使用回調接口實現AsyncTask - 在單個回調接口中處理多個呼叫響應

Question

在我的Android應用程序中，我從一個Activity進行多個API調用。我正在使用以下方法：在Activity中實現接口並從Async類調用該接口函數。

public interface AsyncResponse { 
    public void processFinish(JSONObject sb); 
} 


public class FetchData extends AsyncTask<String, Integer, JSONObject> { 
    HttpURLConnection urlConnection; 
    String url; 
    String method; 
    String payload = null; 
    AsyncResponse delegate = null; 

    public FetchData(AsyncResponse delegate, String url, String method) { 
     this.delegate = delegate; 
     this.url = url; 
     this.method = method; 
    } 

    public FetchData(AsyncResponse delegate, String url, String method, JSONObject payload) { 
     this(delegate, url, method); 
     this.payload = payload.toString(); 
    } 

    @Override 
    protected JSONObject doInBackground(String... args) { 
     BufferedReader reader = null; 

     try { 
      URL url = new URL(this.url); 

      // Open HTTP connection 
      urlConnection = (HttpURLConnection) url.openConnection(); 

      // HTTP method GET/POST/PUT/DELETE 
      urlConnection.setRequestMethod(this.method); 

      // handle issues 
      int statusCode = urlConnection.getResponseCode(); 

      // Get the response 
      InputStream inputStream = urlConnection.getInputStream(); 
      if(inputStream == null) { 
       // Nothing to do 
       return null; 
      } 
      reader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8")); 
      String inputLine = null; 
      StringBuffer response = new StringBuffer(); 

      while ((inputLine = reader.readLine()) != null) { 
       response.append(inputLine + "\n"); 
      } 

      return new JSONObject(response.toString()); 
     } catch(Exception e) { 
      try { 
       // Return error response 
      } catch(Exception e1) { 
       System.out.println(e1); 
       return null; 
      } 
     } finally { 
      if (urlConnection != null) { 
       urlConnection.disconnect(); 
      } 
      if (reader != null) { 
       try { 
        reader.close(); 
       } catch (final IOException e) { 
        Log.e("PlaceholderFragment", "Error closing stream", e); 
       } 
      } 
     } 
    } 

    @Override 
    protected void onPostExecute(JSONObject result) { 
     super.onPostExecute(result); 
     this.delegate.processFinish(result); 
    } 
} 


public class AsyncTasks extends AppCompatActivity implements AsyncResponse { 
    TextView view = null; 
    int a = 1; 
    Utility utility = Utility.getInstance(); 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_async_tasks); 
     new FetchData(this, "<url 1>", "GET").executeOnExecutor(THREAD_POOL_EXECUTOR); 

     new FetchData(this, "<url 2>", "GET").executeOnExecutor(THREAD_POOL_EXECUTOR); 
    } 

    @Override 
    public void processFinish(JSONObject data) { 
     utility.showDialog(this, data.toString()); 
    } 
} 

這裏如何處理processFinish（）接口函數第二GET調用的響應？什麼是最好的方法？

Answer 1

public interface AsyncResponse { 
    //Add requestCode to identify request. 
    public void processFinish(JSONObject sb, int requestCode); 
} 


public class FetchData extends AsyncTask<String, Integer, JSONObject> { 
    HttpURLConnection urlConnection; 
    String url; 
    String method; 
    String payload = null; 
    AsyncResponse delegate = null; 
    int requestCode; 

    public FetchData(String url, String method) { 
     this(url, method, null); 
    } 

    public FetchData(String url, String method, JSONObject payload) { 
     this.url = url; 
     this.method = method; 
     if(payload!=null){ 
      this.payload = payload.toString(); 
     } 
    } 

    //You can set AsyncResponse and RequestCode in constructor also. 
    public FetchData setListener(AsyncResponse asyncResponse, int requestCode){ 
     this.delegate = asyncResponse; 
     this.requestCode = requestCode; 
     return this; 
    } 

    @Override 
    protected JSONObject doInBackground(String... args) { 
     .... 
    } 

    @Override 
    protected void onPostExecute(JSONObject result) { 
     super.onPostExecute(result); 
     if(delegate!=null){   
      //post result with given requestCode 
      this.delegate.processFinish(result, requestCode); 
     } 
    } 
} 


public class AsyncTasks extends AppCompatActivity implements AsyncResponse { 

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

     // Make first call with request code as 1  
     new FetchData("<url 1>", "GET").setListener(this, 1).executeOnExecutor(THREAD_POOL_EXECUTOR); 

     // Make second call with request code as 2 
     new FetchData("<url 2>", "GET").setListener(this, 2).executeOnExecutor(THREAD_POOL_EXECUTOR); 
    } 

    @Override 
    public void processFinish(JSONObject data, int requestCode) { 
     switch(requestCode){ 
      case 1: 
      //perform task on 1st call finish 
      break; 
      case 2: 
      utility.showDialog(this, data.toString()); 
      //perform task on 2nd call finish 
      break; 
     } 
    } 
}