Android Volley发送空的JSON对象

Question

我想将一些表单详细信息从我的android应用发送到后端php脚本中。我为此使用了Android Volley库。它发送json对象（从android端报告没有错误），但是我的php脚本没有捕获任何json对象。

Android代码

 StringRequest postRequest = new StringRequest(Request.Method.POST, posturl,
                new Response.Listener<String>()
                {
                    @Override
                    public void onResponse(String response) {
                        // response
                        Log.d("Response", response);
                    }
                },
                new Response.ErrorListener()
                {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        // error
                      Log.d("Error.Response", error.toString());
                    }
                }
        ) {
            @Override
            public Map<String, String> getHeaders() throws AuthFailureError {
                Map<String, String> params = new HashMap<String, String>();
                params.put("Content-Type", "application/json");
                return params;
            }
            @Override
            protected Map<String, String> getParams()
            {
                Map<String, String> params = new HashMap<String, String>();


                params.put("name", "John");
                params.put("birthdate", "1988 03 29");


                return params;
            }
        };

        queue.add(postRequest);

PHP代码

  if(strcasecmp($_SERVER['REQUEST_METHOD'], 'POST') != 0){
            throw new Exception('Request method must be POST!');
        }

        $contentType = isset($_SERVER["CONTENT_TYPE"]) ? trim($_SERVER["CONTENT_TYPE"]) : '';
        if(strcasecmp($contentType, 'application/json') != 0){
            throw new Exception('Content type must be: application/json');
        }

        $decoded = trim(file_get_contents("php://input"));


        $decoded1 = json_decode($decoded, true);

        printf("decoded data %s",$decoded1);


        if(!is_array($decoded1)){
            throw new Exception('Received content contained invalid JSON!');
        }