当它在另一个类中时如何从 AsyncTask 获取值

Question

我需要从我的 AsyncTask 中获取结果。我实际上可以从任务中得到结果，但我只是不知道如何从需要它的方法中得到它。正如将要看到的，AsyncTask 属于不同的类。如果您有任何问题，我可以澄清一下，请告诉我，以便我可以编辑帖子。请参阅下面的代码：

public class UserRepository {
    private UserDao userDao;
    private User user;
    private LiveData<List<User>> allUsers;

    public UserRepository(Application application) {
        AtsDatabase database = AtsDatabase.getInstance(application);
        userDao = database.userDao();
        allUsers = userDao.getUsers();
    }

 private MutableLiveData<User> userSearched = new MutableLiveData<>();
 private void asyncFinished(User userResult) {
    if(userResult == null) return;
    Log.i("TAG", "asyncFinished: " + userResult.getLastName());
    userSearched.setValue(userResult);
 }

    public LiveData<User> getUserByUserName(String userName) {
        new GetUserByUserNameAsyncTask(userDao).execute(userName); ===> I NEED THE RESULT HERE SO I CAN PASS IT TO MY VIEW MODEL
    }

    public LiveData<List<User>> getAllUsers() { return allUsers; }

    private static class InsertUserAsyncTask extends AsyncTask<User, Void, Void> {
        private UserDao userDao;

        private InsertUserAsyncTask(UserDao userDao) { this.userDao = userDao; }

        @Override
        protected Void doInBackground(User... users) {
            userDao.insert(users[0]);
            return null;
        }
    }

    private static class GetUserByUserNameAsyncTask extends AsyncTask<String, Void, User> {
        private LiveData<User> user;
        private UserDao userDao;

        private GetUserByUserNameAsyncTask(UserDao userDao) { this.userDao = userDao; }

        @Override
        protected User doInBackground(String... strings) {
             user = userDao.getUserByUserName(strings[0]); ======> I GET RESULT HERE 
             return null;
        }

         @Override
        protected void onPostExecute(User user) {
        super.onPostExecute(user);
        Log.i("TAG", "onPostExecute: "+user.getLastName());
        delegate.asyncFinished(user);
    }
    }
}

我该如何做到这一点？谢谢。

Answer 1

首先，AsyncTask 现在已弃用。

如果您仍想使用它，请创建一个MutableLiveData 并 在暴露的函数中将其作为LiveData 返回，然后通过AsyncTask 的构造函数将其传递。 得到结果后使用MutableLiveData的postValue方法设置结果。