防盗链模拟

public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        response.setContentType("text/html;charset=utf-8");
        String referer = request.getHeader("Referer");
        if (referer == null) {//通过地址栏盗链
            response.sendError(404);
            return;
        } else if (!referer.contains(getServletContext().getContextPath())) {// 通过超链接盗链
            response.sendError(500, "你这个可耻的链接小偷");
            return;
        }
        response.getWriter().print("下载成功");
    }