建一个表格用来储存标签编号
+
+    private static NotesDatabaseHelper mInstance;//创建NotesDatabaseHelper的一个对象
+
+    private static final String CREATE_NOTE_TABLE_SQL =//增加文件夹
+        "CREATE TABLE " + TABLE.NOTE + "(" +//定义.减少文件夹
+            NoteColumns.ID + " INTEGER PRIMARY KEY," +//文件夹插入Note后需要更改的数据的表格
+            NoteColumns.PARENT_ID + " INTEGER NOT NULL DEFAULT 0," +//id自增
+            NoteColumns.ALERTED_DATE + " INTEGER NOT NULL DEFAULT 0," +
+            NoteColumns.BG_COLOR_ID + " INTEGER NOT NULL DEFAULT 0," +//应用界面颜色选择
+            NoteColumns.CREATED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +//创建时间数据
+            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," +//便签数量初始化为零 
+            NoteColumns.SNIPPET + " TEXT NOT NULL DEFAULT ''," +//Note中数据删除更改的数据表格
+            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" +// 数据库中需要存储的项目的名称，就相当于创建一个表格的表头的内容
+        ")";
+
+    private static final String CREATE_DATA_TABLE_SQL =//这是用于创建note中数据的表项的SQL语句
+        "CREATE TABLE " + TABLE.DATA + "(" +//note删除数据触发
+            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 ''" +
+        ")";//文件夹删除note触发
+
+    private static final String CREATE_DATA_NOTE_ID_INDEX_SQL =//创建数据的ID的索引
+        "CREATE INDEX IF NOT EXISTS note_id_index ON " +
+        TABLE.DATA + "(" + DataColumns.NOTE_ID + ");";//存储便签编号的一个数据表格
+
+    /**
+     * Increase folder's note count when move note to the folder//Increase增加文件
+Decrease减少文件
+     */
+    private static final String NOTE_INCREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =//当note移动到文件夹中时，文件夹的数量增加的功能
+        "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";//在文件夹中移入一个Note之后需要更改的数据的表格
+
+    /**
+     * Decrease folder's note count when move note from folder
+     */
+    private static final String NOTE_DECREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =//从文件夹中移出一个note时，更新数量
+        "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";//在文件夹中插入一个Note之后需要更改的数据的表格
+
+    /**
+     * Increase folder's note count when insert new note to the folder//在文件夹中新增文件
+     */
+    private static final String NOTE_INCREASE_FOLDER_COUNT_ON_INSERT_TRIGGER =//在文件夹中新建note时，更新数量
+        "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";//在文件夹中插入一个Note之后需要更改的数据的表格
+
+    /**
+     * Decrease folder's note count when delete note from the folder//在文件夹中删除文件
+     */
+    private static final String NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER =//在文件夹中删除note时，更新文件夹的note数量
+        "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";在文件夹中删除一个Note之后需要更改的数据的表格
+
+    /**
+     * Update note's content when insert data with type {@link DataConstants#NOTE}//在数据库中新增note或插入内容
+     */
+    private static final String DATA_UPDATE_NOTE_CONTENT_ON_INSERT_TRIGGER =//当note插入新的数据时，更新note的内容，并更改表格
+        "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";// 在文件夹中对一个Note导入新的数据之后需要更改的数据的表格
+
+    /**
+     * Update note's content when data with {@link DataConstants#NOTE} type has changed//note发生变化时触发update
+     */
+    private static final String DATA_UPDATE_NOTE_CONTENT_ON_UPDATE_TRIGGER =//当note的数据发生变化时，更新表格
+        "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";//Note数据被修改后需要更改的数据的表格
+
+    /**
+     * Update note's content when data with {@link DataConstants#NOTE} type has deleted//当类型被删除时，更新数据库
+     */
