浅谈Android AsyncTask内存安全的一种使用方式

public class WeakTask<T> extends AsyncTask<Void, Void, T> {

  private WeakReference<OnWeakTaskListener<T>> listenerReference;

  public WeakTask(OnWeakTaskListener<T> listener){
    this.listenerReference = new WeakReference<>(listener);
  }
  @Override
  protected T doInBackground(Void... voids) {
    if (listenerReference.get() != null) {
      return listenerReference.get().middle();
    }else{
      return null;
    }
  }

  @Override
  protected void onPreExecute() {
    super.onPreExecute();
    if (listenerReference.get() != null) {
      listenerReference.get().before();
    }
  }

  @Override
  protected void onPostExecute(T t) {
    super.onPostExecute(t);
    if (listenerReference.get() != null && t != null){
      listenerReference.get().after(t);
    }
  }
}

public interface OnWeakTaskListener<T> {

  void before();

  T middle();

  void after(T t);
}

public class LoginActivity extends AppCompatActivity implements View.OnClickListener {

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

  private void initLayout(){
    findViewById(R.id.btn_login).setOnClickListener(this);
  }

  @Override
  public void onClick(View view) {
    if (view.getId() == R.id.btn_login){
      new WeakTask<Integer>(new LoginWeakTaskListener()).execute();
    } 
  }


  private class LoginWeakTaskListener implements OnWeakTaskListener<Integer>{

    @Override
    public void before() {
       ...开始前
    }

    @Override
    public Integer middle() {
       ...内部执行
    }

    @Override
    public void after(Integer integer) {
       ...结果返回后处理
    }
  }
}