Question

我的应用依赖于Service，它在后台与外部硬件保持同步。由于该服务在 main 线程上运行，因此它使用IntentService异步执行任何繁重的工作。以下是解释控制流的代码的最小化示例：

public class MyService extends Service {
  private final Handler handler = new Handler();

  void someMethodDoesCallBarAsynchronously(){
    Intent i = new Intent(this, MyIntentService.class);
    i.putAction(ACTION_FOO);
    i.putExtra(EXTRA_RECEIVER, new MyResultReceiver(handler));
    startService(toGetScannerStatus);
  }

  void receivedFooResult(String bar){
    //...
  }

  public class MyResultReceiver extends ResultReceiver{

    public MyResultReceiver(Handler handler){
      super(handler);
    }

    @Override
    protected void onReceiveResult(int resultCode, Bundle resultData) {
      super.onReceiveResult(resultCode, resultData);

      switch(resultCode){
        case RESULT_CODE_FOO:
          receivedFooResult(resultData.getString(FOO_RESULT));
        break;
      }
    }
  }
}

public class MyIntentService extends IntentService {

  public MyIntentService(){super("MyIntentService");}

  @Override
  protected void onHandleIntent(Intent intent) {
    switch (intent.getAction()) {
      case ACTION_FOO:
        ResultReceiver receiver = intent.getParcelableExtra(EXTRA_RECEIVER);
        Bundle bundle = new Bundle()
        bundle.putString(FOO_RESULT, foo());
        receiver.send(RESULT_CODE_FOO, b);
      break;
  }
}

现在，经过半年和一些更新，Android Studio抱怨MyResultReceiver 实现Parcelable但不提供CREATOR字段。问题一，MyResultReceiver是一个内部类，所以我必须把它放到一个自己的类中。我无法使它static，因为它必须包含对MyService的引用。这仍然很容易：

public class MyService extends Service {
  private final Handler handler = new Handler();

  void someMethodDoesCallBarAsynchronously(){
    Intent i = new Intent(this, MyIntentService.class);
    i.putAction(ACTION_FOO);
    i.putExtra(EXTRA_RECEIVER, new MyResultReceiver(this, handler));
    startService(toGetScannerStatus);
  }

  void receivedFooResult(String bar){
    //...
  }
}

public class MyResultReceiver extends ResultReceiver{
  private final MyService myService;

  public MyResultReceiver(MyService s, Handler handler){
    super(handler);
    this.myService = myService;
  }

  @Override
  protected void onReceiveResult(int resultCode, Bundle resultData) {
    super.onReceiveResult(resultCode, resultData);

    switch(resultCode){
      case RESULT_CODE_FOO:
        myService.receivedFooResult(resultData.getString(FOO_RESULT));
      break;
    }
  }
}

现在我可以添加一个公共静态字段。但如何正确实施CREATOR？

public class MyResultReceiver extends ResultReceiver {

  public static final Parcelable.Creator<MyResultReceiver> CREATOR
    = new Parcelable.Creator<MyResultReceiver>() {
        public MyResultReceiver[] newArray(int size) {
          return new MyResultReceiver[size];
        }
        public MyResultReceiver createFromParcel(Parcel in) {
          // ???
        }
      };

如果你想：为什么这有必要？它将用于什么？

Answer 1

您当前的架构太复杂了：您可以轻松地在一个return zipValues.get(zipCode);中执行此操作但在您遇到问题时由您自己决定：您不需要创建任何Service你得到的是一个lint警告，只需添加像这样的SuppressLint注释：

CREATOR

Android Service扩展了ResultReceiver for IntentService，如何实现CREATOR？

1 个答案: