Android JS警告/确认不在棒棒糖5.1中工作

Question

这是我的代码，在PRE棒棒糖中运行良好。

public static void alertWebView(String url, Context c) {

     final WebView webView  = new WebView(c.getApplicationContext());
     webView.clearCache(true);
     webView.clearHistory();
     webView.getSettings().setJavaScriptEnabled(true);
     webView.getSettings().setJavaScriptCanOpenWindowsAutomatically(true);
     webView.getSettings().setDefaultTextEncodingName("utf-8");
     webView.getSettings().setPluginState(PluginState.ON);
     webView.setOnLongClickListener(new OnLongClickListener() {
         @Override
         public boolean onLongClick(View v) {
             return true;
         }
     });
     webView.setLongClickable(false);

     AlertDialog.Builder builder = new AlertDialog.Builder(c);
     builder.setInverseBackgroundForced(true);

     builder.setPositiveButton("Bezár", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface arg0, int arg1) {
        }
     }).setView(webView);

     final AlertDialog dialog = builder.create();

     webView.setWebChromeClient(new WebChromeClient() {
           @Override
           public boolean onJsAlert(WebView view, String url, String message, JsResult result) {
                return super.onJsAlert(view, url, message, result);
           }
     });

     webView.setWebViewClient(new WebViewClient() {
       public void onPageFinished(WebView view, String url) {
       }
     });

     webView.loadUrl(url);
     mHandler.postDelayed(new Runnable() {
            @Override
            public void run() {
                dialog.show();                  
            }
    }, 1000);

    dialog.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);

}

04-21 11：18：48.425：W / JsDialogHelper（3997）：无法创建对话框，WebView上下文不是活动

html是一个带有onclick和确认js对话框的按钮。