在捕获异步回调抛出的异常 [英] Catching an exception thrown in an asynchronous callback

问题描述

我有，需要一个回调参数异步执行的方法，但catch块似乎没有再追由同步调用（ this.Submit 指的是同步的方法）。

I have a method that takes a callback argument to execute asynchronously, but the catch block doesn't seem to be catching any exceptions thrown by the synchronous call (this.Submit refers to a synchronous method).

public void Submit(FileInfo file, AnswerHandler callback)
{
    SubmitFileDelegate submitDelegate = new SubmitFileDelegate(this.Submit);
    submitDelegate.BeginInvoke(file, (IAsyncResult ar) =>
    {
        string result = submitDelegate.EndInvoke(ar);
        callback(result);
    }, null);
}

有没有办法赶上了新的线程抛出的异常，并将其发送到原来的线程？此外，这是正确的方式来处理异步异常？我写我的code，以便它可以这样调用（假设异常的问题是固定的）：

Is there a way to catch the exception thrown by the new thread and send it to the original thread? Also, is this the "proper" way to handle async exceptions? I wrote my code so it could be called like this (assuming the exception issue is fixed):

try
{
    target.Submit(file, (response) =>
    {
        // do stuff
    });
}
catch (Exception ex)
{
    // catch stuff
}

但有这样做更适当的或优雅的方式？

but is there a more proper or elegant way to do this?

推荐答案

这是不是一个最佳实践的解决方案，但我认为这是一个简单的，应该工作。

This is not a 'best practice' solution, but I think it's a simple one that should work.

而不必定义为

private delegate string SubmitFileDelegate(FileInfo file);

将其定义为

private delegate SubmitFileResult SubmitFileDelegate(FileInfo file);

和定义SubmitFileResult如下：

and define the SubmitFileResult as follows:

public class SubmitFileResult
{
    public string Result;
    public Exception Exception;
}

然后，实际执行文件提交（在问题未显示）的方法应该是这样定义的：

Then, the method that actually does the file submission (not shown in the question) should be defined like this:

private static SubmitFileResult Submit(FileInfo file)
{
    try
    {
        var submissionResult = ComplexSubmitFileMethod();

        return new SubmitFileResult { Result = submissionResult };
    }
    catch (Exception ex)
    {
        return new SubmitFileResult {Exception = ex, Result = "ERROR"};
    }
}

这样，您将检查结果对象，看它是否有结果，或者例外字段集，并采取相应的行动。

This way, you'll examine the result object, see if it has the Result or the Exception field set, and act accordingly.

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