JsonObjectRequest 扩展 JsonRequest 直接覆盖了 getBody() 方法，所以你的 getParam() 永远不会调用，我建议您扩展 StringRequest 而不是 JsonObjectRequest.

The JsonObjectRequest is extended JsonRequest which override getBody() method directly, so your getParam() would never invoke, I recommend you extend StringRequest instead of JsonObjectRequest.

您可以查看这个答案了解更多详情.

your can check this answer for more details.

顺便说一下，您还有另一种选择:基于 Volley 的 Netroid更多功能.

by the way, you've another choice : Netroid, that based Volley, offered more features at all.