+    private static final String DATA_UPDATE_NOTE_CONTENT_ON_DELETE_TRIGGER =//当note的内容被删除时，更新表格的内容
+        "CREATE TRIGGER update_note_content_on_delete " +
+        " AFTER delete ON " + TABLE.DATA +
+        " WHEN old." + DataColumns.MIME_TYPE + "='" + DataConstants.NOTE + "'" +
+        " BEGIN" +//当data删除之后对数据进行更新
+        "  UPDATE " + TABLE.NOTE +
+        "   SET " + NoteColumns.SNIPPET + "=''" +
+        "  WHERE " + NoteColumns.ID + "=old." + DataColumns.NOTE_ID + ";" +
+        " END";// Note数据被删除后需要更改的数据的表格
+
+    /**
+     * Delete datas belong to note which has been deleted// 删除数据库中的数据，当这些数据在本地被删除
+     */
+    private static final String NOTE_DELETE_DATA_ON_DELETE_TRIGGER =//删除被删除的note的data
+        "CREATE TRIGGER delete_data_on_delete " +
+        " AFTER DELETE ON " + TABLE.NOTE +
+        " BEGIN" +
+        "  DELETE FROM " + TABLE.DATA +
+        "   WHERE " + DataColumns.NOTE_ID + "=old." + NoteColumns.ID + ";" +
+        " END";
+
+    /**
+     * Delete notes belong to folder which has been deleted
+     */
+    private static final String FOLDER_DELETE_NOTES_ON_DELETE_TRIGGER =//文件夹中删除文件，然后更改表格
+        "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";// 删除已删除的文件夹的便签后需要更改的数据的表格
+
+    /**
+     * Move notes belong to folder which has been moved to trash folder//移动笔记，当笔记从文件夹移动到垃圾文件夹时
+     */
+    private static final String FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER =//将垃圾文件夹里的note还原，并更新数据表格
+        "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";// 还原垃圾桶中便签后需要更改的数据的表格
+
+    public NotesDatabaseHelper(Context context) {//传入数据库的名称和版本
+        super(context, DB_NAME, null, DB_VERSION);
+    }
+
+    public void createNoteTable(SQLiteDatabase db) {//创建数据库，储存属性
+        db.execSQL(CREATE_NOTE_TABLE_SQL);
+        reCreateNoteTableTriggers(db);
+        createSystemFolder(db);
+        Log.d(TAG, "note table has been created");//调用系统输出调试信息，Log.d()是debug的意思。
+    }
+
+    private void reCreateNoteTableTriggers(SQLiteDatabase db) {//创建一个储存标签属性的表格
+        db.execSQL("DROP TRIGGER IF EXISTS increase_folder_count_on_update");//创建增加文件夹的触发器
+        db.execSQL("DROP TRIGGER IF EXISTS decrease_folder_count_on_update");//创建减少文件夹的触发器
+        db.execSQL("DROP TRIGGER IF EXISTS decrease_folder_count_on_delete");//创建删除减少文件夹的触发器
+        db.execSQL("DROP TRIGGER IF EXISTS delete_data_on_delete");//创建删除数据的触发器
+        db.execSQL("DROP TRIGGER IF EXISTS increase_folder_count_on_insert");//创建插入文件夹的触发器
+        db.execSQL("DROP TRIGGER IF EXISTS folder_delete_notes_on_delete");//创建删除note的触发器
+        db.execSQL("DROP TRIGGER IF EXISTS folder_move_notes_on_trash");//创建移除note的触发器
+
+        db.execSQL(NOTE_INCREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER);//创建自己的数据库操作
+        db.execSQL(NOTE_DECREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER);// 创建更新减少文件夹的触发器
+        db.execSQL(NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER);//创建删除减少文件夹的触发器
+        db.execSQL(NOTE_DELETE_DATA_ON_DELETE_TRIGGER);//创建删除标记已删除数据的触发器
+        db.execSQL(NOTE_INCREASE_FOLDER_COUNT_ON_INSERT_TRIGGER);// 创建插入文件夹的触发器
+        db.execSQL(FOLDER_DELETE_NOTES_ON_DELETE_TRIGGER);//创建删除notes的触发器
+        db.execSQL(FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER);//创建将回收站中的notes还原的触发器
+    }
+
+    private void createSystemFolder(SQLiteDatabase db) {//创建系统文件夹
