Android架构分析之Handler分析（一）

作者：刘昊昱 

博客：http://blog.csdn.net/liuhaoyutz

本文介绍了一个使用Handler的Android应用程序，通过该程序，我们可以了解Handler的基本用法。该程序运行效果如下：

点击Button1按钮后，运行效果如下：

点击Button2按钮后，运行效果如下：

下面我们来看这个程序代码。

主程序TestHandlerActivity.java内容如下：

package com.haoyu.testHandler;

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 TestHandlerActivity extends Activity implements OnClickListener{
	TextView textView;
	
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Button button1 = (Button) findViewById(R.id.button1);    
        Button button2 = (Button) findViewById(R.id.button2);
        textView = (TextView) findViewById(R.id.textView);
        
        button1.setOnClickListener(this);
        button2.setOnClickListener(this);
    }
    
	public Handler handler =new Handler(){

		@Override
		public void handleMessage(Message msg) {
			// TODO Auto-generated method stub
			super.handleMessage(msg);
			if(msg.what == 1)
				textView.setText("Button1 is clicked!");
			else if(msg.what == 2)
				textView.setText("Button2 is clicked!");
			else
				textView.setText("Unknown message!");
		}    	
    };

	@Override
	public void onClick(View v) {
		// TODO Auto-generated method stub
		int id = v.getId();
		Message message = new Message();
	
		if(id == R.id.button1)
		{
			 message.what = 1;
			 handler.sendMessage(message);
		}
		if(id == R.id.button2)
		{
			message.what = 2;
			handler.sendMessage(message);
		}
	}
}

主布局文件main.xml内容如下：

<?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" >"
    
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:paddingTop="60dp"
        android:textSize="20dp"
        android:gravity="center"
        android:id="@+id/textView"
        android:text="@string/prompt"
        />
    
    <LinearLayout 
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:gravity="center"
        android:orientation="horizontal" >
        <Button
	        android:layout_width="wrap_content"
	        android:layout_height="wrap_content"
	        android:text="@string/Button1"
	        android:id="@+id/button1" />       
        
	    <Button
	        android:layout_width="wrap_content"
	        android:layout_height="wrap_content"
	        android:text="@string/Button2"
	        android:id="@+id/button2" />       
    </LinearLayout>

</LinearLayout>

Android架构分析之Handler分析（一）,,5-wow.com