java - 从 android 到 PHP 的 HTTP post 调用？

Question

我是 Android Studio 的新手。在下面的代码中，我尝试将数据从 java 发送到后端服务器(在 PHP 中)。正在进行调用，但从服务器端返回 NULL，这是不应该发生的。所以我认为从 java 端发送的输入在 PHP 端没有被正确解释。你能告诉我代码有什么问题吗(PHP 代码完全正确，它不应该返回 NULL)。

          HttpURLConnection httpURLConnection = null;
          JSONObject  Student_det = stu_det.getJSONObject(i);
          String stu_GUID = Student_det.getString("StuGUID");
          String visit_GUID = Student_det.getString("VisitGUID");

            String value = "Rec="+(tableRow+1)+"&SchGUID="+schoolGUID.trim()+"&StuGUID="+stu_GUID.trim()+"&VisitGUID="+visit_GUID.trim()+"&role="+role;
            URL url = new URL("http://52.66.25.82/api/download_student.php");
            String enc_val = URLEncoder.encode(value,"UTF-8");

            httpURLConnection = (HttpURLConnection) url.openConnection();
            httpURLConnection.setDoOutput(true);
            httpURLConnection.setDoInput(true);

            httpURLConnection.setRequestMethod("POST");



            OutputStreamWriter wr = new OutputStreamWriter(httpURLConnection.getOutputStream());
            wr.write( enc_val );
            wr.flush();

            InputStream responseStream = new BufferedInputStream(httpURLConnection.getInputStream());

            BufferedReader responseStreamReader =
                    new BufferedReader(new InputStreamReader(responseStream));


            // Read Server Response
         String output = responseStreamReader.readLine();

Answer 1

正如你所说，对于 Android 新手，从最好的方式开始

尝试使用volley库来实现或者RetroFit 库，简单又简单

volley example

或者

RetroFit example