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

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: [email protected] 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);
}

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
+””);
}
}

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。

 

本文链接:android 进程/线程管理(三)—-Thread,Looper / HandlerThread / IntentService,转载请注明。



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