Handler 简单用法

看mars的视频，学的一些代码：

package com.example.handletest;

import java.text.SimpleDateFormat;
import java.util.Date;

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

/**
 * 简单的例子：
 * 包含：
 * 1.一个handler
 * 2.一个线程
 * 两个button通过handler控制：线程进入handler的线程队列
 * 线程进入handler队列后会自动调用run方法运行
 * @author hongyehwy
 */
public class MainActivity extends Activity {

	
	private static final SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
	private Button starButton;
	private Button endButton;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		starButton = (Button)findViewById(R.id.button_satrt);
		starButton.setOnClickListener(new StartListener());
		endButton = (Button)findViewById(R.id.button_end);
		endButton.setOnClickListener(new EndListener());
	}
	
	private Handler myHandler = new Handler();
	
	class StartListener implements OnClickListener{

		@Override
		public void onClick(View v) {
			myHandler.post(myThread);
		}
		
	}
	
	class EndListener implements OnClickListener{

		@Override
		public void onClick(View v) {
			myHandler.removeCallbacks(myThread);
			
			System.out.println("stop");
		}
		
	}
	
	//一个线程变量
	Runnable myThread = new Runnable(){

		@Override
		public void run() {
			System.out.println("thread-"+ Thread.currentThread().getName()+" run @ "+sdf.format(new Date()));
			myHandler.postDelayed(myThread, 3000);
		}
	};	
	
	

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

}

 

demo2：

package com.example.handleandprogressbar;

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

/**
 * 
 * @author hongyehwy
 * 部件
 * 1.两个button，分别控制进度条的前进、停止前进
 * 2.进度条
 * 执行过程：
 * 1.button 通过 handler控制线程的启动，线程启动后增加progressbar的进度,并将增加后的值传递到数据队列
 * 2.handler重写handleMessage方法，从msg中获取当前progressbar的大小，调用progressbar的方法更新progressbar
 * 3.当progressbar的大小 > 100的时候，从线程队列中删除线程
 * 
 */
public class MainActivity extends Activity {
	
	private ProgressBar pb;
	private Button start;
	private Button end;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		pb = (ProgressBar)findViewById(R.id.progressBar);
		start = (Button)findViewById(R.id.button_start);
		start.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				pb.setVisibility(View.VISIBLE);
				progressBarHandler.post(updateThread);
			}
		});
		
		end =  (Button)findViewById(R.id.button_end);
		end.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				progressBarHandler.removeCallbacks(updateThread);
				
			}
		});
		
	}
	
	
	//处理progressBar的Handler
	private Handler progressBarHandler = new Handler(){
		
		@Override
		public void handleMessage(Message msg) {
			super.handleMessage(msg);
			pb.setProgress(msg.arg1);
			progressBarHandler.post(updateThread);
		};
		
	};
	
	//处理progressBar的线程
	private Runnable updateThread = new Runnable() {
		
		int i = 0;
		
		@Override
		public void run() {
			System.out.println("start updateThread ");
			if( i < 100){
				i = i + 10;
				Message msg = progressBarHandler.obtainMessage();
				msg.arg1 = i;
				try{
					Thread.sleep(1000);
				}catch (Exception e) {
				}
				progressBarHandler.sendMessage(msg);
			}else{
				progressBarHandler.removeCallbacks(this);
			}
		}
	};

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

}

 

前面两个demo中，都是在主线程中操作handle对象，并不是实际意义上的异步线程操作。

下面的demo通过HandlerThread获取一个非主线程looper，然后在这个looper中处理这些异步操作。

 

demo3

package com.example.handletest;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.HandlerThread;
import android.os.Looper;
import android.os.Message;
import android.view.Menu;

/**
 * 简单的例子：
 * 包含：
 * 1.一个HandlerThread
 * 2.一个继承自Handler的类，添加带looper参数的构造函数,重载handlerMessage方法
 * 执行过程：
 * 1.通过HandlerThread获得一个非主线程的looper对象，并将这个looper对象分配给Handler对象。
 * 2.获取Handler的msg，填充msg对象（发送异步线程消息消息），并在Handler对象的handleMessage方法中处理这个消息。
 * 
 * @author hongyehwy
 */
public class MainActivity2 extends Activity {
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main2);
		
		System.out.println("activity thread id-->"+Thread.currentThread().getId());
		System.out.println("activity thread name-->"+Thread.currentThread().getName());
		
		HandlerThread hThread = new HandlerThread("Handler Thread");
		hThread.start();
		
		MyHandler myHandler = new MyHandler(hThread.getLooper());
		Message msg = myHandler.obtainMessage();
		Bundle bundle = new Bundle();
		bundle.putString("name", "kate");
		bundle.putString("age", "18");
		msg.setData(bundle);
		
		msg.sendToTarget();
	}
	
	class MyHandler extends Handler{
		
		public MyHandler() {}
		
		public MyHandler(Looper looper) {
			super(looper);
		}
		
		@Override
		public void handleMessage(Message msg) {
			System.out.println("MyHandler thread id-->"+Thread.currentThread().getId());
			System.out.println("MyHandler thread name-->"+Thread.currentThread().getName());
			
			Bundle bundle = msg.getData();
			System.out.println("name = "+bundle.getString("name")+" ; age = "+bundle.getString("age"));
		};
	};

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

}