Android：使用异步任务的同步方式：Json 上传问题

Question

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我正在尝试以 json 格式发送多个学生数据及其响应。

问题

当表格中有多行时。该函数一次发出多个请求。然后我从回调函数得到多个响应......我想要一个请求及其回调。然后提出新的请求

我想要这个

 final ConnectToServer connect = new ConnectToServer();
            connect.extConnectToServer(AdminSection.this,new ConnectToServer.Callback() 

每个请求发出后调用的函数。完成整个循环后调用回调函数。

代码

 public void Uploadalldata()
        {    
            if(isOnline())
            {   
              JSONObject StudentData = new JSONObject();    
               try
                 {

             String android_id = Secure.getString(this.getContentResolver(),Secure.ANDROID_ID);
             DBHelper db = new DBHelper(getApplicationContext());
             List<StudentClass> StudentDataAll = db.getAllStudentData();
             for(int iCount=0; iCount< StudentDataAll.size(); iCount++)
                {
                 StudentClass objStudentClass= (StudentClass)StudentDataAll.get(iCount);
                 String sSingleStudentCompleteDetails= android_id +","+ objStudentClass.RegistrationId + "," + objStudentClass.Name + "," + objStudentClass.SchoolID + "," + objStudentClass.Class + "," + objStudentClass.RollNo + "," + objStudentClass.RegistrationDate;
                 String sSingleStudentCompleteResponse = "";     
                 String strStudentID = objStudentClass.RegistrationId;       
                 StudentIDForSave = strStudentID;

                 List<StudentResponse> StudentResponse = db.getStudentResponseOnStudentID(strStudentID);

                    for(int iOptionCount=0; iOptionCount<StudentResponse.size(); iOptionCount++)
                        {

                           StudentResponse objStudentResponse=StudentResponse.get(iOptionCount);
                           if(iOptionCount>0) 
                        sSingleStudentCompleteResponse += ",";

                        sSingleStudentCompleteResponse += objStudentResponse.QuestionID + "-" + objStudentResponse.OptionID;

                        }
                    StudentData.put("StudentDetails", sSingleStudentCompleteDetails);
                    StudentData.put("Responses", sSingleStudentCompleteResponse);

                    JSONObject finaldata = new JSONObject();
                    finaldata.put("RegisterStudentRequest", StudentData);

         final ConnectToServer connect = new ConnectToServer();
            connect.extConnectToServer(AdminSection.this,new ConnectToServer.Callback() 
            {
                public void callFinished(String result)
                {
                    JSONObject resp = null;

                    try 
                    {
                        resp = new JSONObject(result);
                        JSONObject UploadStudentDataResult = resp.getJSONObject("RegisterStudentResult");

                        String strMessage = UploadStudentDataResult.getString("IsUploaded");

                        if (StudentIDForSave != null)
                        {
                            SQLiteDatabase db;
                            ContentValues values = new ContentValues();
                            values.put(DBHelper.isUploaded, strMessage);


                        // Call update method of SQLiteDatabase Class and close after
                        // performing task
                        db = helper.getWritableDatabase();
                        db.update(DBHelper.TABLEStudent, values, DBHelper.S_ID + "=?",
                                new String[] { StudentIDForSave});
                        db.close();
                        //Toast.makeText(getBaseContext(), "saved", Toast.LENGTH_LONG).show();
                        }
//                      else
//                      {
//                          Toast.makeText(getBaseContext(), "Data not saved", Toast.LENGTH_LONG).show();
//                      }

                    }


                    catch (final JSONException e)
                    {

                    }

                }
                    }, "http://myurl/Service/RegisterStudent", finaldata, "POST");
                connect.execute(finaldata).get();


     }

 }
  catch (Exception e) {
     Log.d("InputStream", e.getLocalizedMessage());
}
            }
     }

