Android 无法通过 API 接收多条记录

Posted 2023-05-07

【中文标题】Android 无法通过 API 接收多条记录

【英文标题】：Android not able to receive multi records via API

【发布时间】：2021-07-12 19:59:48

【问题描述】：

我正在构建一个基本的 android 应用程序来插入和读取应用程序中的记录。我能够从 mysql 数据库中读取单条记录并将其显示在活动页面上，但是当查询返回多条记录时，我无法显示它们。我想以表格形式显示它们

我正在调用 API，下面是我的代码：

$stmt = $conn->prepare("SELECT col1, col2 FROM my_table WHERE col3 = ?"); 
$stmt->bind_param("s",$id);
$stmt->execute();
$stmt->bind_result($col1, $col2);
$stmt->fetch();
                
$user = array(
                'col1'=>$col1, 
                'col2'=>$col2
                );
                            
$stmt->close();
$response['error'] = false; 
$response['message'] = 'Records Pulled Successfully.'
$response['user'] = $user; 

下面是我的 mainactivity.java 代码：

package com.javapaper.test;

public class MainActivity extends AppCompatActivity 

    

    @Override
    protected void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        

        //if the user is not logged in
        //starting the login activity
        if (!SharedPrefManager.getInstance(this).isLoggedIn()) 
            finish();
            startActivity(new Intent(this, LoginActivity.class));
        
       
        User user = SharedPrefManager.getInstance(this).getUser();
        textViewUsername.setText(user.getUsername());
        col3 = user.getId();

        getdatafromdb(col3);  

        //when the user presses logout button
        //calling the logout method
       findViewById(R.id.btn_LogoutPlaceOrd).setOnClickListener(new View.OnClickListener() 
          @Override
         public void onClick(View view) 
            finish();
           SharedPrefManager.getInstance(getApplicationContext()).logout();
        
       );
    

    private void getdatafromdb(int col3) 
        
        //if it passes all the validations

        class getdatafromdb extends AsyncTask<Void, Void, String> 

            private ProgressBar progressBar;

            @Override
            protected String doInBackground(Void... voids) 
                //creating request handler object
                RequestHandler requestHandler = new RequestHandler();

                //creating request parameters
                HashMap<String, String> params = new HashMap<>();
                params.put("col3", col3);
                

                //returing the response
                return requestHandler.sendPostRequest(URLs.URL_PLACEORD, params);
            

            @Override
            protected void onPreExecute() 
                super.onPreExecute();
                //displaying the progress bar 
                progressBar = (ProgressBar) findViewById(R.id.pb_placeord);
                progressBar.setVisibility(View.VISIBLE);
            

            @Override
            protected void onPostExecute(String s) 
                super.onPostExecute(s);
                //hiding the progressbar after completion
                progressBar.setVisibility(View.GONE);

                try 
                    //converting response to json object
                    JSONObject obj = new JSONObject(s);

                    //if no error in response
                    if (!obj.getBoolean("error")) 
                        Toast.makeText(getApplicationContext(), obj.getString("message"), Toast.LENGTH_SHORT).show();

                        //getting the order id from the response

                        JSONObject userJson = obj.getJSONObject("col1");

                        //creating a new user object 
                        User user = new User(
                                userJson.getInt("col1"),
                                userJson.getString("col2"),
                                
                        );


// need help here if above is the right way to receive multiple rows and then how to display them on listview or tableview]]

                                              
                     else 
                        Toast.makeText(getApplicationContext(), "Some error occurred", Toast.LENGTH_SHORT).show();
                    
                 catch (JSONException e) 
                    e.printStackTrace();
                
            
        

        //executing the async task
        Placeorder ru = new Placeorder();
        ru.execute();
    

【参考方案1】：

$stmt = $conn->prepare("SELECT col1,col2 FROM my_table where col3 = ?"); 
                            $stmt->bind_param("s",$var);
                                $stmt->execute();
                                                        
                                $stmt->bind_result($col1, $col2);
                            
                               $stmt->store_result();
                                                         
                      $n = '0';
                        while($obj =$stmt->fetch()) 
                            
                                       
                                $user[$n] = array(
                                'ret_var1'=>$col1, 
                                'ret_var2'=>$col2
                                
                                
                            );

                                                      $n = $n+1;
                                                //while
                                             $stmt->close();
                        
                                       
                  $response['user'] = $user;
                  $response['error'] = false; 
              $response['message'] = 'Data Pulled Successfully. Total Records are-' .$n;