onShowCustomView（）在android html5视频全屏幕中抛出异常

Question

private class EPUB3WebChromeClient extends WebChromeClient {
    @Override
    public void onShowCustomView(View view, CustomViewCallback callback) {
        if (mCustomView != null) {
            callback.onCustomViewHidden();
            return;
        }
        mCustomViewCallback = callback;
        if(mTargetView !=null)
            mTargetView.addView(view);
        mCustomView = view;
        mContentView.setVisibility(View.GONE);
        mTargetView.setVisibility(View.VISIBLE);
        mTargetView.bringToFront();
    }

    @Override
    public void onHideCustomView() {
        if (mCustomView == null)
            return;

        mCustomView.setVisibility(View.GONE);
        mTargetView.removeView(mCustomView);
        mCustomView = null;
        mTargetView.setVisibility(View.GONE);           
        mCustomViewCallback.onCustomViewHidden();           
        mContentView.setVisibility(View.VISIBLE);
    }

    @Override
    public boolean onConsoleMessage(ConsoleMessage consoleMessage) {
        return super.onConsoleMessage(consoleMessage);
    }
}

我正在onshowcustomview（）的第1行获得NPE。该视频不会全屏显示。提前致谢