Android巧用Fragment解耦onActivityResult详解

时间：2021-01-21 10:52:23|栏目：Android代码|点击：次

前言

最近在研究jsbridge, 一直在想怎么样才能让需要startActivityForResult比如打开相机拍照这样的操作在webView中能更简单一点, 直到我发现了这篇文章

看了之后, 马上模仿了文中的代码实现了一下.

Fragment:

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);
  }
 }
}

ActResultRequest:

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);
 }
}

MainActivity:

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();
   }
  });
 }
}

SecondActivity

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();
 }
}

按照这样的思路, 如果需要简化jsbridge中startActivityForResult的操作, 我们只需要把Fragment和WebView绑定在一起.比如给这个Fragment取名叫WebViewFragment, 它的布局中只有一个我们封装好的WebView, 这个WebView需要监听jsbridge的所有事件我们都在fragment中写好, 包括onActivityResult中的事件, 当然也可以在这个fragment中用一个专门的管理类来管理注册的事件.以后Activity中有用到WebView的地方我们就直接用这个WebViewFragment就好了.也就是说, 把这个WebViewFragment, 当成我们之前的WebView.

github地址:

EasyOnActivityResult

总结

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本文标题：Android巧用Fragment解耦onActivityResult详解

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