Handler和Looper

最新推荐文章于 2025-08-07 17:42:48 发布

原创最新推荐文章于 2025-08-07 17:42:48 发布 · 241 阅读

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本文介绍了一个使用Android Handler机制实现UI更新的例子。通过创建自定义的Handler、Runnable对象及子线程，文章展示了如何将数据从子线程传递到主线程，并更新界面上的TextView组件。

1. Activity代码

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

public class HandlerActivity extends Activity {

	private Button myButton = null;
	private TextView textView = null;
	private Handler handler = null;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		//在Activit当中有一个默认的Looper的对象，来处理子线程中发送的消息
		myButton = (Button)this.findViewById(R.id.button1);
		textView = (TextView)this.findViewById(R.id.TextView1);
		Looper looper = Looper.myLooper();
		handler = new MyHandler(looper);
		myButton.setOnClickListener(new View.OnClickListener() {
			
			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				new Thread(new MyThread()).start();
			}
		});
	}
	
	//建立子线程
	public class MyThread implements Runnable{

		@Override
		public void run() {
			// TODO Auto-generated method stub
			Message message = Message.obtain();
			message.obj = "gaojiing";
			handler.sendMessage(message);
		}
	}
	
	
	
	public class MyHandler extends Handler{
		
		public MyHandler(){}
		public MyHandler(Looper looper){
			super(looper);
		}
		
		@Override
		public void handleMessage(Message msg) {
			// TODO Auto-generated method stub
			super.handleMessage(msg);
			textView.setText("--obj-->>" + msg.obj.toString());
		}
	}
	
	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.handler, menu);
		return true;
	}

}

2. main.xml文件代码

<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=".HandlerActivity" >

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:text="发送消息" />

    <TextView
        android:id="@+id/TextView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="46dp"
         />

</RelativeLayout>