如何在Android Web View中显示进度条以显示外部存储设备中的Html5文件？

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <WebView
        android:id="@+id/webview"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <ProgressBar
        android:id="@+id/progressBar"
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:indeterminate="false"
        android:max="100"
        android:progress="0" />

</RelativeLayout>

WebView webView = findViewById(R.id.webview);
ProgressBar progressBar = findViewById(R.id.progressBar);

webView.setWebChromeClient(new WebChromeClient() {
    public void onProgressChanged(WebView view, int progress) {
        progressBar.setProgress(progress);
        if (progress == 100) {
            progressBar.setVisibility(View.GONE);
        } else {
            progressBar.setVisibility(View.VISIBLE);
        }
    }
});

// 加载外部存储设备中的HTML5文件
String filePath = Environment.getExternalStorageDirectory() + "/path/to/html5/file.html";
webView.loadUrl("file://" + filePath);