在 Android 中进行网络调用以响应 UI 事件

Question

I am building an Android application that needs to make certain network calls in response to UI events. I am struggling to find an elegant way to send out those calls from a UI callback, though. An AsyncTask isn't really a good fit because all I want to do is just send out the call - any responses responses will be handled by callbacks in my receiver code. Likewise, spawning a new thread just to perform a single network call seems wasteful and bad practice, especially considering that in certain cases there will be many, many calls per second as the user interacts with the UI.

Note: by "network call" what I really mean is sending out some bytes through a UDP DatagramSocket

I thought about having a network TX thread with a "send queue" looping continuously that the UI thread could post messages to, but that would seem an incredible waste of CPU cycles during times when there may be several seconds between when calls need to be made.

I have a feeling that the elegant solution is a combination of the above "looping TX thread" idea, but with lock objects so it doesn't loop unless there's new data to send - but I'm not very experienced with concurrency, locks, and the like, so I'm hoping somebody here can point me in the right direction. Any help would be greatly appreciated. Thanks in advance :)

Answer 1

Fort the backgroundwork you use a ThreadPoolExecutor like this. I use a specialised class for this. You post runnables to the executor.

public class RemoteConnections {

//Variables and constants to manange the threadpool
private final int KEEP_ALIVE_TIME = 1;
private final TimeUnit KEEP_ALIVE_TIME_UNIT = TimeUnit.SECONDS;
private final int NUMBER_OF_CORES = Runtime.getRuntime().availableProcessors();
private ThreadPoolExecutor mThreadpool;

private RemoteRepository(Application application) {
    mApplication = application;
    //initialize the threadpool for networking
    final BlockingQueue<Runnable> mQueue = new LinkedBlockingQueue<Runnable>();
    mThreadpool = new ThreadPoolExecutor(NUMBER_OF_CORES, NUMBER_OF_CORES, KEEP_ALIVE_TIME, KEEP_ALIVE_TIME_UNIT.SECONDS, mQueue);
}


public void loadWhatEver() {

    mThreadpool.execute(new Whatever());
}


private class Whatever implements Runnable {
    public  Whatever(//setup whatever you need perhaps your callback listener) {
        mListener = listener;
    }

    @Override
    public void run() {
        //do your downloading here
        //make the callback to the listener
    }    
}

In the activity or fragment just call remote.loadWhatEver() when the event happens.