Android Handler：子线程发消息到UI主线程

Activity代码：

public class MainActivity extends Activity {
    private MyThread myThread;
    private Handler handler; //子线程与UI主线程进行消息通信

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        //通过Handler获取子线程推送过来的消息
		handler = new Handler(){
			@Override
			public void handleMessage(Message msg) {
				super.handleMessage(msg);
				Bundle bundle = msg.getData();
				String value = bundle.getString("value");
				outputEditText.setText(value);
			}
		};

		//启动一个子线程
		myThread = new MyThread(handler);
		myThread.start();

		showDialog("Socket Thread Started!");
    }

    /**
     * 对话框显示
     */
    private void showDialog(String msg){
        new AlertDialog.Builder(this)
                .setTitle("提示")
                .setMessage(msg)
                .setPositiveButton("ok", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {

            }
        }).show();
    }
}

 

Thread代码：

public class MyThread extends Thread{
    private Handler handler;

    public MyThread(Handler handler){
        this.handler = handler;
    }

    @Override
    public void run() {
        try {
            //持续向UI主线程发送当前日期时间
            while(true){
                TimeUnit.MILLISECONDS.sleep(1000);

                SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
                String date = sdf.format(new Date());

                sendMessage(date);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 向UI主线程发送消息
     */
    private void sendMessage(String msg){
        Bundle data = new Bundle();
        data.putString("value", msg);

        Message message = new Message();
        message.setData(data);

        this.handler.sendMessage(message);
    }
}

 

需要刷新UI时的Handle实例化：

        在主线程中： Handler handler = new Handler();

        在其他线程中： Handler handler = new Handler(Looper.getMainLooper());

不用刷新UI时的Handle实例化：

        在主线程中： Handler handler = new Handler();

        在其他线程中： 

                Looper.prepare(); 

                Handler handler = new Handler();

                Looper.loop();

                或者

                Handler handler = new Handler(Looper.getMainLooper());

        message.what一般用于区别消息的。进程内传递数据可用setData(Bundle)，进程间要用message.obj传递可序列化对象数据