这几天在做Web API 的练习，做到Post数据的时候发现一个问题。HttpResponseMessage不再有泛型的重载。
官方的示例如下：
From the release notes:
Removed HttpRequestMessage<T> and HttpResponseMessage<T>:
Previously there were two ways to specify a request or response with an ObjectContent instance: you could provide an ObjectContentinstance directly, or you could use HttpRequestMessage<T> or HttpResponseMessage<T>. Having two ways of doing the same thing complicated request and response handling, so HttpRequestMessage<T> and HttpResponseMessage<T> have been removed. To create content negotiated responses that contain an ObjectContent use the CreateResponse<T> extension methods on the request message. To send a request that contains an ObjectContent use the PostAsync<T> extension methods on HttpClient. Or, use thePostAsJsonAsync<T> and PostAsXmlAsync<T> extension methods to specify a request that will be specifically formatted with as JSON or XML respectively.
只是简单的添加，没有做异常判断。相比Beta版本，简化了一些。
如果需要添加Location信息，直接加上即可。
参考网站：http://forums.asp.net/t/1813881.aspx/1?What+to+use+instead+of+HttpResponseMessage+T+