你的位置:首页 > 操作系统

[操作系统]android 进程/线程管理(三)


Thread,Looper的组合是非常常见的组合方式。

Looper可以是和线程绑定的,或者是main looper的一个引用。

下面看看具体app层的使用。

首先定义thread:

package com.joyfulmath.androidstudy.thread;import com.joyfulmath.androidstudy.TraceLog;import android.os.Bundle;import android.os.Handler;import android.os.Looper;import android.os.Message;public class MyLoopThread extends Thread {      private Looper myLooper = null;  private MyHandler mHandler = null;  public MyLoopThread()  {    super();  }    @Override  public void run() {    TraceLog.i("MyLoopThread looper prepare");    Looper.prepare();//    myLooper = Looper.getMainLooper(); /*using this can be set as main handler*/    myLooper = Looper.myLooper();    mHandler = new MyHandler(myLooper);    TraceLog.i("MyLoopThread looper loop");    Looper.loop();  }      public void doAction(int index,String params)  {    if(index>0 && index <=3)    {      Message msg = mHandler.obtainMessage(index);      Bundle bundle = new Bundle();      bundle.putString("key", params);      msg.setData(bundle);      mHandler.sendMessage(msg);    }    else    {      TraceLog.w(index+"");    }  }    public static class MyHandler extends Handler{        public MyHandler()    {      super();    }        public MyHandler(Looper loop)    {      super(loop);    }        /*make sure that the looper is main or not     *so you can update UI or send main handler to do it.     * */    @Override    public void handleMessage(Message msg) {      Bundle bundle = msg.getData();      String params = bundle.getString("key");      TraceLog.i(params);      switch(msg.what)      {      case ThreadConstant.INDEX_1:        TraceLog.d("INDEX_1");        break;      case ThreadConstant.INDEX_2:        TraceLog.d("INDEX_2");        break;      case ThreadConstant.INDEX_3:        TraceLog.d("INDEX_3");        break;        }    }  }}

上面这个MyLoopThread类把,hangler,looper,thread融合在一起了,我们看看关键的地方:

  @Override  public void run() {    TraceLog.i("MyLoopThread looper prepare");    Looper.prepare();//    myLooper = Looper.getMainLooper(); /*using this can be set as main handler*/    myLooper = Looper.myLooper();    mHandler = new MyHandler(myLooper);    TraceLog.i("MyLoopThread looper loop");    Looper.loop();  }

 

如上,Thread只在说一件是,消息循环。而且可以发送消息到主线程来处理。

如果MyLoopThread里面定义两个handler,会不会有冲突呢?

我们用代码试试看。

我们修改下run以及添加doaction2:

@Override  public void run() {    TraceLog.i("MyLoopThread looper prepare");    Looper.prepare();//    myLooper = Looper.getMainLooper(); /*using this can be set as main handler*/    myLooper = Looper.myLooper();    mHandler = new MyHandler(myLooper);    mHandler2 = new Handler(myLooper){      @Override      public void handleMessage(Message msg) {        Bundle bundle = msg.getData();        String params = bundle.getString("key");        TraceLog.i("Handler2 "+params);        switch(msg.what)        {        case ThreadConstant.INDEX_1:          TraceLog.d("Handler2 INDEX_1");          break;        case ThreadConstant.INDEX_2:          TraceLog.d("Handler2 INDEX_2");          break;        case ThreadConstant.INDEX_3:          TraceLog.d("Handler2 INDEX_3");          break;          }      }                };    TraceLog.i("MyLoopThread looper loop");    Looper.loop();  }

  public void doAction2(int index,String params)  {    if(index>0 && index <=3)    {      Message msg = mHandler2.obtainMessage(index);      Bundle bundle = new Bundle();      bundle.putString("key", params);      msg.setData(bundle);      mHandler2.sendMessage(msg);    }    else    {      TraceLog.w(index+"");    }  }

