Android巧用Fragment解耦onActivityResult详解

public class OnActResultEventDispatcherFragment extends Fragment{
 public static final String TAG = "on_act_result_event_dispatcher";
 public int mRequestCode = 0x11;
 private SparseArray<ActResultRequest.Callback> mCallbacks = new SparseArray<>();

 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setRetainInstance(true);
 }

 public void startForResult(Intent intent, ActResultRequest.Callback callback) {
  // mRequestCode与callback需要一一对应
  mCallbacks.put(mRequestCode, callback);
  startActivityForResult(intent, mRequestCode);
  mRequestCode++;
 }

 @Override
 public void onActivityResult(int requestCode, int resultCode, Intent data) {
  super.onActivityResult(requestCode, resultCode, data);

  ActResultRequest.Callback callback = mCallbacks.get(requestCode);
  mCallbacks.remove(requestCode);

  if (callback != null) {
   callback.onActivityResult(resultCode, data);
  }
 }
}

public class ActResultRequest {
 private OnActResultEventDispatcherFragment fragment;

 public ActResultRequest(FragmentActivity activity) {
  fragment = getEventDispatchFragment(activity);
 }

 private OnActResultEventDispatcherFragment getEventDispatchFragment(FragmentActivity activity) {
  FragmentManager fragmentManager = activity.getSupportFragmentManager();


  OnActResultEventDispatcherFragment fragment = findEventDispatchFragment(fragmentManager);
  if (fragment == null) {
   fragment = new OnActResultEventDispatcherFragment();
   fragmentManager
     .beginTransaction()
     .add(fragment, OnActResultEventDispatcherFragment.TAG)
     .commitAllowingStateLoss();
   fragmentManager.executePendingTransactions();
  }
  return fragment;
 }

 private OnActResultEventDispatcherFragment findEventDispatchFragment(FragmentManager manager) {
  return (OnActResultEventDispatcherFragment) manager.findFragmentByTag(OnActResultEventDispatcherFragment.TAG);
 }

 public void startForResult(Intent intent, Callback callback) {
  fragment.startForResult(intent, callback);
 }

 public interface Callback {

  void onActivityResult(int resultCode, Intent data);
 }
}

public class MainActivity extends AppCompatActivity {
 private static final String TAG = "MainActivity";
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
 }
 
 public void start(View view) {
  Intent intent = new Intent(this, SecondActivity.class);
  ActResultRequest request = new ActResultRequest(this);
  request.startForResult(intent, new ActResultRequest.Callback() {
   @Override
   public void onActivityResult(int resultCode, Intent data) {
    Log.d(TAG, "resultCode = " + resultCode);
    String name = data.getStringExtra("name");
    Log.d(TAG, "name = " + name);
    Toast.makeText(MainActivity.this, "name = " + name + ", resultCode = " + resultCode,
      Toast.LENGTH_SHORT).show();
   }
  });
 }
}

public class SecondActivity extends AppCompatActivity {
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_second);

 }

 public void returnResult(View view) {
  Intent intent = new Intent();
  intent.putExtra("name", "mundane");
  setResult(RESULT_OK, intent);
  finish();
 }
}