java防止盗链

jsp页面代码：指向一个servlet

url为：http://localhost:9090/servletDay3/index.jsp

aa

servlet中代码：

public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setCharacterEncoding("GBK");
		String referer = request.getHeader("referer");//  http://localhost:9090/servletDay3/index.jsp  表示从哪个页面访问到这个servlet的
		String nativeServerName = request.getServerName();//localhost
		System.out.println(nativeServerName);
		if(!"127.0.0.1".equals(nativeServerName)){
			response.getWriter().println("当前连接非本网站连接，请访问www.baidu.com");
		}
}