IntentService与Service的区别

转自:https://www.cnblogs.com/denluoyia/p/5997452.html

IntentService是继承并处理异步请求的一个类,在IntentService内有一个工作线程来处理耗时操作,启动IntentService的方式和启动传统的Service一样,同时,当任务执行完后,IntentService会自动停止,而不需要我们手动去控制或stopSelf()。另外,可以启动IntentService多次,而每一个耗时操作会以工作队列的方式在IntentService的onHandleIntent回调方法中执行,并且,每次只会执行一个工作线程,执行完第一个再执行第二个,以此类推。

 

先来看一下IntentService类的源码:

复制代码
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(); //开启一个工作线程

        mServiceLooper = thread.getLooper(); //单独的消息队列
        mServiceHandler = new ServiceHandler(mServiceLooper); 
 }
复制代码

 

 

定义一个IntentService的子类:

复制代码
public class MIntentService extends IntentService {

    public MIntentService(){
        super("MIntentService");
    }

    /**
     * Creates an IntentService.  Invoked by your subclass's constructor.
     * @param name Used to name the worker thread, important only for debugging.
     */
    public MIntentService(String name) {
        super(name);
    }

    @Override
    public void onCreate() {
        Log.e("MIntentService--", "onCreate");
        super.onCreate();
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.e("MIntentService--", "onStartCommand");
        return super.onStartCommand(intent, flags, startId);
    }

    @Override
    protected void onHandleIntent(Intent intent) {
        Log.e("MIntentService--", Thread.currentThread().getName() + "--" + intent.getStringExtra("info") );
        for(int i = 0; i < 100; i++){ //耗时操作
            Log.i("onHandleIntent--",  i + "--" + Thread.currentThread().getName());
        }
    }

    @Override
    public void onDestroy() {
        Log.e("MIntentService--", "onDestroy");
        super.onDestroy();
    }
}
复制代码

 

开启IntentService服务:

 public void intentClick(View v){
        Intent intent = new Intent(this, MIntentService.class);
        intent.putExtra("info", "good good study");
        startService(intent);
 }

 

点击按钮之后输出结果为(过滤log.e):

10-25 16:54:58.852  27135-27135/com.example.lenovo.myintentservicedemo E/MIntentService--﹕ onCreate
10-25 16:54:58.852  27135-27135/com.example.lenovo.myintentservicedemo E/MIntentService--﹕ onStartCommand
10-25 16:54:58.856  27135-27354/com.example.lenovo.myintentservicedemo E/MIntentService--﹕ IntentService[MIntentService]--good good study
10-25 16:54:58.879  27135-27135/com.example.lenovo.myintentservicedemo E/MIntentService--﹕ onDestroy

  Intent服务开启后,执行完onHandleIntent里面的任务就自动销毁结束,通过打印的线程名称可以发现是新开了一个线程来处理耗时操作的,即是耗时操作也可以被这个线程管理和执行,同时不会产生ANR的情况。

posted @ 2019-03-04 22:15  随风飘落的雨滴  阅读(47)  评论(0编辑  收藏