组合WebView和ProgressBar

想给WebView加一个进度条，结果发现android的文档中“Building Custom Components”提到的R.styleable这个类已经不能用了。我不想加xml配置，还没有找到什么好方法能处理初始化时的attrs。进度条在顶部固定显示在试了半天之后倒是弄好了。

@SuppressWarnings("deprecation")
public class ProgressWebView extends WebView {

   private ProgressBar progressbar;

   public ProgressWebView(Context context, AttributeSet attrs) {
       super(context, attrs);
       progressbar = new ProgressBar(context, null, android.R.attr.progressBarStyleHorizontal);
       progressbar.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, 3, 0, 0));
       addView(progressbar);
       setWebViewClient(new WebViewClient());
       setWebChromeClient(new WebChromeClient());
   }

   public class WebChromeClient extends android.webkit.WebChromeClient {
       @Override
       public void onProgressChanged(WebView view, int newProgress) {
           if(newProgress == 100) {
               progressbar.setVisibility(GONE);
           } else {
               if(progressbar.getVisibility() == GONE)
                   progressbar.setVisibility(VISIBLE);
               progressbar.setProgress(newProgress);
           }
           super.onProgressChanged(view, newProgress);
       }
   }
 
   @Override
   protected void onScrollChanged(int l, int t, int oldl, int oldt) {
       LayoutParams lp = (LayoutParams) progressbar.getLayoutParams();
       lp.x = l;
       lp.y = t;
       progressbar.setLayoutParams(lp);
       super.onScrollChanged(l, t, oldl, oldt);
   }
}