处理两个WebException的正确

问题描述

我正在尝试处理两个不同的 WebException 。

基本上，它们在调用 WebClient.DownloadFile（string address，string fileName）

$ b后处理
$ b

AFAIK，到目前为止，我有两个我必须处理，两个 WebException 的：

• 远程名称无法解析（即，没有网络连接访问服务器以下载文件）


• （404）文件不包含（即文件不存在于服务器上）

可能有更多，但这是迄今为止我发现最重要的。 / p>

所以我应该如何正确地处理这个问题，因为它们都是 WebException ，但我想处理上述每个案例

这是我迄今为止所做的：

  try 
 {
 using（var client = new WebClient（））
 {
 client.DownloadFile（...）; 
} 
} 
 catch（InvalidOperationException ioEx）
 {
 if（ioEx是WebException）
 {
 if（ioEx.Message.Contains （404）
 {
 // handle 404 
} 
 if（ioEx.Message.Contains（remote name can not）
 {
 //句柄文件不存在
} 
} 
} 
  

正如你所看到的那样，我正在检查消息以查看它是什么类型的WebException，我会假设有更好或更准确的方法来实现？

谢谢

解决方案

根据，你可以按照以下几点做一些事情：

  try 
 {
 //尝试在这里下载文件
} 
 catch（WebException ex）
 {
 if（ ex.Status == WebExceptionStatus.ProtocolError ）
 {
 if（（（HttpWebResponse）ex.Response）.StatusCode == HttpStatusCode.NotFound）
 {
 //处理404这里
} 
} 
 else if（ex.Status == WebExceptionStatus.NameResolutionFailure）
 {
 //句柄名称解析失败
} 
} 
  

我不确定 WebExceptionStatus.NameResolutionFailure 是您的错误看到，但您可以检查抛出的异常，并确定该错误的 WebExceptionStatus 。

I am trying to handle two different WebException's properly.

Basically they are handled after calling WebClient.DownloadFile(string address, string fileName)

AFAIK, so far there are two I have to handle, both WebException's:

• The remote name could not be resolved (i.e. No network connectivity to access server to download file)
• (404) File not nound (i.e. the file doesn't exist on the server)

There may be more but this is what I've found most important so far.

So how should I handle this properly, as they are both WebException's but I want to handle each case above differently.

This is what I have so far:

try
{
    using (var client = new WebClient())
    {
        client.DownloadFile("...");
    }
}
catch(InvalidOperationException ioEx)
{
    if (ioEx is WebException)
    {
        if (ioEx.Message.Contains("404")
        {
            //handle 404
        }
        if (ioEx.Message.Contains("remote name could not")
        {
            //handle file doesn't exist
        }
    }
}

As you can see I am checking the message to see what type of WebException it is. I would assume there is a better or a more precise way to do this?

Thanks

解决方案

Based on this MSDN article, you could do something along the following lines:

try
{
    // try to download file here
}
catch (WebException ex)
{
    if (ex.Status == WebExceptionStatus.ProtocolError)
    {
        if (((HttpWebResponse)ex.Response).StatusCode == HttpStatusCode.NotFound)
        {
            // handle the 404 here
        }
    }
    else if (ex.Status == WebExceptionStatus.NameResolutionFailure)
    {
        // handle name resolution failure
    }
}

I'm not certain that WebExceptionStatus.NameResolutionFailure is the error you are seeing, but you can examine the exception that is thrown and determine what the WebExceptionStatus for that error is.

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