Request Headers:
User-Agent: Fiddler
Host: localhost:3248
Content-Type:
application/json; charset=utf-8
Content-Length: 63
要加上Content-Type: application/json; charset=utf-8，要不是JSON没效
Request Body
{"UserID":4,"UserName":"Parry","UserEmail":"Parry@cnblogs.com"}
紧记，不要写成这样：[{"UserID":4,"UserName":"Parry","UserEmail":"Parry@cnblogs.com"}]
Fiddler进行模拟Post提交json数据，总为null解决方式
原文：http://www.cnblogs.com/jys509/p/3550598.html