C#使用post方式提交json数据

尝试了一天,尝试了各种方法,一下方法最直接方便. 

//地址
            string _url = "https://www.dxxxayup.ink/api/user/login";
            //json参数
            string jsonparam = "{ phonenumber:\"18665885202\",pwd:\"tsp\"}";
            var request = (httpwebrequest)webrequest.create(_url);
            request.method = "post";
            request.contenttype = "application/json;charset=utf-8";
            byte[] bytedata = encoding.utf8.getbytes(jsonparam);
            int length = bytedata.length;
            request.contentlength = length;
            stream writer = request.getrequeststream();
            writer.write(bytedata, 0, length);
            writer.close();
            var response = (httpwebresponse)request.getresponse();
            var responsestring = new streamreader(response.getresponsestream(), encoding.getencoding("utf-8")).readtoend();
            messagebox.show(responsestring.tostring());