在Android Studio中使用Java从url获取JSON？

Question

我需要为Android Studio（java）中的一个学校项目解析一个json的URL。我在网上找到了一些对其他人有用的代码，但对我不起作用。以下是我使用的代码（url包含json）

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

        RequestQueue requestQueue = Volley.newRequestQueue(this);
        JsonArrayRequest jsonArrayRequest = new JsonArrayRequest("http://ineke.broeders.be/2021Android/webservice.aspx?do=getSteden", new Response.Listener<JSONArray>() {
            @SuppressLint("SetTextI18n")
            @Override
            public void onResponse(JSONArray response) {
                TextView textView = findViewById(R.id.result);
                for (int i = 0; i< response.length();i++){
                    try {
                        JSONObject jsonObject = response.getJSONObject(i);
                        int ID = jsonObject.getInt("stadID");
                        String stadNaam = jsonObject.getString("stadNaam");
                        String postcode = jsonObject.getString("postcode");
                        textView.setText(textView.getText() + "Name: " + stadNaam + " postcode: " + postcode);
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {

            }
        });
        requestQueue.add(jsonArrayRequest);
    }
}

你有什么办法让它发挥作用吗

Answer 1

你不必使用截击 下面是一个更简单的代码

public class GetData extends AsyncTask<String, String, String>{

      @Override
      protected String doInBackground(String... strings) {
       String current = "";
     try{
    URL url;
    HttpURLConnection urlConnection = null;
    try{
        url = new URL("http://ineke.broeders.be/2021Android/webservice.aspx?do=getSteden");
        urlConnection = (HttpURLConnection) url.openConnection();

        InputStream in = urlConnection.getInputStream();
        InputStreamReader isr = new InputStreamReader(in);

        int data = isr.read();
        while(data !=-1){
            current += (char) data;
            data = isr.read();
        }
        return current;

    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    finally {
        if(urlConnection !=null){
            urlConnection.disconnect();;
        }
    }
     }catch (Exception e){
    e.printStackTrace();
    }
      return current;


    @Override
    protected void onPostExecute(String s) {
   try{
    
    JSONArray jsonArray = new JSONArray(s);
    
        JSONObject jsonObject= jsonArray.getJSONObject(jsonArray);
                   int ID = jsonObject.getInt("stadID");
                    String stadNaam = jsonObject.getString("stadNaam");
                    String postcode = jsonObject.getString("postcode");
                    textView.setText(textView.getText() + "Name: " + stadNaam + " postcode: " + postcode);
            
        

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

} }

使用 新建GetData（）。执行（）

它应该有用，因为它对我有用🙃