08-03 17:04:40.679: I/MyLoopThread(25483): run: MyLoopThread looper prepare [at (MyLoopThread.java:22)]08-03 17:04:40.679: I/MyLoopThread(25483): run: MyLoopThread looper loop [at (MyLoopThread.java:50)]08-03 17:04:40.769: I/Timeline(25483): Timeline: Activity_idle id: android.os.BinderProxy@224def46 time:14167575908-03 17:04:42.709: I/MyLoopThread$MyHandler(25483): handleMessage: time millseconds one [at (MyLoopThread.java:107)]08-03 17:04:42.709: D/MyLoopThread$MyHandler(25483): handleMessage: INDEX_2 [at (MyLoopThread.java:114)]08-03 17:04:47.299: I/MyLoopThread$1(25483): handleMessage: Handler2 time millseconds two [at (MyLoopThread.java:33)]08-03 17:04:47.299: D/MyLoopThread$1(25483): handleMessage: Handler2 INDEX_2 [at (MyLoopThread.java:40)]08-03 17:04:52.829: I/MyLoopThread$MyHandler(25483): handleMessage: time millseconds one [at (MyLoopThread.java:107)]08-03 17:04:52.829: D/MyLoopThread$MyHandler(25483): handleMessage: INDEX_3 [at (MyLoopThread.java:117)]08-03 17:04:53.479: I/MyLoopThread$MyHandler(25483): handleMessage: time millseconds one [at (MyLoopThread.java:107)]08-03 17:04:53.479: D/MyLoopThread$MyHandler(25483): handleMessage: INDEX_3 [at (MyLoopThread.java:117)]08-03 17:04:54.909: I/MyLoopThread$1(25483): handleMessage: Handler2 time millseconds two [at (MyLoopThread.java:33)]08-03 17:04:54.909: D/MyLoopThread$1(25483): handleMessage: Handler2 INDEX_1 [at (MyLoopThread.java:37)]08-03 17:04:56.309: I/MyLoopThread$1(25483): handleMessage: Handler2 time millseconds two [at (MyLoopThread.java:33)]08-03 17:04:56.309: D/MyLoopThread$1(25483): handleMessage: Handler2 INDEX_3 [at (MyLoopThread.java:43)]

查看消息可以看到, handler很好的处理了消息,没有出现错乱的问题。

我们知道,对于每个thread,looper,messagequeue都是唯一的,那为什么没有出错呢?

我们看看之前在《android 进程/线程管理(一)----消息机制的框架》http://www.cnblogs.com/deman/p/4688054.html

中的looper.loop()

里面有一句:

msg.target.dispatchMessage(msg);

是的,这就是分发和处理消息。而target就是我们的handler。

 

HandlerThread:

对于上面的例子,google提供了一个更方便的解决方案:HandlerThread。

下面是HandlerThread的源码:

@Override  public void run() {    mTid = Process.myTid();    Looper.prepare();    synchronized (this) {      mLooper = Looper.myLooper();      notifyAll();    }    Process.setThreadPriority(mPriority);    onLooperPrepared();    Looper.loop();    mTid = -1;  }

可以看到,handlerThread自己把looper给启动了。

下面是使用handlerthread的代码,比thread,looper更为简单。

package com.joyfulmath.androidstudy.thread;import com.joyfulmath.androidstudy.TraceLog;import android.os.Bundle;import android.os.Handler;import android.os.HandlerThread;import android.os.Looper;import android.os.Message;public class MyHandlerThread extends HandlerThread{  MyHandler myHandler = null;    public MyHandlerThread(String name) {    super(name);  }        @Override  protected void onLooperPrepared() {    super.onLooperPrepared();    myHandler = new MyHandler(getLooper());  }  public void doAction(int index,String params)  {    if(index>0 && index <=3)    {      Message msg = myHandler.obtainMessage(index);      Bundle bundle = new Bundle();      bundle.putString("key", params);      msg.setData(bundle);      myHandler.sendMessage(msg);    }    else    {      TraceLog.w(index+"");    }  }  public static class MyHandler extends Handler{        public MyHandler()    {      super();    }        public MyHandler(Looper loop)    {      super(loop);    }        /*make sure that the looper is main or not     *so you can update UI or send main handler to do it.     * */    @Override    public void handleMessage(Message msg) {      Bundle bundle = msg.getData();      String params = bundle.getString("key");      TraceLog.i(params);      switch(msg.what)      {      case ThreadConstant.INDEX_1:        TraceLog.d("INDEX_1");        break;      case ThreadConstant.INDEX_2:        TraceLog.d("INDEX_2");        break;      case ThreadConstant.INDEX_3:        TraceLog.d("INDEX_3");        break;        }    }  }}

  private void initView() {    ...        btnStart3 = (Button) findViewById(R.id.thread_start_id3);    btnStart3.setOnClickListener(new OnClickListener() {            @Override      public void onClick(View v) {        myHandlerThread.doAction((int)(Math.random()*3)+1, "handlerthread time millseconds");      }    });  }

以上是启动handlerthread的代码。

 

IntentService:

我们可以看看源码:

intentservice 本质上就是 service + handlerthread的组成方式!

