java - Guava ListenableFuture 找不到源对象失败

Question

当使用 Guava 的 ListenableFuture 时，如何知道失败的任务。示例

FutureCallback<AsyncHTTPResponse> future = new FutureCallback<AsyncHTTPResponse>() {
  @Override
  public void onFailure(Throwable arg0)
  {
     // In this block I do not know who succeeded. We could create custom 
     // exceptions and put the object in there, but what if we are not
     // directly causing the exception. Seems like there should be an easy
     // way to get the callable task that failed to produce a success result
  }

  @Override
  public void onSuccess(AsyncHTTPResponse arg0)
  {
    // In this block I know the original object that succeded
  }
};

因此，在这个示例中，我找不到给定 URL 来尝试通过 http 获取一些数据的可调用函数。因此失败者不知道哪个 URL 失败了。当然有一些解决方法，例如在表中记录 futures 和 url，但是有没有更简洁的方法来使用框架来为您做到这一点？

Answer 1

我通常看到的解决方案是为每个请求创建一个新的回调实例:

final URL url = ...;
ListenableFuture<AsyncHTTPResponse> future = makeRequest(url);
addCallback(future, new FutureCallback<AsyncHTTPResponse>() {
  @Override
  public void onFailure(Throwable e)
  {
    // do something with url
  }

  ...
});