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。