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(){@Overridepublic 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

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