用HttpClent的HttpPost，实现在http head部分加入（AppKey和Secret等）消息头，
并用Entity传post参数值，实现接口传送数据。
是一个很好的httpclient的一种应用
附带appche的httpclient-4.5.3.jar和httpcore-4.4.6.jar依赖包(Using HttpClent's HttpPost, the message header is added to the HTTP head part (AppKey and Secret),
Using Entity to pass post parameter value, the interface can transmit data.
It's an excellent application of httpclient
Httpclient-4.5.3.jar and httpcore-4.4.6.jar dependency packages with appche)