Android线程---UI线程和非UI线程之间通信

    近期自学到了线程这一块，用了一上午的时间终于搞出来了主、子线程间的相互通信。当主线程sendMessage后，子线程便会调用handleMessage来获取你所发送的Message。我的主线程向子线程发送消息时携带了数据，子线程根据主线程发送来的数据进行数据库查询，并将查询后的结果返回给该主线程：

 

 public class UpdataPeople extends Activity {
 
    EditText updata_name;
    EditText updata_phone;
    EditText updata_address;
    Button updata_quxiao;
    Button updata_baocun;
 
    String name;
    String phone;
 
    //创建一个子线程对象
    UpdataThread updataThread ;
 
    //定义一个全局变量，该Handler在主线程中重写HandleMessage。
    //若不定义成为全局变量，则在子线程中无发用到该Handler
    private Handler mainHandler = null;
 
    //创建一个非UI线程
    class UpdataThread extends Thread {
 
        public Handler mhandler;
 
        public void run() {
            Looper.prepare();
            mhandler = new Handler() {
 
                //定义处理消息的方法
                @Override
                public void handleMessage(Message msg) {
                    //---这里面做一些耗时操作
                    if (msg.what == 0x123) {
                        //获取msg所携带的数据
                        Bundle bundle = msg.getData();
                        if (bundle != null) {
                            String name = bundle.getString("name");
                            String phone = bundle.getString("phone");
                            Toast.makeText(getApplication(), "传值成功" + name + phone, Toast.LENGTH_LONG).show();
                        } else {
                            name = " ";
                            phone = " ";
                        }
                        //创建并连接数据库，若该数据库已经存在，则打开该数据库
                        CreateDatabaseHelper cdh = new CreateDatabaseHelper(getApplication(), "myPeople.db3", 1);
                        //使用游标查询数据库，并返回结果集
                        Cursor cursor = cdh.getReadableDatabase().rawQuery("select * from people where name = ? and phone = ?", new String[]{name, phone});
                        //创建一个Bundle存储查询出来的结果
                        Bundle dataAll = new Bundle();
                        //遍历cursor，并将结果赋值给Bundle
                        while (cursor.moveToNext()) {
                            dataAll.putString("name", cursor.getString(1));
                            dataAll.putString("phone", cursor.getString(2));
                            dataAll.putString("address", cursor.getString(3));
                        }
    //↓↓↓↓↓↓↓这一块便是子线程将查询的结果返回给主线程↓↓↓↓↓↓↓
                        //创建Message
                        Message msg_main = new Message();
                        msg_main.what = 0x456;
                        //为Message添加数据
                        msg_main.setData(dataAll);
                        //向主线程发送消息
                        mainHandler.sendMessage(msg_main);
 
                    }
                }
            };
            Looper.loop();
        }
    }
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //实例化Thread
        updataThread = new UpdataThread();
        //启动新线程
        updataThread.start();
        setContentView(R.layout.updatapeople);
        //获取布局文件里的控件
        updata_name = (EditText) findViewById(R.id.updata_name);
        updata_phone = (EditText) findViewById(R.id.updata_phone);
        updata_address = (EditText) findViewById(R.id.updata_address);
        updata_quxiao = (Button) findViewById(R.id.updata_quxiao);
        updata_baocun = (Button) findViewById(R.id.updata_baocun);
 
        //获取启动该Activity的Intent
        Intent intent = getIntent();
        //取出Intent所携带的数据包
        Bundle datas = intent.getExtras();
        //取出包中所携带的各种数据
        if (datas != null) {
            name = datas.getString("name");
            phone = datas.getString("phone");
        } else {
            name = "空";
            phone = "空";
        }
//↓↓↓↓↓↓↓这一块便是主线程向子线程发送消息↓↓↓↓↓↓↓↓
        //创建消息
        Message msg = new Message();
        //为msg标记一下(类似与--key--)
        msg.what = 0x123;
        //创建一个Bundle,并存放数据
        Bundle bundle = new Bundle();
        bundle.putString("name", name);
        bundle.putString("phone", phone);
        //将数据添加到msg
        msg.setData(bundle);
        //向新线程发送消息
        updataThread.mhandler.sendMessage(msg);
 
        //接受子线程返回的消息和子线程那边的用法一样
         mainHandler = new Handler() {
            @Override
            public void handleMessage(Message msg_main) {
                if (msg_main.what == 0x456){
                    //更新UI(因为在UI 线程中可以进行UI的更新。。。)
                    updata_name.setText(msg_main.getData().getString("name"));
                }
            }
        };