初探guava 線程回調

代碼

public class ExecutorFactor {
    /*固定線程池數量，MoreExecutors只是爲原有的線程池作代理而已，且包裝成ListeningExecutorService 這種類型
，下面在submit才能返回ListenableFuture 類型的future*/
    private static ListeningExecutorService EXECUTOR_SERVICE = MoreExecutors.listeningDecorator(Executors.newCachedThreadPool());
    public static void exec(final FutureService objService, final Object... args) {
        // 異步處理
        ListenableFuture<Object> future = EXECUTOR_SERVICE.submit(
                new Callable<Object>() {
                    public Object call() throws Exception {
                        Object o = objService.handler(args);
                        return o;
                    }
                });


        Futures.addCallback(future,new FutureCallback<Object>() {
            @Override
            public void onSuccess(Object o) {
                // TODO 成功處理
                objService.onSuccess(o, args);
            }

            @Override
            public void onFailure(Throwable throwable) {
                // TODO 失敗處理
                objService.onFailure(throwable, args);
            }
        },EXECUTOR_SERVICE);
    }
}

這裏咱們不妨看下Futures 是如何添加listener 的，點進去

public static <V> void addCallback(
      final ListenableFuture<V> future,
      final FutureCallback<? super V> callback,
    //。。。
    這裏咱們看下CallbackListener這個類
    future.addListener(new CallbackListener<V>(future, callback), executor);
  }


private static final class CallbackListener<V> implements Runnable {
   //發現是個Runnable 類型的類，那麼主要看它的run方法
    @Override
    public void run() {
      final V value;
      try {
        value = getDone(future);
      } catch (ExecutionException e) {
        //若是發生異常就調用異常回調
        callback.onFailure(e.getCause());
        return;
      } catch (RuntimeException e) {
        callback.onFailure(e);
        return;
      } catch (Error e) {
        callback.onFailure(e);
        return;
      }
  //若是正常就調用正常回調
      callback.onSuccess(value);
    }

   
  }