android中的 Handler机制

使用Handler机制实现向主线程中发送消息，实现计时更新操作的例子，与大家共勉，有不足的地方还希望大家指出。

-----------xml文件---------------

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >

</LinearLayout>

--------------Activity中的代码---------------------

package com.jzscme.intent;

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

public class Handler_demoActivity extends Activity {

private TextView time;

// 设置消息编号
private static final int UPDATE_TIME = 0;
private static final int UPDATE_SUCC = 1;

//定义用于计时的变量
private int showTime = 0;
//定义是否运行的标志
private boolean isrunning = false;

// 定义handler对象
Handler handler = new Handler() {
@Override
public void handleMessage(Message msg) {
Bundle b = msg.getData();//获取bundle对象中保存的数据
String name = b.getString("time");
switch (msg.what) {
case UPDATE_TIME:
time.setText("正在更新：" + name);
break;

case UPDATE_SUCC:
time.setText("更新完毕");
break;
}
super.handleMessage(msg);
}

};

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

time = (TextView) findViewById(R.id.time);
//设置按钮监听
((Button) findViewById(R.id.bn)).setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// 点击按钮之后开启线程计时
isrunning = true;
myThread thread = new myThread();
thread.start();
}
});
}

/**
* 更新时间线程
*
* @author Administrator
*
*/
public class myThread extends Thread {
public void run() {
while (isrunning) {
try {
showTime++;//计数器 ++
Bundle bundle = new Bundle();//使用Bundle对象保存计数值
bundle.putString("time", String.valueOf(showTime));

Message msg = new Message();//定义message对象
if (showTime <= 5) {//当计数值小于5时
msg.what = UPDATE_TIME;//设置消息发送的编号
} else {
isrunning = false;
msg.what = UPDATE_SUCC;
}
msg.setData(bundle);
handler.sendMessage(msg);//每隔一秒向handler发送一次消息
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}

}

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