公众号服务器url调用返回http 415怎样解决?

java服务端，

代码如下：

@RequestMapping(value = "/validationWeCat",method = RequestMethod.POST, produces = "application/json; charset=utf-8")

@ResponseBody

    public String tempJinyouValidationWeCat(@RequestBody String requestBody){

        System.out.println("requestBody："+requestBody);

        return requestBody;

    }