+        ContentValues values = new ContentValues();//新建 ContantValues对象，储存基本数据类型
+
+        /**
+         * call record foler for call notes//创建callnote对应的文件夹
+         */
+        values.put(NoteColumns.ID, Notes.ID_CALL_RECORD_FOLDER);//将通话记录放入数据库
+        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
+        db.insert(TABLE.NOTE, null, values);
+
+        /**
+         * root folder which is default folder
+         */
+        values.clear();//创建默认文件夹
+        values.put(NoteColumns.ID, Notes.ID_ROOT_FOLDER);// 将数据库ID与通话记录文件夹ID形成映射
+        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);//将数据库中数据类型与通话记录文件夹类型形成映射
+        db.insert(TABLE.NOTE, null, values);//插入ContantValues对象
+
+        /**
+         * temporary folder which is used for moving note//设置临时文件夹作为文件移动的有效目标
+         */
+        values.clear();
+        values.put(NoteColumns.ID, Notes.ID_TEMPARAY_FOLDER);
+        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
+        db.insert(TABLE.NOTE, null, values);
+
+        /**
+         * create trash folder
+         */
+        values.clear();
+        values.put(NoteColumns.ID, Notes.ID_TRASH_FOLER);
+        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
+        db.insert(TABLE.NOTE, null, values);
+    }
+
+    public void createDataTable(SQLiteDatabase db) {//创建数据表格，储存便签内容
+        db.execSQL(CREATE_DATA_TABLE_SQL);
+        reCreateDataTableTriggers(db);//重新创建数据表的触发器
+        db.execSQL(CREATE_DATA_NOTE_ID_INDEX_SQL);
+        Log.d(TAG, "data table has been created");
+    }
+
+    private void reCreateDataTableTriggers(SQLiteDatabase db) {//重新创建数据表格触发器
+        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);
+    }
+
+    static synchronized NotesDatabaseHelper getInstance(Context context) {//如果NotesDatabaseHelper创建失败，就再创建一个，采取static synchronized类型，防止多线程发生错误
+        if (mInstance == null) {
+            mInstance = new NotesDatabaseHelper(context);
+        }
+        return mInstance;
+    }
+
+    @Override
+    public void onCreate(SQLiteDatabase db) {//自动创建数据库
+        createNoteTable(db);
+        createDataTable(db);
+    }
+
+    @Override
+    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {//数据库版本的更新，包括数据库内容的更改
+        boolean reCreateTriggers = false;//是否重建的信号
+        boolean skipV2 = false;//是否从V2升级到V3
+
+        if (oldVersion == 1) {//判断当前版本是不是一代
+            upgradeToV2(db);
+            skipV2 = true; // this upgrade including the upgrade from v2 to v3
+            oldVersion++;
+        }
+
+        if (oldVersion == 2 && !skipV2) {//判断旧版本是不是2号版本且没有跳过2号版本，就更新到3号版本
+            upgradeToV3(db);
+            reCreateTriggers = true;
+            oldVersion++;
+        }
+
+        if (oldVersion == 3) {//如果旧版本号为3号，就更新到4号版本
+            upgradeToV4(db);
+            oldVersion++;
+        }
+
+        if (reCreateTriggers) {//重新创建的同时，创建新的note table和datatable
+            reCreateNoteTableTriggers(db);
+            reCreateDataTableTriggers(db);
+        }
+
+        if (oldVersion != newVersion) {//判断当前版本是不是最新的
+            throw new IllegalStateException("Upgrade notes database to version " + newVersion
+                    + "fails");
+        }
+    }
+
+    private void upgradeToV2(SQLiteDatabase db) {//将数据库的版本更新到V2
+        db.execSQL("DROP TABLE IF EXISTS " + TABLE.NOTE);
