android 进程/线程管理（三）----Thread,Looper / HandlerThread / IntentService

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:141675759
08-03 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。

相关文章：

android 进程/线程管理（二）----关于线程的迷思

android 进程/线程管理（一）----消息机制的框架