React Native Android实现键盘focus的na

Android原生可以通过设置android:nextFocusForward等指定导航顺序。RN没有内置支持，可以通过发送event的方式进行指定。

<View  ref={(ref: any) => (this.rootView = ref)}>
...
</View>

然后在componentDidMount的时候发送event给native。

    componentDidMount() {
        if (context.isAndroid() && this.rootView !== 'undefined') {
            var focusOrderList = [];
            ... // Generate focus order list here
            var UIManager = require('UIManager');
            var rootViewHandle = findNodeHandle(this.rootView);
            UIManager.dispatchViewManagerCommand(
                rootViewHandle,
                ViewCommands.NEXT_FOCUS_COMMAND,
                focusOrderList,
            );
        }
    }

自己实现一个ViewManager，继承自ReactViewManager，把默认的ReactViewManager替换掉，然后实现receiveCommand方法。

    @Override
    public void receiveCommand(final ReactViewGroup root, int commandId, @Nullable ReadableArray args) {
        super.receiveCommand(root, commandId, args);

         if (commandId == CMD_NEXT_FOCUS) {
            if (args != null) {
                int length = args.size();
                for (int i = 0; i < length - 1;i++) {
                    View firstView = root.getRootView().findViewWithTag(args.getString(i));
                    View nextFocusView = root.getRootView().findViewWithTag(args.getString(i+1));
                    if (firstView != null && nextFocusView != null) {
                        firstView.setNextFocusForwardId(nextFocusView.getId());
                    }
                }
            }
        }
    }