Question

我正在使用来自mySQL的数据来填充android studio上的列表视图。我希望根据将数据上传到mysql的用户来过滤此数据，这样用户只能看到该特定用户添加的播放器。

以下php和android studio代码不会向列表视图返回任何内容。

 <?php
include 'conn.php';

$people= array();

$organise= $_GET['user_id'];

$sql= "SELECT name FROM panel WHERE user_id='$organise'";

$stmt= $conn->prepare($sql);

$stmt->execute();

$stmt->bind_result($name);

while ($stmt->fetch()) {
  $temp= [
    'name'=>$name
  ];
  array_push($people,$temp);
}
echo json_encode($people);

 ?>

以下代码包含在Panel.java类中

public class Panel extends AppCompatActivity {
    TextView etPlayerName, etPlayerTel, etPlayerEmail;
    Button btnPlayerAdd;
    ListView lvNames;

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

        etPlayerName = findViewById(R.id.etPlayerName);
        etPlayerTel = findViewById(R.id.etPlayerTel);
        etPlayerEmail = findViewById(R.id.etPlayerEmail);
        btnPlayerAdd = findViewById(R.id.etPlayerAdd);


        lvNames=(ListView) findViewById(R.id.lvNames);

        getJSON("http://channan06.lampt.eeecs.qub.ac.uk/summer/crap.php");
    }

    //this method is actually fetching the json string
    private void getJSON(final String urlWebService) {


        class GetJSON extends AsyncTask<Void, Void, String> {

            @Override
            protected void onPreExecute() {
                super.onPreExecute();
            }


            @Override
            protected void onPostExecute(String s) {
                super.onPostExecute(s);


                try {
                    loadIntoListView(s);
                }catch (JSONException e){
                    e.printStackTrace();
                }
            }


            @Override
            protected String doInBackground(Void... voids) {



                try {
                    //creating a URL
                    URL url = new URL(urlWebService);

                    //Opening the URL using HttpURLConnection
                    HttpURLConnection con = (HttpURLConnection) url.openConnection();

                    //StringBuilder object to read the string from the service
                    StringBuilder sb = new StringBuilder();

                    //We will use a buffered reader to read the string from service
                    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));

                    //A simple string to read values from each line
                    String json;

                    //reading until we don't find null
                    while ((json = bufferedReader.readLine()) != null) {

                        //appending it to string builder
                        sb.append(json + "\n");
                    }

                    //finally returning the read string
                    return sb.toString().trim();
                } catch (Exception e) {
                    return null;
                }

            }
        }

        //creating asynctask object and executing it
        GetJSON getJSON = new GetJSON();
        getJSON.execute();
    }

    private void loadIntoListView(String json) throws JSONException{
        JSONArray jsonArray= new JSONArray(json);
        String [] people= new String[jsonArray.length()];

        for(int i=0;i<jsonArray.length();i++){
            JSONObject obj= jsonArray.getJSONObject(i);
            people[i]=obj.getString("name");
        }
        ArrayAdapter<String> arrayAdapter= new ArrayAdapter<>(this, android.R.layout.simple_list_item_1,people);
        lvNames.setAdapter(arrayAdapter);
    }

    public void onAddPlayer(View v) {
        if (etPlayerName.getText().toString().isEmpty() || etPlayerTel.getText().toString().isEmpty()
                || etPlayerEmail.getText().toString().isEmpty()) {

            Toast.makeText(Panel.this, "Please enter all details", Toast.LENGTH_SHORT).show();
        } else {

            String str_name = etPlayerName.getText().toString();
            String str_phone = etPlayerTel.getText().toString();
            String str_email = etPlayerEmail.getText().toString();


            String type = "addplayer";

            BackgroundWorker backgroundWorker = new BackgroundWorker(this);
            backgroundWorker.execute(type, str_name, str_phone, str_email);

            Toast.makeText(Panel.this, "Player added to database", Toast.LENGTH_SHORT).show();


        }
    }

}

Answer 1

您可以使用准备好的方法，但不能使用参数化的查询方法，这是不好的方法。好，看看下面的代码片段。

//I supposed you are using pdo
$organise= $_GET['user_id'];
$stmt = $conn->prepare("SELECT name FROM panel WHERE user_id=:user_id");
$stmt->execute(['user_id' => $organise]); 
$data = $stmt->fetchAll();
echo json_encode($data);

使用where子句检索MySql数据

1 个答案: