WebException 如何通过正文获得整个响应？

Question

在 WebException 中，我看不到 GetResponse 的正文。这是我在 C# 中的代码：

try {                
  return GetResponse(url + "." + ext.ToString(), method, headers, bodyParams);
} catch (WebException ex) {
    switch (ex.Status) {
      case WebExceptionStatus.ConnectFailure:
         throw new ConnectionException();                        
     case WebExceptionStatus.Timeout:
         throw new RequestTimeRanOutException();                     
     case WebExceptionStatus.NameResolutionFailure:
         throw new ConnectionException();                        
     case WebExceptionStatus.ProtocolError:
          if (ex.Message == "The remote server returned an error: (401) unauthorized.") {
              throw new CredentialsOrPortalException();
          }
          throw new ProtocolErrorExecption();                    
     default:
          throw;
    }

我看到标题但我没有看到正文。这是 Wireshark 针对请求的输出：

POST /api/1.0/authentication.json HTTP/1.1    
Content-Type: application/x-www-form-urlencoded    
Accept: application/json    
Host: nbm21tm1.teamlab.com    
Content-Length: 49    
Connection: Keep-Alive    

userName=XXX&password=YYYHTTP/1.1 500 Server error    
Cache-Control: private, max-age=0    
Content-Length: 106    
Content-Type: application/json; charset=UTF-8    
Server: Microsoft-IIS/7.5    
X-AspNet-Version: 2.0.50727    
X-Powered-By: ASP.NET    
X-Powered-By: ARR/2.5

Date: Mon, 06 Aug 2012 12:49:41 GMT    
Connection: close    

{"count":0,"startIndex":0,"status":1,"statusCode":500,"error":{"message":"Invalid username or password."}}

是否有可能在 WebException 中看到消息文本？ 谢谢。

Answer 1

var resp = new StreamReader(ex.Response.GetResponseStream()).ReadToEnd();

dynamic obj = JsonConvert.DeserializeObject(resp);
var messageFromServer = obj.error.message;

Answer 2

try {
 WebClient client = new WebClient();
 client.Encoding = Encoding.UTF8;
 string content = client.DownloadString("https://sandiegodata.atlassian.net/wiki/pages/doaddcomment.action?pageId=524365");
 Console.WriteLine(content);
 Console.ReadKey();
} catch (WebException ex) {
 var resp = new StreamReader(ex.Response.GetResponseStream()).ReadToEnd();
 Console.WriteLine(resp);
 Console.ReadKey();
}

Answer 3

这只改进了现有的答案。我编写了一个方法，它使用增强的消息处理投掷/重新投掷的细节，其中包括响应正文：

这是我的代码（在 Client.cs 中）：

/// <summary>
///     Tries to rethrow the WebException with the data from the body included, if possible. 
///     Otherwise just rethrows the original message.
/// </summary>
/// <param name="wex">The web exception.</param>
/// <exception cref="WebException"></exception>
/// <remarks>
///     By default, on protocol errors, the body is not included in web exceptions. 
///     This solutions includes potentially relevant information for resolving the
///     issue.
/// </remarks>
private void ThrowWithBody(WebException wex) {
    if (wex.Status == WebExceptionStatus.ProtocolError) {
        string responseBody;
        try {
            //Get the message body for rethrow with body included
            responseBody = new StreamReader(wex.Response.GetResponseStream()).ReadToEnd();

        } catch (Exception) {
            //In case of failure to get the body just rethrow the original web exception.
            throw wex;
        }

        //include the body in the message
        throw new WebException(wex.Message + $" Response body: '{responseBody}'", wex, wex.Status, wex.Response);
    }

    //In case of non-protocol errors no body is available anyway, so just rethrow the original web exception.
    throw wex;
}

您在 catch 子句中使用它，就像 OP 显示的那样：

//Execute Request, catch the exception to eventually get the body
try {
    //GetResponse....
    }
} catch (WebException wex) {
    if (wex.Status == WebExceptionStatus.ProtocolError) {
        ThrowWithBody(wex);
    }

    //otherwise rethrow anyway
    throw;
}

Answer 4

我没有看到using 语句的任何答案，也没有看到async 的任何用途。

public static class WebExceptionExtensions
{
    public static string GetResponseBody(this WebException webException)
    {
        if (webException.Status == WebExceptionStatus.ProtocolError)
        {
            try
            {
                using (var stream = webException.Response.GetResponseStream())
                {
                    using (var reader = new StreamReader(stream))
                    {
                        string msg = reader.ReadToEnd();
                        if (string.IsNullOrEmpty(msg) && webException.Response is HttpWebResponse response)
                            msg = $"{response.StatusDescription} ({(int)response.StatusCode})"; // provide some error message if not found

                        return msg;
                    }
                }
            }
            catch (WebException) // we tried
            {
                return string.Empty;
            }
        }
        else
        {
            return string.Empty;
        }
    }

    public static async Task<string> GetResponseBodyAsync(this WebException webException)
    {
        if (webException.Status == WebExceptionStatus.ProtocolError)
        {
            try
            {
                using (var stream = webException.Response.GetResponseStream())
                {
                    using (var reader = new StreamReader(stream))
                    {
                        string msg = await reader.ReadToEndAsync();
                        if (string.IsNullOrEmpty(msg) && webException.Response is HttpWebResponse response)
                            msg = $"{response.StatusDescription} ((int){response.StatusCode})"; // provide some error message if not found

                        return msg;
                    }
                }
            }
            catch (WebException) //  we tried
            {
                return string.Empty;
            }
        }
        else
        {
            return string.Empty;
        }
    }
}

现在，每当我们捕获 WebExceptions 时，就很容易获得响应体。

try 
{
    // Do work here...
}
catch (WebException we)
{
    Console.WriteLine(we.GetResponseBody()); // synchronous
    Console.WriteLine(await we.GetResponseBodyAsync()); // or asynchronous
}
catch (Exception e)
{
    throw new Exception("Unexpected error occured", e);
}