Android MainThread（UI線程/主線程） 與 WorkThread（主線程以外的線程） 相互sendMessage

WorkThread sendMessage to MainThread

private void SimpleThread() {
        final Handler handler = new Handler(){

            @Override
            public void handleMessage(Message msg) {
                Log.i("zht","msg.what" +msg.what);
            }

        };

        Runnable mRunnable = new Runnable() {
            @Override
            public void run() {
                Message msg = new Message();
                msg.what =102;
                handler.sendMessage(msg);

            }
        };
        Thread thread = new Thread(mRunnable);

        thread.start();
    }

MainThread sendMessage to workThread
在ui線程之外的線程裏處理 message （handleMessage）
必須調用
Looper.prepare();
Looper.loop();

    Handler handler = null;
    private void SimpleThread() {

        Runnable mRunnable = new Runnable() {
            @Override
            public void run() {
                Looper.prepare();
                handler = new Handler() {
                    @Override
                    public void handleMessage(Message msg) {
                        Log.i("zht", "msg.what:" + msg.what);
                    }
                };
                Looper.loop();

            }
        };
        Thread thread = new Thread(mRunnable);

        thread.start();
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        Message msg = new Message();
        msg.what = 101;
        handler.sendMessage(msg);
    }