Answer 1

As per the docs here，可以通过“get()”方法同步使用AsyncTask类。

一个简单的例子：

MyAsyncTask task = new MyAsyncTaskTask();
String result = task.execute().get();

class MyAsyncTask extends AsyncTask<Void,Void,String>{...}

根据其中一个 cmets，Volley 还具有异步运行的能力。

Answer 2

合适的解决方案。

protected void sendJson()
      {
          if(isOnline())
            {   
            Thread t = new Thread() {

                public void run() {
                    Looper.prepare(); //For Preparing Message Pool for the child Thread
                    HttpClient client = new DefaultHttpClient();
                    HttpConnectionParams.setConnectionTimeout(client.getParams(), 100000); //Timeout Limit
                    HttpResponse response;
                 //   JSONObject json = new JSONObject();

                    try {
                    String URL  ="http://{Your URL }/Service/RegisterStudent";
                        HttpPost post = new HttpPost(URL);

                        JSONObject StudentData = new JSONObject();  

                     String android_id = Secure.getString(AdminSection.this.getContentResolver(),Secure.ANDROID_ID);
                     DBHelper db = new DBHelper(getApplicationContext());
                     List<StudentClass> StudentDataAll = db.getAllStudentData();
                     for(int iCount=0; iCount< StudentDataAll.size(); iCount++)
                        {
                         StudentClass objStudentClass= (StudentClass)StudentDataAll.get(iCount);
                         String sSingleStudentCompleteDetails= android_id +","+ objStudentClass.RegistrationId + "," + objStudentClass.Name + "," + objStudentClass.SchoolID + "," + objStudentClass.Class + "," + objStudentClass.RollNo + "," + objStudentClass.RegistrationDate;
                         String sSingleStudentCompleteResponse = "";     
                         String strStudentID = objStudentClass.RegistrationId;       
                         StudentIDForSave = strStudentID;

                         List<StudentResponse> StudentResponse = db.getStudentResponseOnStudentID(strStudentID);

                            for(int iOptionCount=0; iOptionCount<StudentResponse.size(); iOptionCount++)
                                {

                                   StudentResponse objStudentResponse=StudentResponse.get(iOptionCount);
                                   if(iOptionCount>0) 
                                sSingleStudentCompleteResponse += ",";

                                sSingleStudentCompleteResponse += objStudentResponse.QuestionID + "-" + objStudentResponse.OptionID;

                                }
                            StudentData.put("StudentDetails", sSingleStudentCompleteDetails);
                            StudentData.put("Responses", sSingleStudentCompleteResponse);

                            JSONObject finaldata = new JSONObject();
                            finaldata.put("RegisterStudentRequest", StudentData);

                        // Toast.makeText(getBaseContext(), finaldata.toString(), Toast.LENGTH_LONG).show();



                        StringEntity se = new StringEntity( finaldata.toString());  
                        se.setContentType(new BasicHeader(HTTP.CONTENT_TYPE, "application/json"));
                        post.setEntity(se);
                        response = client.execute(post);

                        String jsonString = EntityUtils.toString(response.getEntity());


                        JSONObject resp = null;  

                        resp = new JSONObject(jsonString);
                        JSONObject UploadStudentDataResult = resp.getJSONObject("RegisterStudentResult");

                        String strMessage = UploadStudentDataResult.getString("IsUploaded");
                          //  Toast.makeText(getBaseContext(), strMessage, Toast.LENGTH_LONG).show();

                            if (StudentIDForSave != null)
                            {
                                SQLiteDatabase db1;
                                ContentValues values = new ContentValues();
                                values.put(DBHelper.isUploaded, strMessage);


                            // Call update method of SQLiteDatabase Class and close after
                            // performing task
                            db1 = helper.getWritableDatabase();
                            db1.update(DBHelper.TABLEStudent, values, DBHelper.S_ID + "=?",
                                    new String[] { StudentIDForSave});
                            db1.close();

                            //Toast.makeText(getBaseContext(), "saved", Toast.LENGTH_LONG).show();
                            }


                    }
                    }catch(Exception e) {
                        e.printStackTrace();
                        //createDialog("Error", "Cannot Estabilish Connection");
                    }

                    Looper.loop(); //Loop in the message queue
                }
            };

            t.start();   
            }

        }