Handler消息传递机制(三)管理MessageQueue的Looper

package com.example.looper;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends Activity {

private Button send;
private TextView textView;
private MyHandler myHandler;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
send = (Button) findViewById(R.id.button1);
textView = (TextView) findViewById(R.id.textView1);
Looper looper = Looper.myLooper();
myHandler = new MyHandler(looper);
//也可用无参构造方法，系统会有一个默认的Looper来管理消息队列
send.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
// 启动线程
new Thread(new MyThread()).start();
}
});
}

public class MyHandler extends Handler{
public MyHandler() {

}
public MyHandler(Looper looper) {
super(looper);
}
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
textView.setText("--obj-->>" + msg.obj);
}
}
public class MyThread implements Runnable{

@Override
public void run() {
Message message = Message.obtain();
message.what = 1;
message.obj = "Rose";
myHandler.sendMessage(message);
}
}
}

<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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.looper.MainActivity" >

<Button
android:id="@+id/button1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="56dp"
android:text="发送消息" />

<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/button1"
android:layout_centerHorizontal="true"
android:layout_marginTop="119dp"
android:textSize="30dp"
android:text="TextView" />

</RelativeLayout>