好吧，我有一个带有两个后台任务 (Async-Task) 的 Activity 类，这两个任务已在两个单独的类中定义，例如

public class GettingBeaconsList extends AsyncTask<String, String, String> 
public class GettingAirports extends AsyncTask<String, String, String> 

在MainClass中初始化和执行

public class MainClass extends Activity implements DelegateTaskCompleted
{

     int ServiceBoolean = 0;
     public OnClickListener LoadingBeaconList = new OnClickListener()
     {
         public void onClick(View v)
         {
             ServiceBoolean  =1;
             new GettingBeaconsList (context,MainClass.this).execute();
         }
     }

    public OnClickListener LoadingAirportList= new OnClickListener()
    {
         public void onClick(View v)
         {
             ServiceBoolean  =2;
             new GettingAirports(context,MainClass.this).execute();
         }
    }


    @Override
    public void JsonArrayLoaded(JSONArray result) 
    {
        // bla bla or whatever here i write, does not matter
         if(ServiceBoolean  == 1)   { 
                //  Load activity 5
         }

         else if( ServiceBoolean  == 2)
         { 
             //  Load activity 6

         }

        else if( ServiceBoolean==3 )
        {
            // display Toast or Alert Box or load Activity number 8
        } 


    }

}

现在在上面的代码中，MainClass.this 像这样存储为 AsynTask 子类中的接口(interface)引用

private Context context             =   null;
private DelegateTaskCompleted delegate      =   null;

public GettingBeaconsList (Context context,DelegateTaskCompleted delegate)  
{   
    this.context        =   context;
    this.delegate       =   delegate;
}

// And constructor of second AsynTask is same as of First AsynTask Class

private Context context             =   null;
private DelegateTaskCompleted delegate      =   null;

public GettingAirports (Context context,DelegateTaskCompleted delegate) 
{   
    this.context        =   context;
    this.delegate       =   delegate;
}

每个 AsynTask 类或子类的 onPostExecute，JSONArray 被返回或传递回调用类，如下所示。在这种情况下，调用类是 MainClass 但还有其他 Activity 类使用相同的 AsynTask 类(GettingBeaconsList 和 GettingAirports)

protected void onPostExecute(String file_url)   
{           
    pDialog.dismiss();      
    delegate.JsonArrayLoaded(gotNearestbeacons);
}

现在我在 MainClass 中有一个方法 (JsonArrayLoaded) 来处理来自两个不同后台任务或服务的两个响应。我正在使用条件来确定执行了哪个服务/类或 AsynTask。

但我要求最好的方法来解决这种情况，就好像我们将来有 5 个或更多后台服务，它们也只返回一个 JSON 数组，所以我需要为每个服务制作单独的接口(interface)吗？

对于这种情况，面向对象的出路应该是什么？

最佳答案

这是回调的接口(interface)

public interface CallbackReceiver {
    public void receiveData(Object result);

}

使用Asynctask类作为抽象类

public abstract class JsonDataCallback extends AsyncTask<String, String, String> implements CallbackReceiver {
private ProgressDialog mProgressDialog;
Handler handler;
Runnable callback;
Activity activity;


public JsonDataCallback(Activity activity) 
{
     this.activity=activity;
     mProgressDialog = new ProgressDialog(activity);
     mProgressDialog.setMessage("Loading Please Wait.");
     mProgressDialog.setIndeterminate(false);
     mProgressDialog.setMax(100);
     mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
     mProgressDialog.setCancelable(true);
}

public abstract void receiveData(Object object);
@Override
protected void onPreExecute() {
    mProgressDialog =ProgressDialog.show(activity, "", "Please Wait",true,false);
    super.onPreExecute();
}

@Override
protected String doInBackground(String... aurl) {
    String results="";
    // do stuff
    return results;
}


@Override
protected void onPostExecute(String jsonData) {
     if (mProgressDialog != null || mProgressDialog.isShowing()){
         mProgressDialog.dismiss();
 }
     if(jsonData!=null)
     {
         receiveData(jsonData);
     }
}
}

然后在你的代码中这样使用它

String url = ipaddress + "/GrantAdvanceList;
            JsonDataCallback callbackservice = new JsonDataCallback(yourActivity.this) {
                @Override
                public void receiveData(Object object) {
                    jsonRecordsData = (String)object;
                    //do stuff with call back data
                }
            };

        callbackservice.execute(url, null, null);

您可以通过这种方式重用代码。

关于java - 一个界面如何用于不同的后台android任务？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/14253421/