从外部代码抓取当前web api请求

我正在尝试编写代码，它将从web api动作的当前请求中抓取一个文件，然后将该文件保存到服务器。此代码位于与主Web api项目分离的自己的项目中。当代码运行我得到这个错误：从外部代码抓取当前web api请求

Could not load file or assembly 'System.Web.Http, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

这是在自己的项目中的代码应该捕获请求：

public class Upload<T> where T : HttpRequestMessage 
{ 
    private readonly T _req; 
    // Constructor 
    public Upload() 
    { 

    } 

    public Upload(T t) 
    { 
     _req = t; 
    } 

// METHODS 
    public async Task<HttpResponseMessage> SingleFile(string dirName, string typeDir) 
    { 
     // check request 

     if (!_req.Content.IsMimeMultipartContent()) 
     { 
      return _req.CreateResponse(HttpStatusCode.UnsupportedMediaType); 
     } 

     // More code etc. 
    } 
}

这是从主网页API项目中调用代码：

[HttpPost] 
    public HttpResponseMessage CreateProduct() 
    { 
     var up = new FileTools.Upload<HttpRequestMessage>(this.Request); 
     var message = up.SingleFile("test", "mytestDir"); // error appears here 

     return message.Result; 
    }

来源

2014-08-27 user1206480