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》/article/5234679.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！

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