从 WebView Android 中的 URL 获取 Cookie

问：

我正在尝试在 android Web 视图中从 URl 获取 cookie。但总是得到 null.. 这是我的代码

 public String getCookie(WebView mWebView, String siteName,String cookieName){
        String CookieValue = null;

        CookieManager cookieManager = CookieManager.getInstance();
        cookieManager.setAcceptThirdPartyCookies(mWebView, true);
        String cookies = cookieManager.getCookie(siteName);
        String[] temp=cookies.split(";");
        for (String ar1 : temp ){
            if(ar1.contains(cookieName)){
                String[] temp1=ar1.split("=");
                CookieValue = temp1[1];
                break;
            }
        }
        return CookieValue;
    }