说明：（之前只用handle是因为主线程默认就加上Looper.prepare()和Looper.loop()的。所以主线程可以通过handle收发信息，但是如果在thread里面的话，就是工作线程，工作线程的话，默认是没有加上那两段代码的，所以要手动加上，然后再通过handle.sendMessage()发送信息到工作线程才能取到信息）

主显示布局以及代码：

activity_main.xml：

<LinearLayout 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:orientation="vertical">


    <Button 
        android:id="@+id/btDownload"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="点击下载"
        />
    <ProgressBar 
        android:id="@+id/pbDownload"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:max="100"
        android:progress="2"
        style="@android:style/Widget.ProgressBar.Horizontal"
        />
<TextView 
   android:id="@+id/tvDownload"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:text="0%"/>

</LinearLayout>

java代码：

package com.litsoft.main;


import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.os.SystemClock;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;


public class MainActivity extends ActionBarActivity {

private ProgressBar pbDownload;
private TextView tvDownload;
private Handler mmainHanlder,mworkHandler;

private static final int DOWNLOAD_START = 0;
private static final int DOWNLOADING = 1;
private static final int DOWNLOAD_FINISH = 2;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initview();
initMainHandler();
createWorkHandler();
setListener();
}
private void setListener() {
// TODO Auto-generated method stub
findViewById(R.id.btDownload).setOnClickListener(new OnClickListener() {

@Override
public void onClick(View view) {
// TODO Auto-generated method stub
mworkHandler.sendEmptyMessage(DOWNLOAD_START);
}
});
}
private void createWorkHandler() {
// TODO Auto-generated method stub
new Thread(){
public void run() {
Looper.prepare();//创建Looper对象和工作线程中的MessageQueue
mworkHandler = new Handler(){
public void handleMessage(Message msg) {
if(msg.what==DOWNLOAD_START){
for(int i=0;i<=100;i++){
SystemClock.sleep(2000);
pbDownload.setProgress(i);
Message msg1 = new Message();
msg1.what = DOWNLOADING;
msg1.arg1 = i;
mmainHanlder.sendMessage(msg1);
}
Message msg2 = new Message();
msg2.what = DOWNLOAD_FINISH;
mmainHanlder.sendMessage(msg2);
}
};
};
Looper.loop();//轮询工作线程中的消息队列
};

}.start();
}
private void initMainHandler() {
// TODO Auto-generated method stub
mmainHanlder = new Handler(){
@Override
public void handleMessage(Message msg) {
// TODO Auto-generated method stub
super.handleMessage(msg);
switch(msg.what){
 case DOWNLOADING:
 tvDownload.setText(msg.arg1+"%");
 break;
 case DOWNLOAD_FINISH:
 Toast.makeText(MainActivity.this, "已经完成下载", 20000);
 break;
}
}
};
}
private void initview() {
// TODO Auto-generated method stub
pbDownload = (ProgressBar) findViewById(R.id.pbDownload);
tvDownload = (TextView) findViewById(R.id.tvDownload);
}



}

效果：

本文出自 “追随心的彼岸” 博客，谢绝转载！

线程通信之looper之用法--主线程和工作线程