如果使用 C# 的内容长度 > 7kb，则无法在 WebRequest 上发布

我正在尝试将 Json 发布到我们的网络服务。我的问题是，当我的 request.ContentLength 超过 7kb 时。我将在 request.GetResponse() 处收到 Web 异常 500。但如果我的 request.ContentLength 低于 7kb，我的帖子就会成功发送。

错误信息：

 The remote server returned an error: (500) Internal Server Error.

源代码：

public static string JsonPost(string url, string method, string postData)
{
    Uri address = new Uri(url + method);
    HttpWebRequest request = WebRequest.Create(address) as HttpWebRequest;
    request.Method = "POST";
    request.ContentType = "application/json";
    byte[] byteData = UTF8Encoding.UTF8.GetBytes(postData);
    request.ContentLength = byteData.Length;
    using (Stream postStream = request.GetRequestStream())
    {
        postStream.Write(byteData, 0, byteData.Length);
    }
    try
    {
        using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
        {
            StreamReader reader = new StreamReader(response.GetResponseStream());
            string JsonResponse = reader.ReadToEnd();
            return JsonResponse;
        }
    }
    catch (WebException ex)
    {
        string message = ((System.Net.HttpWebResponse)(ex.Response)).StatusDescription;
        if (message.Contains("busy"))
            return message;
        else
            throw new Exception(message);
    }
}

网页配置：

        <?xml version="1.0"?>

<configuration>
  <appSettings>
    <add key="webpages:Version" value="1.0.0.0"/>
    <add key="ClientValidationEnabled" value="true"/>
    <add key="UnobtrusiveJavaScriptEnabled" value="true"/>
  </appSettings>

  <system.web>
    <httpRuntime executionTimeout="180" maxRequestLength="1048576" useFullyQualifiedRedirectUrl="false" minFreeThreads="8"
    minLocalRequestFreeThreads="4" appRequestQueueLimit="100" enableVersionHeader="true" />

    <compilation debug="true" targetFramework="4.0">
      <assemblies>
        <add assembly="System.Web.Abstractions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.Helpers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.Routing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.Mvc, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.WebPages, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
      </assemblies>
    </compilation>

    <authentication mode="Forms">
      <forms loginUrl="~/Home/" cookieless="AutoDetect" timeout="2880" />
    </authentication>

    <membership>
      <providers>
        <clear/>
        <add name="AspNetSqlMembershipProvider" type="System.Web.Security.SqlMembershipProvider" connectionStringName="ApplicationServices"
             enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="false"
             maxInvalidPasswordAttempts="5" minRequiredPasswordLength="6" minRequiredNonalphanumericCharacters="0" passwordAttemptWindow="10"
             applicationName="/" />
      </providers>
    </membership>

    <profile>
      <providers>
        <clear/>
        <add name="AspNetSqlProfileProvider" type="System.Web.Profile.SqlProfileProvider" connectionStringName="ApplicationServices" applicationName="/" />
      </providers>
    </profile>

    <roleManager enabled="false">
      <providers>
        <clear/>
        <add name="AspNetSqlRoleProvider" type="System.Web.Security.SqlRoleProvider" connectionStringName="ApplicationServices" applicationName="/" />
        <add name="AspNetWindowsTokenRoleProvider" type="System.Web.Security.WindowsTokenRoleProvider" applicationName="/" />
      </providers>
    </roleManager>

    <pages>
      <namespaces>
        <add namespace="System.Web.Helpers" />
        <add namespace="System.Web.Mvc" />
        <add namespace="System.Web.Mvc.Ajax" />
        <add namespace="System.Web.Mvc.Html" />
        <add namespace="System.Web.Routing" />
        <add namespace="System.Web.WebPages"/>
      </namespaces>
    </pages>
  </system.web>

  <system.webServer>
    <security>
      <requestFiltering>
        <requestLimits maxAllowedContentLength="1073741824" />
      </requestFiltering>
    </security>
    <validation validateIntegratedModeConfiguration="false"/>
    <modules runAllManagedModulesForAllRequests="true"/>
  </system.webServer>

  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" />
        <bindingRedirect oldVersion="1.0.0.0-2.0.0.0" newVersion="3.0.0.0" />
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
</configuration>

异常日志：

    (System.Net.HttpWebResponse)(ex.Response)   {System.Net.HttpWebResponse}    System.Net.HttpWebResponse
    base    {System.Net.HttpWebResponse}    System.Net.WebResponse {System.Net.HttpWebResponse}
        CharacterSet    "ISO-8859-1"    string
        ContentEncoding ""  string
        ContentLength   1047    long
        ContentType "text/html" string
        Cookies {System.Net.CookieCollection}   System.Net.CookieCollection
        Headers {
            Access-Control-Allow-Origin: *
            Content-Length: 1047
            Cache-Control: private
            Content-Type: text/html
            Date: Tue, 18 Sep 2012 22:33:36 GMT
            Set-Cookie: ASP.NET_SessionId=belurseo1i0ureppkspetw1a; path=/; HttpOnly
            Server: Microsoft-IIS/7.0
            X-AspNet-Version: 4.0.30319
            X-Powered-By: ASP.NET
        }   System.Net.WebHeaderCollection
        IsMutuallyAuthenticated false   bool
        LastModified    {9/19/2012 6:34:07 AM}  System.DateTime
        Method  "POST"  string
        ProtocolVersion {1.1}   System.Version
        ResponseUri {http://localhost/service.svc/Update}   System.Uri
        Server  "Microsoft-IIS/7.0" string
        StatusCode  InternalServerError System.Net.HttpStatusCode
        StatusDescription   "The server encountered an error processing the request. Please see the server logs for more details."  string
        SupportsHeaders true    bool

您可能必须在 web.config 中启用大文件支持（httpRuntime、maxRequestLength 参数）。
这是一个示例

<httpRuntime 
 ...
 ...
 maxRequestLength="20485760" 
 ...
 ...
 .../>