AsyncTask 通知父 Activity 完成的最佳方式是什么？

Question

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

    public ListingFoundBeaconService(Context contextGiven, 
                                     JSONObject jsonParams) {
        this.contextGiven = contextGiven;
        this.jsonParams = jsonParams;
    }

    protected void onPreExecute() {
        super.onPreExecute();
        pDialog = new ProgressDialog(contextGiven);
        pDialog.setMessage("Loading list of active Beacons..");
        pDialog.setIndeterminate(false);
        pDialog.setCancelable(true);
        pDialog.show();
        Log.d("onPreExecute","onPreExecute worked" );
    }

    protected String doInBackground(String... args) {}

    protected void onPostExecute(String file_url) {   
        // Two activities will need this thread so I have 
        // kept this as a separate class. Here I want to send a
        // boolean value to the parent activity to show that 
        // the task has completed or not.
    }

我可以在onPostExecute() 函数中触发通知或完成事件侦听器，以便通知启动此类（ListingFoundBeaconService）的父类吗？标准的做法是什么？

Answer 1

最好的方法是调用委托。在你的 AsyncTask 类中创建一个构造函数并有一个委托

委托接口：

public interface TaskDelegate {
    public void taskCompletionResult(String result);
}

现在在AsyncTask:

private TaskDelegate delegate;

public ListingFoundBeaconService(Context contextGiven, 
                                 JSONObject jsonParams,
                                 TaskDelegate delegate) {
    this.contextGiven = contextGiven;
    this.jsonParams = jsonParams;
    this.delegate = delegate;
}

在postExecute:

delegate.taskCompletionResult(result/msg/json);

在您的主类中实现TaskDelegate 并实现一个在任务完成时调用的方法。

Answer 2

将 ListingFoundBeaconService 类抽象化，然后在调用类中重写 onPostExecute。