1、IntentService 是什麼?
IntentService是繼承service的一個非同步類,裡面封裝了Handler和HandlerThread,總共也就100多行程式碼。
2、原始碼分析工作原理
public abstract class IntentService extends Service {
private volatile Looper mServiceLooper;//訊息傳送的looper
private volatile ServiceHandler mServiceHandler;// handler
private String mName;
private boolean mRedelivery;
private final class ServiceHandler extends Handler {
public ServiceHandler(Looper looper) {
super(looper);
}
@Override
public void handleMessage(Message msg) {
//1、接收ServiceHandle發過來的訊息
//2、通過onHandlerIntent()將訊息發出
onHandleIntent((Intent)msg.obj);
//3、服務自己停止
stopSelf(msg.arg1);
}
}
public IntentService(String name) {
super();
mName = name;
}
public void setIntentRedelivery(boolean enabled) {
mRedelivery = enabled;
}
@Override
public void onCreate() {
super.onCreate();
//1、建立子執行緒handlerThread
HandlerThread thread = new HandlerThread("IntentService[" + mName + "]");
thread.start();
//2、獲得 handlerThread裡面的Looper();--->子執行緒
mServiceLooper = thread.getLooper();
//3、根據子執行緒提供的looper ,建立Handler
mServiceHandler = new ServiceHandler(mServiceLooper);
}
@Override
public void onStart(@Nullable Intent intent, int startId) {
Message msg = mServiceHandler.obtainMessage();
msg.arg1 = startId;
msg.obj = intent;
//傳送訊息
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) {
//通過bind的方式開啟IntentService,onHandleIntent無法接受訊息。
return null;
}
@WorkerThread
protected abstract void onHandleIntent(@Nullable Intent intent);
}
複製程式碼