如何设置WebView使得加载网页时能够执行JavaScript脚本中的alert()函数

    public void loadHTML(){
        WebView wv = new WebView(this );
        WebSettings ws = wv.getSettings();
         ws.setJavascriptEnabled(true );
         //设置这个是为了保证在Javascript中alert的对话框时能显示
        wv.setWebChromeClient( new WebChromeClient(){
             @Override
             public boolean onJsAlert(WebView view, String url, String message,
                    JsResult result) {
                 // TODO Auto-generated method stub
                 return super .onJsAlert(view, url, message, result);
            }
        });
        wv.loadUrl("file:///android_asset/test.html" );
        setContentView(wv);
    }