+        db.execSQL("DROP TABLE IF EXISTS " + TABLE.DATA);
+        createNoteTable(db);
+        createDataTable(db);
+    }
+
+    private void upgradeToV3(SQLiteDatabase db) {//数据库版本升级到V3
+        // drop unused triggers
+        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");
+        // add a column for gtask id
+        db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.GTASK_ID
+                + " TEXT NOT NULL DEFAULT ''");
+        // add a trash system folder
+        ContentValues values = new ContentValues();// 添加一个垃圾文件夹
+        values.put(NoteColumns.ID, Notes.ID_TRASH_FOLER);//为变量赋值
+        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
+        db.insert(TABLE.NOTE, null, values);
+    }
+
+    private void upgradeToV4(SQLiteDatabase db) {//数据库版本升级到V4
+        db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.VERSION
+                + " INTEGER NOT NULL DEFAULT 0");
+    }
+}
diff --git a/doc/王培鑫小米便签精读部分/NotesProvider.java b/doc/王培鑫小米便签精读部分/NotesProvider.java
new file mode 100644
index 0000000..57e211a
--- /dev/null
+++ b/doc/王培鑫小米便签精读部分/NotesProvider.java
@@ -0,0 +1,305 @@
+/*
+ * 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;//以下 引用android自带的类，包括数据库等
+import android.content.ContentProvider;//导入ContentProvider
+import android.content.ContentUris;//导入ContentUris
+import android.content.ContentValues;//导入contentvalues
+import android.content.Intent;//导入intent
+import android.content.UriMatcher;//导入UriMatcher
+import android.database.Cursor;//查询数据库所需的游标
+import android.database.sqlite.SQLiteDatabase;//引入SQLite数据库
+import android.net.Uri;
+import android.text.TextUtils;//文本识别处理工具
+import android.util.Log;
+
+import net.micode.notes.R;//访问、删除、插入、更新、扩展Notes的数据库
+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 {//为存储和获取数据提供接口。可以在不同的应用程序之间共享数据
+    private static final UriMatcher mMatcher;//UriMatcher用于匹配Uri
+
+    private NotesDatabaseHelper mHelper;//数据库辅助类的实例化
+
+    private static final String TAG = "NotesProvider";//该类的自定义标签
+
+    private static final int URI_NOTE            = 1;//定义几种Uri的代号
+    private static final int URI_NOTE_ITEM       = 2;//注册Uri路径的过程
+    private static final int URI_DATA            = 3;
+    private static final int URI_DATA_ITEM       = 4;
+
+    private static final int URI_SEARCH          = 5;
+    private static final int URI_SEARCH_SUGGEST  = 6;
+
+    static {//代码段：这是一个注册URI路径的过程
+        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);//SUGGEST_URI_PATH_QUERY 并不属于URI的一部分，而应是用于指向此路径的常量。
+        mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY + "/*", URI_SEARCH_SUGGEST);
+    }//注册完需要匹配的Uri后，就可以使用sMatcher.match(uri)方法对输入的Uri进行匹配
+
+    /**
+     * x'0A' represents the '\n' character in sqlite. For title and content in the search result,//trim()函数是去掉字符串头尾空格的函数
+     * we will trim '\n' and white space in order to show more information.
+     */
+    private static final String NOTES_SEARCH_PROJECTION = NoteColumns.ID + ","
+        + NoteColumns.ID + " AS " + SearchManager.SUGGEST_COLUMN_INTENT_EXTRA_DATA + ","// 设置表明额外数据、推荐显示的文本、图标、操作、数据
+        + "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;
+
+    private static String NOTES_SNIPPET_SEARCH_QUERY = "SELECT " + NOTES_SEARCH_PROJECTION// 便签的搜索、查询
+        + " FROM " + TABLE.NOTE// 在特定表中某一字段检索特定子串
+        + " WHERE " + NoteColumns.SNIPPET + " LIKE ?"
