android - 向一个 url 发送咨询，但 JSON 返回始终为 null

Question

我有一个问题，我尝试在我的服务器中提取一个 php 的信息，但响应始终为空

我附上接下来使用的代码，我是 Android 新手，但我认为 PC 不会向应用程序发送任何内容

public class MainActivity extends Activity {

//URL to get JSON Array
private static String url = "http://10.69.44.108/odin/mobile/json/";

//JSON Node Names 
private static final String TAG_USER = "user";
private static final String TAG_ID = "id";
private static final String TAG_NAME = "name";
private static final String TAG_EMAIL = "email";

JSONArray user = null;



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);

    // Creating new JSON Parser
    JSONParser jParser = new JSONParser();

    // Getting JSON from URL
    JSONObject json = jParser.getJSONFromUrl(url);

    try {
        // Getting JSON Array
        user = json.getJSONArray(TAG_USER);
        JSONObject c = user.getJSONObject(0);

        // Storing  JSON item in a Variable
        String id = c.getString(TAG_ID);
        String name = c.getString(TAG_NAME);
        String email = c.getString(TAG_EMAIL);

        //Importing TextView
        final TextView uid = (TextView)findViewById(R.id.uid);
        final TextView name1 = (TextView)findViewById(R.id.name);
        final TextView email1 = (TextView)findViewById(R.id.email);

        //Set JSON Data in TextView
        uid.setText(id);
        name1.setText(name);
        email1.setText(email);


} catch (JSONException e) {
    e.printStackTrace();
}



}

Answer 1

在 android 中，不允许在主线程上执行网络操作:

你不能这样做:

// Getting JSON from URL
JSONObject json = jParser.getJSONFromUrl(url);

在onCreate中，您必须将其放入 asyncTask 中.

<小时/>

你可以像这样快速而肮脏地完成它(未经测试!):

//Importing TextView
final TextView uid = (TextView)findViewById(R.id.uid);
final TextView name1 = (TextView)findViewById(R.id.name);
final TextView email1 = (TextView)findViewById(R.id.email);

new AsyncTask<String, JSONObject, JSONObject>(){
    @Override
    protected JSONObject doInBackground(String ... Urls) {
    // Creating new JSON Parser
    JSONParser jParser = new JSONParser();
    // Getting JSON from URL
    JSONObject json = new JSONObject();
    try {
        json = jParser.getJSONFromUrl(Urls[]);
    } catch(JSONException e) {
        // do somthing
        return null
    }
        return json;
    }
    protected void onPostExecute(JSONObject json) {
     try {
        // Getting JSON Array
        user = json.getJSONArray(TAG_USER);
        JSONObject c = user.getJSONObject(0);

        // Storing  JSON item in a Variable
        String id = c.getString(TAG_ID);
        String name = c.getString(TAG_NAME);
        String email = c.getString(TAG_EMAIL);

        //Set JSON Data in TextView
        uid.setText(id);
        name1.setText(name);
        email1.setText(email);

        } catch (JSONException e) {
            e.printStackTrace();
        }
    }
}.execute(url);