Android学习笔记8——Handler使用

1.Handler基本使用和Runnable

2.Handler的真正的线程使用方法

 

 

1.Handler基本使用和Runnable

1.使用了handler插入线程

2.线程启动后进行sleep后发送msg

3.handler处理msg，然后再插入线程

4.重复2和3

ps:使用的是异步消息处理机制（发送消息，与处理是分开的）

class myButtonListener implements OnClickListener{@Overridepublic void onClick(View arg0) {// TODO Auto-generated method stubFirstBar.setVisibility(View.VISIBLE);UpdateBarHandler.post(updateThread);}}Handler UpdateBarHandler = new Handler(){/* (non-Javadoc)* @see android.os.Handler#handleMessage(android.os.Message)*/@Overridepublic void handleMessage(Message msg) {// TODO Auto-generated method stub//super.handleMessage(msg);FirstBar.setProgress(msg.arg1);if ( msg.arg1 == FirstBar.getMax()){FirstBar.setVisibility(View.GONE); UpdateBarHandler.removeCallbacks(updateThread);}else{FirstBar.setSecondaryProgress(msg.arg1+10);UpdateBarHandler.post(updateThread);}}};Runnable updateThread = new Runnable(){/* (non-Javadoc)* @see java.lang.Runnable#run()*/int i = 0;@Overridepublic void run() {// TODO Auto-generated method stubSystem.out.println("UpdateThread");i = i + 10;Message msg = UpdateBarHandler.obtainMessage();msg.arg1 = i;try{Thread.sleep(1000);}catch (InterruptedException e){e.printStackTrace();}//UpdateBarHandler.postDelayed(updateThread, 1000);UpdateBarHandler.sendMessage(msg);}}; 

 

2.Handler的真正的线程使用方法

1）使用handler.post 方法并不是启动新的线程去执行runnable的run方法

可以通过过打印线程ID和线程NAME去确认

 

System.out.println("UpdateThreadID -->"+Thread.currentThread().getId());System.out.println("UpdateThreadName-->"+Thread.currentThread().getName()); 

2）标准的java启动新线程方法

用Thread新建一个对象，插入runnable做参数

然后调用Thread的start函数进行

Thread t = new Thread(updateThread);t.start(); 

3）Android的启动新线程方法

 class myButtonListener implements OnClickListener{@Overridepublic void onClick(View arg0) {// TODO Auto-generated method stub// 生成一个intent 对象if (!useToastInsteadWin){String strFactor1 = factor1.getText().toString();String strFactor2 = factor2.getText().toString();Intent intent = new Intent();intent.putExtra("one", strFactor1);intent.putExtra("two", strFactor2);intent.setClass(hello.this, OtherActivity.class);//intent.setClass(hello.this, listAct.class);hello.this.startActivity(intent);}else{FirstBar.setVisibility(View.VISIBLE);//UpdateBarHandler.post(updateThread);HandlerThread handlerThread = new HandlerThread("Handler-Thread");handlerThread.start();//MyHandler myHandler = new MyHandler(handlerThread.getLooper());myHandler = new MyHandler(handlerThread.getLooper());Message msg = myHandler.obtainMessage();msg.sendToTarget();}} }class MyHandler extends Handler{public MyHandler(){}//处理消息队列public MyHandler(Looper looper){super(looper);}/* (non-Javadoc) * @see android.os.Handler#handleMessage(android.os.Message) */@Overridepublic void handleMessage(Message msg) {// TODO Auto-generated method stub//super.handleMessage(msg); System.out.println("MyHandlerID -->"+Thread.currentThread().getId()); System.out.println("MyHandlerName-->"+Thread.currentThread().getName()); //把设置进程条处理放置这里 FirstBar.setProgress(msg.arg1);if ( msg.arg1 == FirstBar.getMax()){//end hereSystem.out.println("MyHandlerID --> FirstBar.setVisibility(View.GONE)" + msg.arg1);//FirstBar.setVisibility(View.GONE);myHandler.removeCallbacks(updateThread);//这句有问题，暂时注销//FirstBar.setVisibility(View.GONE);}else if ( msg.arg1 < FirstBar.getMax()){//get start from hereSystem.out.println("MyHandlerID --> setSecondaryProgress(msg.arg1+10)"+ msg.arg1);FirstBar.setSecondaryProgress(msg.arg1+10);myHandler.post(updateThread);}} Runnable updateThread = new Runnable(){ /* (non-Javadoc) * @see java.lang.Runnable#run() */ int i = 0; @Override public void run() {// TODO Auto-generated method stubSystem.out.println("UpdateThread"); System.out.println("Runnable_UpdateThreadID -->"+Thread.currentThread().getId()); System.out.println("Runnable_UpdateThreadName-->"+Thread.currentThread().getName());i = i + 10;Message msg = myHandler.obtainMessage();msg.arg1 = i;try{Thread.sleep(1000);}catch (InterruptedException e){e.printStackTrace();}myHandler.sendMessage(msg); } }; }

代码中FirstBar.setVisibility(View.GONE);

设置进度条消失的代码还有问题，待以后解决

解决方法，把这句代码放到主线程中就可以，一旦这种关于layout的view变量操作

在新建立的线程，程序就出错，无论是View.VISIBLE，还是GONE

但我还是手动关闭进度条的，那自动是如何，发送信息，回到主线程关闭？？？？

怎么实现，恩，想好了，以后再附上代码

新建立了一个线程，这样即使在下载，也可以反应别的操作