Android开发基础之Main线程向Worker线程发送消息

一 布局

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">

    <Button android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="send"
        android:id="@+id/button"/>

</RelativeLayout>

如图：

二 代码

    private Button button;
    private Handler handler;

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

        button = (Button)this.findViewById(R.id.button);
        button.setOnClickListener(new ButtonListener());

        WorkerThread thread = new WorkerThread();
        thread.start();
    }

    class ButtonListener implements View.OnClickListener {
        @Override
        public void onClick(View v) {
            Message msg = handler.obtainMessage();
            handler.sendMessage(msg);
        }
    }

    class WorkerThread extends Thread {
        public void run() {
            Looper.prepare();
            handler = new Handler(){
                public void handleMessage(Message msg){
                    System.out.println("Message From MainThread");
                }
            };
            Looper.loop();
        }
    }

三 结果