public abstract class IntentService extends Service {  private volatile Looper mServiceLooper;  private volatile ServiceHandler mServiceHandler;  private String mName;  private boolean mRedelivery;  private final class ServiceHandler extends Handler {    public ServiceHandler(Looper looper) {      super(looper);    }    @Override    public void handleMessage(Message msg) {      onHandleIntent((Intent)msg.obj);      stopSelf(msg.arg1);    }  }  /**   * Creates an IntentService. Invoked by your subclass's constructor.   *   * @param name Used to name the worker thread, important only for debugging.   */  public IntentService(String name) {    super();    mName = name;  }  /**   * Sets intent redelivery preferences. Usually called from the constructor   * with your preferred semantics.   *   * <p>If enabled is true,   * {@link #onStartCommand(Intent, int, int)} will return   * {@link Service#START_REDELIVER_INTENT}, so if this process dies before   * {@link #onHandleIntent(Intent)} returns, the process will be restarted   * and the intent redelivered. If multiple Intents have been sent, only   * the most recent one is guaranteed to be redelivered.   *   * <p>If enabled is false (the default),   * {@link #onStartCommand(Intent, int, int)} will return   * {@link Service#START_NOT_STICKY}, and if the process dies, the Intent   * dies along with it.   */  public void setIntentRedelivery(boolean enabled) {    mRedelivery = enabled;  }  @Override  public void onCreate() {    // TODO: It would be nice to have an option to hold a partial wakelock    // during processing, and to have a static startService(Context, Intent)    // method that would launch the service & hand off a wakelock.    super.onCreate();    HandlerThread thread = new HandlerThread("IntentService[" + mName + "]");    thread.start();    mServiceLooper = thread.getLooper();    mServiceHandler = new ServiceHandler(mServiceLooper);  }  @Override  public void onStart(Intent intent, int startId) {    Message msg = mServiceHandler.obtainMessage();    msg.arg1 = startId;    msg.obj = intent;    mServiceHandler.sendMessage(msg);  }  /**   * You should not override this method for your IntentService. Instead,   * override {@link #onHandleIntent}, which the system calls when the IntentService   * receives a start request.   * @see android.app.Service#onStartCommand   */  @Override  public int onStartCommand(Intent intent, int flags, int startId) {    onStart(intent, startId);    return mRedelivery ? START_REDELIVER_INTENT : START_NOT_STICKY;  }  @Override  public void onDestroy() {    mServiceLooper.quit();  }  /**   * Unless you provide binding for your service, you don't need to implement this   * method, because the default implementation returns null.   * @see android.app.Service#onBind   */  @Override  public IBinder onBind(Intent intent) {    return null;  }  /**   * This method is invoked on the worker thread with a request to process.   * Only one Intent is processed at a time, but the processing happens on a   * worker thread that runs independently from other application logic.   * So, if this code takes a long time, it will hold up other requests to   * the same IntentService, but it will not hold up anything else.   * When all requests have been handled, the IntentService stops itself,   * so you should not call {@link #stopSelf}.   *   * @param intent The value passed to {@link   *        android.content.Context#startService(Intent)}.   */  protected abstract void onHandleIntent(Intent intent);}

IntentService

我们首先看onCreate:

  public void onCreate() {    // TODO: It would be nice to have an option to hold a partial wakelock    // during processing, and to have a static startService(Context, Intent)    // method that would launch the service & hand off a wakelock.    super.onCreate();    HandlerThread thread = new HandlerThread("IntentService[" + mName + "]");    thread.start();    mServiceLooper = thread.getLooper();    mServiceHandler = new ServiceHandler(mServiceLooper);  }

开启了一个handlerthread,并且初始化mServiceHandler,

mServiceHandler就是一个普通的handler,只是把消息处理给了onHandleIntent

    public void handleMessage(Message msg) {      onHandleIntent((Intent)msg.obj);      stopSelf(msg.arg1);    }

所以intentservice实例就需要实现onHandleIntent方法,来处理消息。

一下是intentservice使用的一个demo:

package com.joyfulmath.androidstudy.thread;import com.joyfulmath.androidstudy.TraceLog;import android.app.IntentService;import android.content.Intent;public class MyIntentService extends IntentService {  public MyIntentService() {    super("MyIntentService");  }        @Override  public void onCreate() {    super.onCreate();    TraceLog.i();  }  @Override  protected void onHandleIntent(Intent intent) {    TraceLog.i();    doAction(intent);  }  @Override  public void onDestroy() {    super.onDestroy();    TraceLog.i();  }    private void doAction(Intent intent)  {    String params = intent.getStringExtra("key");    TraceLog.i(params);    int index = intent.getIntExtra("index", -1);    TraceLog.i(index+"");  }}

MyIntentService

可以看下log:

导出的log,没有tid,所以上传了图片。可以看到onHandleIntent运行在工作线程里面。

IntentService会在处理完了以后,直接destory掉。