在WCF数据服务上请求application / json时请求的媒体类型不受支持

I am building a WCF data service (with .net 4.5 VS 2012) using Reflection Provider (https://msdn.microsoft.com/en-us/library/dd728281.aspx) on my existing classes. I can successfully access the service with "Accept: application/atom+xml" in request header. however, I got an error "Unsupported media type requested" when changing "Accept" to "application/json" in request header. As I learned, WCF data service supports JSON, what should I do to enable querying json data on the service?I am building a WCF data service (with .net 4.5