无法得到回应

Question

         FileInputStream fileInputStream = new FileInputStream(sourceFile);
               URL url = new URL(upLoadServerUri);

               // Open a HTTP  connection to  the URL
               conn = (HttpURLConnection) url.openConnection(); 
               conn.setDoInput(true); // Allow Inputs
               conn.setDoOutput(true); // Allow Outputs
               conn.setUseCaches(false); // Don't use a Cached Copy
               conn.setRequestMethod("POST");
               conn.setRequestProperty("Connection", "Keep-Alive");
               conn.setRequestProperty("ENCTYPE", "multipart/form-data");
               conn.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
               conn.setRequestProperty("uploaded_file", fileName); 

               dos = new DataOutputStream(conn.getOutputStream());

               dos.writeBytes(twoHyphens + boundary + lineEnd); 
               dos.writeBytes("Content-Disposition: form-data; name=\"uploaded_file\";filename=\""
                                         + fileName + "\"" + lineEnd);

               dos.writeBytes(lineEnd);

               // create a buffer of  maximum size
               bytesAvailable = fileInputStream.available(); 

               bufferSize = Math.min(bytesAvailable, maxBufferSize);
               buffer = new byte[bufferSize];

               // read file and write it into form...
               bytesRead = fileInputStream.read(buffer, 0, bufferSize);  

               while (bytesRead > 0) {

                 dos.write(buffer, 0, bufferSize);
                 bytesAvailable = fileInputStream.available();
                 bufferSize = Math.min(bytesAvailable, maxBufferSize);
                 bytesRead = fileInputStream.read(buffer, 0, bufferSize);   

                }

               // send multipart form data necesssary after file data...
               dos.writeBytes(lineEnd);
               dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);

               // Responses from the server (code and message)
               serverResponseCode = conn.getResponseCode();


               **InputStream is = conn.getInputStream();
               BufferedReader rd = new BufferedReader(new InputStreamReader(is));
               String line;
               StringBuffer response = new StringBuffer(); 
               while((line = rd.readLine()) != null) {
                 response.append(line);
                 response.append('\r');
               }
               rd.close();**


            //   String serverResponseMessage = conn.getResponseMessage();

               Log.i("uploadFile", "HTTP Response is : " 
                       + line + ": " + serverResponseCode);

               if(serverResponseCode == 200){

                   runOnUiThread(new Runnable() {
                        public void run() {

                            String msg = "File Upload Completed.\n\n See uploaded file here : \n\n"
                                          +" http://www.androidexample.com/media/uploads/"
                                          +uploadFileName;

                            messageText.setText(msg);
                            Toast.makeText(UploadToServer.this, "File Upload Complete.", 
                                         Toast.LENGTH_SHORT).show();
                        }
                    });                
               }    

               //close the streams //
               fileInputStream.close();
               dos.flush();
               dos.close();

          } catch (MalformedURLException ex) {

              dialog.dismiss();  
              ex.printStackTrace();

              runOnUiThread(new Runnable() {
                  public void run() {
                      messageText.setText("MalformedURLException Exception : check script url.");
                      Toast.makeText(UploadToServer.this, "MalformedURLException", Toast.LENGTH_SHORT).show();
                  }
              });

              Log.e("Upload file to server", "error: " + ex.getMessage(), ex);  
          } catch (Exception e) {

              dialog.dismiss();  
              e.printStackTrace();

              runOnUiThread(new Runnable() {
                  public void run() {
                      messageText.setText("Got Exception : see logcat ");
                      Toast.makeText(UploadToServer.this, "Got Exception : see logcat ", 
                              Toast.LENGTH_SHORT).show();
                  }
              });
              Log.e("Upload file to server Exception", "Exception : " 
                                               + e.getMessage(), e);  
          }
          dialog.dismiss();       
          return serverResponseCode; 

       } // End else block 
     } 

我使用上面的代码将图像上传到服务器上它运行正常。但是我需要在服务器上保存图像后从服务器返回响应。但是我得到空值。我使用php echo语句来写响应。请帮我解决这个问题。谢谢你