android - 如何从 MySQL 数据库中获取数据并将其加载到 Spinner？

Question

我有我的学校项目，我需要从 MySQL 数据库中获取值并将其显示给 Android 中的 Spinner。我正在使用 Android Studio 和 Volley 库进行网络操作，但对如何实现这件事感到困惑。我会感谢你的帮助。谢谢:)

Answer 1

你必须首先创建一个 php 脚本，它将以 json 格式打印你的 mysql 数据库的数据。这里我给你看一个例子让你看看这是我的数据库

现在假设我需要将此表的所有用户名加载到 android 的微调器中。所以这是将给我 json 格式数据的 php 脚本

<?php 

$sql = "SELECT * FROM students";

require_once('dbConnect.php');

$r = mysqli_query($con,$sql);

$result = array();

while($row = mysqli_fetch_array($r)){
    array_push($result,array(
        'username'=>$row['username'],
        'name'=>$row['name'],
        'course'=>$row['course'],
        'session'=>$row['session']
    ));
}

echo json_encode(array('result'=>$result));

mysqli_close($con);

上面的php代码会给出下面的json

{"result":[{"username":"faiz","name":"Faiz Khan","course":"BCA","session":"2014-2017"},{"username":"belal","name":"Belal Khan","course":"MCA","session":"2015-2018"},{"username":"ramiz","name":"Ramiz Khan","course":"MBA","session":"2015-2017"},{"username":"zafar","name":"Zafar Khan","course":"MBA","session":"2014-2016"}]}

现在android代码将是MainActivity.java

public class MainActivity extends AppCompatActivity{
private Spinner spinner;
private ArrayList<String> students;
private JSONArray result;
private TextView textViewName;
private TextView textViewCourse;
private TextView textViewSession;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    students = new ArrayList<String>();
    spinner = (Spinner) findViewById(R.id.spinner);
    spinner.setOnItemSelectedListener(this);
    textViewName = (TextView) findViewById(R.id.textViewName);
    textViewCourse = (TextView) findViewById(R.id.textViewCourse);
    textViewSession = (TextView) findViewById(R.id.textViewSession);
    getData();
}

private void getData(){
    StringRequest stringRequest = new StringRequest("your php script address",
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    JSONObject j = null;
                    try {
                        j = new JSONObject(response);
                        result = j.getJSONArray(Config.JSON_ARRAY);
                        getStudents(result);
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {

                }
            });
    RequestQueue requestQueue = Volley.newRequestQueue(this);
    requestQueue.add(stringRequest);
}

private void getStudents(JSONArray j){
    for(int i=0;i<j.length();i++){
        try {
            JSONObject json = j.getJSONObject(i);
            students.add(json.getString(Config.TAG_USERNAME));
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }
    spinner.setAdapter(new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_spinner_dropdown_item, students));
}
}

来源Android Spinner Example with MySQL Database