AsyncQueryHandler与ContentProvider关联进行ListView的异步操作

转自：http://blog.csdn.net/imdxt1986/article/details/7107945

AsyncQueryHandler

 

AsyncQueryHandler是Handler的子类，文档上说，如果处理ContentProvider相关的内容，不用需要自行定义一套东西， 而可以简单的使用async方式。我想指代的就应该是AsyncQueryHandler类。该类是一个典型的模板类，为ContentProvider 的增删改查提供了很好的接口，提供了一个解决架构，final了一些方法，置空了一些方法。通过派生，实例化一些方法（不是每个对 ContentProvider的处理多需要全部做增删改查，我想这也是该类默认置空一些方法而不是抽象一些方法的原因），来达到这个目的。在内部，该类 隐藏了多线程处理的细节，当你使用时，你会感觉异常便利。以query为例，你可以这么来用：

    // 定义一个handler，采用的是匿名类的方式，只处理query，因此只重写了onQueryComplete函数：
    queryHandler = new AsyncQueryHandler(this.getContentResolver()){ // 传入的是一个ContentResolver实例，所以必须在OnCreate后实例化该Handler类
    @Override
    protected void onQueryComplete(int token, Object cookie, Cursor cursor) {
            // 在这里你可以获得一个cursor和你传入的附加的token和cookie。
            // 该方法在当前线程下（如果传入的是默认的Looper话），可以自由设定UI信息
        }
    };

    // 调用时只需要调用startQuery(int token, Object cookie, ContentURI uri, String[] projection, String selection, String[] selectionArgs, String sortOrder)函数即可：

    queryHandler.startQuery(token, cookie, uri, projection, selection, selectionArgs, sortBy);

    1. 当你实例化一个AsyncQueryHandler类时（包括其子类...），它会单件构造一个线程（后面会详述...），这个线程里面会构建一个消息循环。
    2. 获得该消息循环的指针，用它做参数实例化另一个Handler类，该类为内部类。至此，就有了两个线程，各自有一个Handler来处理消息。
    3. 当调用onXXX的时候，在XXX函数内部会将请求封装成一个内部的参数类，将其作为消息的参数，将此消息发送至另一个线程。
    4. 在该线程的Handler中，接受该消息，并分析传入的参数，用初始化时传入的ContentResolver进行XXX操作，并返回Cursor或其他返回值。
    5. 构造一个消息，将上述返回值以及其他相关内容绑定在该消息上，发送回主线程。
    6. 主线程默认的AsyncQueryHandler类的handleMessage方法（可自定义，但由于都是内部类，基本没有意义...）会分析该消息，并转发给对应的onXXXComplete方法。
    7. 用户重写的onXXXComplete方法开始工作。

好了 直接上代码：

 

package org.dxt.list;import static android.view.Window.PROGRESS_VISIBILITY_OFF;import static android.view.Window.PROGRESS_VISIBILITY_ON;import android.app.ListActivity;import android.content.AsyncQueryHandler;import android.content.ContentResolver;import android.content.ContentValues;import android.database.Cursor;import android.net.Uri;import android.os.Bundle;import android.util.Log;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.Window;import android.widget.CursorAdapter;import android.widget.EditText;import android.widget.ListView;import android.widget.SimpleCursorAdapter;import android.widget.TextView;import android.widget.Toast;public class AsyncQueryActivity extends ListActivity {private ListView myListView;private EditText myEditText_Name;private EditText myEditText_Tel;private String name = null;private String tel = null;private MyQueryHandler mAsyncQueryActivity;private CursorAdapter mCursorAdapter;private Cursor mCursor = null;private TextView mEmptyText;protected final static int MENU_ADD = Menu.FIRST;protected final static int MENU_UPDATE = Menu.FIRST + 1;protected final static int MENU_DELETE = Menu.FIRST + 2;protected final static int MENU_SEARCH = Menu.FIRST + 3;protected final static int MENU_SEARCH_ALL = Menu.FIRST + 4;protected final static int MENU_DELETE_ALL = Menu.FIRST + 5;protected static final String ADD = "add";protected static final String UPDATE = "update";protected static final String DELETE = "delete";protected static final String SEARCH = "search";protected static final String SEARCH_ALL = "search_all";protected static final String DELETE_ALL = "delete_all";private static final String[] COLUMN_NAMES = new String[] { MyUsers.User.USER_NAME, MyUsers.User.USER_TEL };protected static final int QUERY_TOKEN = 0;protected static final int INSERT_TOKEN = 1;protected static final int UPDATE_TOKEN = 2;protected static final int DELETE_TOKEN = 3;protected static final int DELETE_TOKEN_ALL = 4;protected static final int SEARCH_TOKEN = 5;protected int mInitialSelection = -1;@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// TODO Auto-generated method stubsuper.onCreateOptionsMenu(menu);menu.add(Menu.NONE, MENU_ADD, 0, R.string.ADD);menu.add(Menu.NONE, MENU_UPDATE, 0, R.string.EDIT);menu.add(Menu.NONE, MENU_DELETE, 0, R.string.DELETE);menu.add(Menu.NONE, MENU_SEARCH, 0, R.string.SEARCH);menu.add(Menu.NONE, MENU_SEARCH_ALL, 0, R.string.SEARCH_ALL);menu.add(Menu.NONE, MENU_DELETE_ALL, 0, R.string.DELETE_ALL);return true;}@Overridepublic boolean onOptionsItemSelected(MenuItem item) {// TODO Auto-generated method stubsuper.onOptionsItemSelected(item);switch (item.getItemId()) {case MENU_ADD:operation(ADD);break;case MENU_UPDATE:operation(UPDATE);break;case MENU_DELETE:operation(DELETE);break;case MENU_SEARCH:operation(SEARCH);break;case MENU_SEARCH_ALL:operation(SEARCH_ALL);break;case MENU_DELETE_ALL:operation(DELETE_ALL);break;default:break;}return true;}private void initWidget() {//int ScreenWidth = getWindowManager().getDefaultDisplay().getWidth();//int ScreenHight = getWindowManager().getDefaultDisplay().getHeight();//Log.d("tag", "ScreenWidth = " + ScreenWidth + "ScreenHight =  "//+ ScreenHight);myEditText_Name = (EditText) findViewById(R.id.EditText_Name);myEditText_Tel = (EditText) findViewById(R.id.EditText_Tel);myListView = (ListView) findViewById(android.R.id.list);}private void getUserInput() {name = myEditText_Name.getText().toString().trim();//  除去两头的空格tel = myEditText_Tel.getText().toString().trim();}/** Called when the activity is first created. */@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.asnyclist);initWidget();mEmptyText = (TextView) findViewById(android.R.id.empty);mAsyncQueryActivity = new MyQueryHandler(getContentResolver());}@Overrideprotected void onListItemClick(ListView l, View v, int position, long id) {// TODO Auto-generated method stubsuper.onListItemClick(l, v, position, id);Log.d("tag", "position------>" + position);// 在这个view上的位置}@Overrideprotected void onResume() {// TODO Auto-generated method stubsuper.onResume();query();}@Overrideprotected void onStop() {// TODO Auto-generated method stubsuper.onStop();if (mCursor != null) {mCursor.deactivate();}}private void query() {mAsyncQueryActivity.startQuery(QUERY_TOKEN, null,MyUsers.User.CONTENT_URI,null, null, null, "_id desc");displayProgress(true);}private void reQuery() {query();}private void displayProgress(boolean flag) {mEmptyText.setText(flag ? R.string.simContacts_emptyLoading: R.string.simContacts_empty);getWindow().setFeatureInt(Window.FEATURE_INDETERMINATE_PROGRESS,flag ? PROGRESS_VISIBILITY_ON : PROGRESS_VISIBILITY_OFF);}private void setAdapter() {if (mCursorAdapter == null) {mCursorAdapter = newAdapter();myListView.setAdapter(mCursorAdapter);//setListAdapter(mCursorAdapter);} else {mCursorAdapter.changeCursor(mCursor);myListView.invalidateViews();// 更新listview}if (mInitialSelection >= 0&& mInitialSelection < mCursorAdapter.getCount()) {setSelection(mInitialSelection);getListView().setFocusableInTouchMode(true);boolean gotfocus = getListView().requestFocus();}}protected CursorAdapter newAdapter() {return new SimpleCursorAdapter(this, R.layout.testlist, mCursor,COLUMN_NAMES, new int[] { R.id.name_text,R.id.tel_text });}private void operation(String cmd) {getUserInput();if (cmd.equals(ADD)) {insert();} else if (cmd.equals(UPDATE)) {update();} else if (cmd.equals(DELETE)) {delete();} else if (cmd.equals(SEARCH)) {search();} else if (cmd.equals(SEARCH_ALL)) {query();} else if (cmd.equals(DELETE_ALL)) {deleteAll();//reQuery();}myEditText_Name.setText("");myEditText_Tel.setText("");}private void insert() {if (name.equals("") || tel.equals("")) {Toast.makeText(this, "请输入您要插入数据的用户名！", Toast.LENGTH_SHORT).show();} else {ContentValues values = new ContentValues();values.put(MyUsers.User.USER_NAME, name);values.put(MyUsers.User.USER_TEL, tel);mAsyncQueryActivity.startInsert(INSERT_TOKEN, null,MyUsers.User.CONTENT_URI,values);}}private void delete() {if (name.equals("")) {Toast.makeText(this, "请输入您要删除数据的用户名！", Toast.LENGTH_SHORT).show();} else {mAsyncQueryActivity.startDelete(DELETE_TOKEN, null, MyUsers.User.CONTENT_URI, MyUsers.User.USER_NAME+"=?", new String[]{name});Toast.makeText(this, "删除" + name + " 成功！", Toast.LENGTH_SHORT).show();}}private void update() {if (name.equals("")) {Toast.makeText(this, "请输入您要更新数据的用户名！", Toast.LENGTH_SHORT).show();} else if (tel.equals("")) {Toast.makeText(this, "请输入您要更新数值", Toast.LENGTH_SHORT).show();} else {ContentValues values = new ContentValues();//values.put(MyUsers.User.USER_NAME, name);values.put(MyUsers.User.USER_TEL, tel);mAsyncQueryActivity.startUpdate(UPDATE_TOKEN, null, MyUsers.User.CONTENT_URI, values,MyUsers.User.USER_NAME + "=?", new String[]{name});Toast.makeText(this, "更新为" + tel + " 成功！", Toast.LENGTH_SHORT).show();}}private void search() {if (name.equals("")) {Toast.makeText(this, "请输入您要查找数据的用户名！", Toast.LENGTH_SHORT).show();} else {mAsyncQueryActivity.startQuery(SEARCH_TOKEN, null, MyUsers.User.CONTENT_URI, null,MyUsers.User.USER_NAME+"=?", new String[]{name}, null);}}private void deleteAll() {mAsyncQueryActivity.startDelete(DELETE_TOKEN_ALL, null, MyUsers.User.CONTENT_URI, null, null);Toast.makeText(this, "清空成功喽！", Toast.LENGTH_SHORT).show();}private class MyQueryHandler extends AsyncQueryHandler {public MyQueryHandler(ContentResolver cr) {super(cr);// TODO Auto-generated constructor stub}@Overrideprotected void onDeleteComplete(int token, Object cookie, int result) {// TODO Auto-generated method stubsuper.onDeleteComplete(token, cookie, result);Log.d("tag", "onDeleteComplete--->"+result);reQuery();}@Overrideprotected void onInsertComplete(int token, Object cookie, Uri uri) {// TODO Auto-generated method stubsuper.onInsertComplete(token, cookie, uri);Log.d("tag", "onInsertComplete--->");reQuery();}@Overrideprotected void onQueryComplete(int token, Object cookie, Cursor cursor) {// TODO Auto-generated method stubsuper.onQueryComplete(token, cookie, cursor);Log.d("tag", "onQueryComplete--->");mCursor = cursor;setAdapter();if(cursor.getCount()>0){displayProgress(false);}else{displayProgress(true);}}@Overrideprotected void onUpdateComplete(int token, Object cookie, int result) {// TODO Auto-generated method stubsuper.onUpdateComplete(token, cookie, result);Log.d("tag", "onUpdateComplete--->");reQuery();}}}