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);
}
}
public IntentService(String name) {
super();
mName = name;
}
public void setIntentRedelivery(boolean enabled) {
mRedelivery = enabled;
}
@Override
public void onCreate() {
super.onCreate();
HandlerThread thread = new HandlerThread("IntentService[" + mName + "]");
thread.start();
mServiceLooper = thread.getLooper();
mServiceHandler = new ServiceHandler(mServiceLooper);
}
@Override
public void onStart(@Nullable Intent intent, int startId) {
Message msg = mServiceHandler.obtainMessage();
msg.arg1 = startId;
msg.obj = intent;
mServiceHandler.sendMessage(msg);
}
@Override
public int onStartCommand(@Nullable Intent intent, int flags, int startId) {
onStart(intent, startId);
return mRedelivery ? START_REDELIVER_INTENT : START_NOT_STICKY;
}
@Override
public void onDestroy() {
mServiceLooper.quit();
}
@Override
@Nullable
public IBinder onBind(Intent intent) {
return null;
}
@WorkerThread
protected abstract void onHandleIntent(@Nullable Intent intent);
}
所有的源码都在这里,仅仅几十行而已,咱们看看内部他都作了什么操做呢?
1. 构造函数,一个参数的构造以下java
public IntentService(String name) {
super();
mName = name;
//传入了一个名字,这个名字是在建立一个HandlerThread ,为该线程取名用的,至于HandlerThread 是个什么东西,咱们现放在这里后面再讲
/*new HandlerThread("IntentService[" + mName + "]"); */
}
@Override
public void onCreate() {
super.onCreate();
HandlerThread thread = new HandlerThread("IntentService[" + mName + "]");
thread.start();
mServiceLooper = thread.getLooper();
mServiceHandler = new ServiceHandler(mServiceLooper);
}
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);
}
}
@WorkerThread
protected abstract void onHandleIntent(@Nullable Intent intent);
@Override
public void onStart(@Nullable Intent intent, int startId) {
Message msg = mServiceHandler.obtainMessage();
msg.arg1 = startId;
msg.obj = intent;
mServiceHandler.sendMessage(msg);
}
@Override
public int onStartCommand(@Nullable Intent intent, int flags, int startId) {
onStart(intent, startId);
return mRedelivery ? START_REDELIVER_INTENT : START_NOT_STICKY;
}
5.销毁
mServiceLooper.quit(); 这个是什么呢?
mServiceLooper = thread.getLooper(); mServiceLooper 是根据当HandlerThread的工做线程获取到的 一个 Looper对象,在销毁时中止web
@Override
public void onDestroy() {
mServiceLooper.quit();
}
整个service的流程如上所讲几个小点,咱们发现其实IntentService是一个用来处理异步任务而且处理完任务以后会自行退出的service(handleMessage 里面回调 onHandleIntent以后调用了 stopSelf(msg.arg1);)。异步