我们如何让一个Android片段显示在react-native中？

Question

我已经尝试过构建原生的ui组件,它经常受到欢迎.该组件似乎没有以react-native呈现.

虽然,对于这个问题,我特意尝试在反应原生中呈现Android片段,但没有任何东西出现.示例代码:

public class PreferenceViewManager extends SimpleViewManager<FrameLayout> {
    public static final String REACT_CLASS = "RCTPreferenceView";

    private WeakReference<Activity> activityWeakReference;

    public PreferenceViewManager(WeakReference<Activity> activityWeakReference) {
        this.activityWeakReference = activityWeakReference;
    }

    @Override
    public String getName() {
        return REACT_CLASS;
    }

    @Override
    public FrameLayout createViewInstance(ThemedReactContext context) {
        Log.d(REACT_CLASS, "PreferenceView createViewInstance");
        final FrameLayout view = new FrameLayout(context);
        view.setId(View.generateViewId());
        // Testing if the view does get rendered, it should show white even if fragment is not rendered!
        view.setBackgroundColor(Color.WHITE);
        // not sure where to call fragment beginTransaction properly, the code below is just for testing
        view.postDelayed(new Runnable() {
            @Override
            public void run() {
                onAfterUpdateTransaction(view);
            }
        }, 2000);
        return view;
    }

    @Override
    public void onAfterUpdateTransaction(FrameLayout view) {
        super.onAfterUpdateTransaction(view);

        activityWeakReference.get().getFragmentManager().beginTransaction().replace(view.getId(), new PreferenceView()).commit();
        Log.d(REACT_CLASS, "PreferenceView Commit"); // for debug
    }
}

使用上面的视图管理器,视图所在的位置甚至不是白色,表示FrameLayout本身不会被渲染.

我究竟做错了什么？

Answer 1

实际上，您几乎走对了方向。您的 FrameLayout 未呈现的原因是您没有在 ReactNative 中明确添加样式以指定其高度和宽度。但是，即便如此，您的片段也不会被渲染。您可以执行一些更改来渲染片段。

在您的 ViewManager 中，执行以下几项更改：

@Override
public FrameLayout createViewInstance(ThemedReactContext context) {
    final FrameLayout view = new FrameLayout(context);
    MyFragment fragment = MyFragment.newInstance();
    // Add the fragment into the FrameLayout
    reactContext.getCurrentActivity().getFragmentManager()
            .beginTransaction()
            .add(fragment, "My_TAG")
            .commit();
    // Execute the commit immediately or can use commitNow() instead
    reactContext.getCurrentActivity().getFragmentManager().executePendingTransactions();
    // This step is needed to in order for ReactNative to render your view
    addView(fragment.getView(), LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
    return view;
}

然后在你的 ReactNative 组件中

class ExampleComponent extends React.Component {
  render() {
    return (
      <View>
        <Text>Hello</Text>
        <RCTPreferenceView
          {...this.props}
          style={{ height: "80%", width: "100%" }}
        />
      </View>
    );
  }
}

希望这可以帮助那些试图在 ReactNative 视图中渲染片段的人

Answer 2

您必须在视图管理器中公开 Fragment，然后将视图管理器桥接到 React Native javascript 代码。