使用 HttpClient 时记录请求/响应消息

Question

I have a method that does a POST like below

var response = await client.PostAsJsonAsync(url, entity);

if (response.IsSuccessStatusCode)
{
        // read the response as strongly typed object
        return await response.Content.ReadAsAsync<T>();
}

My question is how can I obtain the actual JSON that got posted from the entity object. I would like to log the JSON that gets POSTED, so it will be nice to have that without me having to do a json serialize myself.

Answer 1

An example of how you could do this:

Some notes:

• LoggingHandler intercepts the request before it handles it to HttpClientHandler which finally writes to the wire.

• PostAsJsonAsync extension internally creates an ObjectContent and when ReadAsStringAsync() is called in the LoggingHandler , it causes the formatter inside ObjectContent to serialize the object and that's the reason you are seeing the content in json.

Logging handler:

public class LoggingHandler : DelegatingHandler
{
    public LoggingHandler(HttpMessageHandler innerHandler)
        : base(innerHandler)
    {
    }

    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        Console.WriteLine("Request:");
        Console.WriteLine(request.ToString());
        if (request.Content != null)
        {
            Console.WriteLine(await request.Content.ReadAsStringAsync());
        }
        Console.WriteLine();

        HttpResponseMessage response = await base.SendAsync(request, cancellationToken);

        Console.WriteLine("Response:");
        Console.WriteLine(response.ToString());
        if (response.Content != null)
        {
            Console.WriteLine(await response.Content.ReadAsStringAsync());
        }
        Console.WriteLine();

        return response;
    }
}

Chain the above LoggingHandler with HttpClient :

HttpClient client = new HttpClient(new LoggingHandler(new HttpClientHandler()));
HttpResponseMessage response = client.PostAsJsonAsync(baseAddress + "/api/values", "Hello, World!").Result;

Output:

Request:
Method: POST, RequestUri: 'http://kirandesktop:9095/api/values', Version: 1.1, Content: System.Net.Http.ObjectContent`1[
[System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]], Headers:
{
  Content-Type: application/json; charset=utf-8
}
"Hello, World!"

Response:
StatusCode: 200, ReasonPhrase: 'OK', Version: 1.1, Content: System.Net.Http.StreamContent, Headers:
{
  Date: Fri, 20 Sep 2013 20:21:26 GMT
  Server: Microsoft-HTTPAPI/2.0
  Content-Length: 15
  Content-Type: application/json; charset=utf-8
}
"Hello, World!"

Answer 2

See http://mikehadlow.blogspot.com/2012/07/tracing-systemnet-to-debug-http-clients.html

To configure a System.Net listener to output to both the console and a log file, add the following to your assembly configuration file:

<system.diagnostics>
  <trace autoflush="true" />
  <sources>
    <source name="System.Net">
      <listeners>
        <add name="MyTraceFile"/>
        <add name="MyConsole"/>
      </listeners>
    </source>
  </sources>
  <sharedListeners>
    <add
      name="MyTraceFile"
      type="System.Diagnostics.TextWriterTraceListener"
      initializeData="System.Net.trace.log" />
    <add name="MyConsole" type="System.Diagnostics.ConsoleTraceListener" />
  </sharedListeners>
  <switches>
    <add name="System.Net" value="Verbose" />
  </switches>
</system.diagnostics>

Answer 3

Network tracing also available for next objects (see article on msdn )

• System.Net.Sockets Some public methods of the Socket, TcpListener, TcpClient, and Dns classes
• System.Net Some public methods of the HttpWebRequest, HttpWebResponse, FtpWebRequest, and FtpWebResponse classes, and SSL debug information (invalid certificates, missing issuers list, and client certificate errors.)
• System.Net.HttpListener Some public methods of the HttpListener, HttpListenerRequest, and HttpListenerResponse classes.
• System.Net.Cache Some private and internal methods in System.Net.Cache.
• System.Net.Http Some public methods of the HttpClient, DelegatingHandler, HttpClientHandler, HttpMessageHandler, MessageProcessingHandler, and WebRequestHandler classes.
• System.Net.WebSockets.WebSocket Some public methods of the ClientWebSocket and WebSocket classes.

Put the following lines of code to the configuration file:

<configuration>  
  <system.diagnostics>  
    <sources>  
      <source name="System.Net" tracemode="includehex" maxdatasize="1024">  
        <listeners>  
          <add name="System.Net"/>  
        </listeners>  
      </source>  
      <source name="System.Net.Cache">  
        <listeners>  
          <add name="System.Net"/>  
        </listeners>  
      </source>  
      <source name="System.Net.Http">  
        <listeners>  
          <add name="System.Net"/>  
        </listeners>  
      </source>  
      <source name="System.Net.Sockets">  
        <listeners>  
          <add name="System.Net"/>  
        </listeners>  
      </source>  
      <source name="System.Net.WebSockets">  
        <listeners>  
          <add name="System.Net"/>  
        </listeners>  
      </source>  
    </sources>  
    <switches>  
      <add name="System.Net" value="Verbose"/>  
      <add name="System.Net.Cache" value="Verbose"/>  
      <add name="System.Net.Http" value="Verbose"/>  
      <add name="System.Net.Sockets" value="Verbose"/>  
      <add name="System.Net.WebSockets" value="Verbose"/>  
    </switches>  
    <sharedListeners>  
      <add name="System.Net"  
        type="System.Diagnostics.TextWriterTraceListener"  
        initializeData="network.log"  
      />  
    </sharedListeners>  
    <trace autoflush="true"/>  
  </system.diagnostics>  
</configuration>  

Answer 4

最简单的解决方案是使用Wireshark并跟踪 HTTP tcp 流。