+        + " AND " + NoteColumns.PARENT_ID + "<>" + Notes.ID_TRASH_FOLER
+        + " AND " + NoteColumns.TYPE + "=" + Notes.TYPE_NOTE;
+
+    @Override
+    public boolean onCreate() {//创建标签记录的表
+        mHelper = NotesDatabaseHelper.getInstance(getContext());
+        return true;
+    }
+
+    @Override
+    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,//查询uri在数据库中对应的位置
+            String sortOrder) {
+        Cursor c = null;//创建空游 标
+        SQLiteDatabase db = mHelper.getReadableDatabase();//获取可读数据库
+        String id = null;
+        switch (mMatcher.match(uri)) {//匹配查找uri
+            case URI_NOTE:
+                c = db.query(TABLE.NOTE, projection, selection, selectionArgs, null, null,
+                        sortOrder);
+                break;
+            case URI_NOTE_ITEM://查询便签条目
+                id = uri.getPathSegments().get(1);
+                c = db.query(TABLE.NOTE, projection, NoteColumns.ID + "=" + id
+                        + parseSelection(selection), selectionArgs, null, null, sortOrder);
+                break;
+            case URI_DATA://根据日期进行查询
+                c = db.query(TABLE.DATA, projection, selection, selectionArgs, null, null,
+                        sortOrder);
+                break;
+            case URI_DATA_ITEM:
+                id = uri.getPathSegments().get(1);//根据日期条目进行查询
+                c = db.query(TABLE.DATA, projection, DataColumns.ID + "=" + id
+                        + parseSelection(selection), selectionArgs, null, null, sortOrder);
+                break;
+            case URI_SEARCH:
+            case URI_SEARCH_SUGGEST:
+                if (sortOrder != null || projection != null) {//不合法的参数
+                    throw new IllegalArgumentException(
+                            "do not specify sortOrder, selection, selectionArgs, or projection" + "with this query");
+                }
+
+                String searchString = null;
+                if (mMatcher.match(uri) == URI_SEARCH_SUGGEST) {//与搜索相关的ur
+                    if (uri.getPathSegments().size() > 1) {
+                        searchString = uri.getPathSegments().get(1);
+                    }
+                } else {
+                    searchString = uri.getQueryParameter("pattern");//截取Uri链接中的参数"pattern"
+                }
+
+                if (TextUtils.isEmpty(searchString)) {
+                    return null;
+                }
+
+                try {//抛出异常
+                    searchString = String.format("%%%s%%", searchString);
+                    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);
+        }
+        if (c != null) {
+            c.setNotificationUri(getContext().getContentResolver(), uri);//若getContentResolver发生变化，就接收通知
+        }
+        return c;
+    }
+
+    @Override
+    public Uri insert(Uri uri, ContentValues values) {//插入一个uri，uri是一个用于标识某一互联网资源名称的字符串
+        SQLiteDatabase db = mHelper.getWritableDatabase();//获得可写的数据库
+        long dataId = 0, noteId = 0, insertedId = 0;
+        switch (mMatcher.match(uri)) {//数据库的插入，用来存放数据
+            case URI_NOTE:
+                insertedId = noteId = db.insert(TABLE.NOTE, null, values);
+                break;
+            case URI_DATA:
+                if (values.containsKey(DataColumns.NOTE_ID)) {//匹配note的ID
+                    noteId = values.getAsLong(DataColumns.NOTE_ID);
+                } else {
+                    Log.d(TAG, "Wrong data format without note id:" + values.toString());
+                }//Log用于显示，格式错误
+                insertedId = dataId = db.insert(TABLE.DATA, null, values);//插入便签数据
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri);
+        }
+        // Notify the note uri
+        if (noteId > 0) {//更新内容
+            getContext().getContentResolver().notifyChange(
+                    ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null);
+        }
+
+        // Notify the data uri
+        if (dataId > 0) {//更新日期
+            getContext().getContentResolver().notifyChange(
+                    ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId), null);
+        }
+
+        return ContentUris.withAppendedId(uri, insertedId);//最后返回插入uri的路径
+    }
+
+    @Override
+    public int delete(Uri uri, String selection, String[] selectionArgs) {//删除一个uri
+        int count = 0;
+        String id = null;
+        SQLiteDatabase db = mHelper.getWritableDatabase();//获得可写的数据库
+        boolean deleteData = false;
+        switch (mMatcher.match(uri)) {//查找匹配的uri
