如何获取进度条以显示在xwalkview片段中

Question

首先，我想说明一下我是android studio的新手。我设法将xwalkview集成到一个片段中，效果很好，但是我的问题是进度条没有显示。我尽了我所能，但无济于事。对于如何使进度条显示的任何帮助，将不胜感激。

xwalk的片段 fragent.java

public class Flight extends Fragment {
public XWalkView  xWalkWebView;
public String lang;
ProgressBar progressBar;
private FrameLayout frameLayout;
private SwipeRefreshLayout swipe;
private AdView mAdView;


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

    View rootView = inflater.inflate(R.layout.flight, container, false);

    progressBar = (ProgressBar)rootView.findViewById(R.id.progressBar);
    // progressBar.setMax(100); // 100 maximum value for the progress value
    //  progressBar.setProgress(50); // 50 default progress value for the progress bar
    if (!DetectConnection.checkInternetConnection(getActivity())) {
        Toast.makeText(getApplicationContext(), getString(R.string.app_internet), Toast.LENGTH_SHORT).show();
    } else  {

        lang = Locale.getDefault().getLanguage();

        xWalkWebView=(XWalkView)rootView.findViewById(R.id.xwalkWebView);

        // XWalkPreferences.setValue(XWalkPreferences.REMOTE_DEBUGGING, true);

        //xWalkWebView.setResourceClient(new ResourceClient(xWalkWebView));
        xWalkWebView.setResourceClient(new XWalkResourceClient(xWalkWebView){
                                        @Override
                                        public void onLoadFinished(XWalkView view, String url) {
                                            super.onLoadFinished(view, url); // Stop your progress bar here
                                        }
                                        });

        xWalkWebView.load("http://example.com/?locale=" + lang, null);


    }
    return  rootView;
}


}

layout.xml

         <?xml version="1.0" encoding="utf-8"?>
         <org.xwalk.core.XWalkView
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/xwalkWebView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >
        <FrameLayout android:id="@+id/framelayout"
            android:layout_width="match_parent"
            android:layout_height="3dp"
            android:background="@android:color/transparent"
            android:visibility="visible">

        </FrameLayout>
        <ProgressBar android:id="@+id/ProgressBar"
            style="@android:style/Widget.DeviceDefault.Light.ProgressBar.Large"
            android:layout_width="match_parent"
            android:layout_height="4dp"
            android:layout_gravity="top"
            android:layout_marginTop="3dp"
            android:background="@android:color/transparent"
            android:progress="10" />
        </org.xwalk.core.XWalkView>