+            case URI_NOTE:
+                selection = "(" + selection + ") AND " + NoteColumns.ID + ">0 ";
+                count = db.delete(TABLE.NOTE, selection, selectionArgs);
+                break;
+            case URI_NOTE_ITEM:
+                id = uri.getPathSegments().get(1);
+                /**
+                 * ID that smaller than 0 is system folder which is not allowed to
+                 * trash
+                 */
+                long noteId = Long.valueOf(id);
+                if (noteId <= 0) {//ID小于0表示是系统文件夹，不能删除
+                    break;
+                }
+                count = db.delete(TABLE.NOTE,
+                        NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
+                break;
+            case URI_DATA:
+                count = db.delete(TABLE.DATA, selection, selectionArgs);//删除内容
+                deleteData = true;
+                break;
+            case URI_DATA_ITEM:
+                id = uri.getPathSegments().get(1);//通过数据条目查找到
+                count = db.delete(TABLE.DATA,
+                        DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
+                deleteData = true;
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri);//未知uri，则报错，显示Unknown URI
+        }
+        if (count > 0) {//对上述的操作进行判断，上述更改发生，count>0
+            if (deleteData) {//如果真的删除了数据，则要求监听器对观察者发送通知
+                getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);//所有修改要对观察者进行提醒
+            }
+            getContext().getContentResolver().notifyChange(uri, null);//对所有修改进行通知
+        }
+        return count;
+    }
+
+    @Override
+    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {//数据库更新uri
+        int count = 0;
+        String id = null;
+        SQLiteDatabase db = mHelper.getWritableDatabase();//获取可写数据库
+        boolean updateData = false;
+        switch (mMatcher.match(uri)) {//根据不同的uri，更新数据库
+            case URI_NOTE:
+                increaseNoteVersion(-1, selection, selectionArgs);//升级note版本
+                count = db.update(TABLE.NOTE, values, selection, selectionArgs);//数据更新
+                break;
+            case URI_NOTE_ITEM:
+                id = uri.getPathSegments().get(1);
+                increaseNoteVersion(Long.valueOf(id), selection, selectionArgs);
+                count = db.update(TABLE.NOTE, values, NoteColumns.ID + "=" + id
+                        + parseSelection(selection), selectionArgs);
+                break;
+            case URI_DATA:
+                count = db.update(TABLE.DATA, values, selection, selectionArgs);//对该data的uri进行更新
+                updateData = true;
+                break;
+            case URI_DATA_ITEM:
+                id = uri.getPathSegments().get(1);//获取该项目id并将其uri更新
+                count = db.update(TABLE.DATA, values, DataColumns.ID + "=" + id
+                        + parseSelection(selection), selectionArgs);
+                updateData = true;
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri);// 抛出错误：未知uri
+        }
+
+        if (count > 0) {//如果发生了更改，进行通知
+            if (updateData) {//data更新
+                getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
+            }
+            getContext().getContentResolver().notifyChange(uri, null);
+        }
+        return count;
+    }
+
+    private String parseSelection(String selection) {//返回字符串规定格式
+        return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : "");
+    }
+
+    private void increaseNoteVersion(long id, String selection, String[] selectionArgs) {//升级note的版本
+        StringBuilder sql = new StringBuilder(120);//创建stringbuilder对象
+        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)) {// 如果id>0且selection不为空，添加“WHERE”
+            sql.append(" WHERE ");
+        }
+        if (id > 0) {
+            sql.append(NoteColumns.ID + "=" + String.valueOf(id));
+        }
+        if (!TextUtils.isEmpty(selection)) {//若selection字段为空，则添加该字段
+            String selectString = id > 0 ? parseSelection(selection) : selection;
+            for (String args : selectionArgs) {
+                selectString = selectString.replaceFirst("\\?", args);
+            }
+            sql.append(selectString);//增加selectString语句
+        }
+
+        mHelper.getWritableDatabase().execSQL(sql.toString());//把修改后的sql加入数据库
+    }
+
+    @Override
+    public String getType(Uri uri) {//获取uri的类型
+        // TODO Auto-generated method stub
+        return null;//初始化，返回一个空指针
+    }
+
+}