删除 cookie 时重定向

Question

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.setContentType("text/html"); //setting the MIME of this page

    PrintWriter out = response.getWriter(); //creating a writer object          
        String sourceCookieName = "Username"; 
        String sourceCookieName2 = "Password"; 
        Cookie targetCookie = null;
        Cookie targetCookie2 = null;
        Cookie[] allCookies = request.getCookies();

        if (allCookies!=null) {
            for (Cookie cookie : allCookies) {
                if (cookie.getName().equals(sourceCookieName)) {
                    targetCookie = cookie;
                    //break;
                }
                if (cookie.getName().equals(sourceCookieName2)) {
                    targetCookie2 = cookie;
                    //break;
                }
            }
        }
        if (targetCookie != null && targetCookie2 != null) {
            //somecode
        } 
        else {
            out.print("<p><h1>You will be redirected in <span id='counter'>5</span> second(s).</h1></p>");
            out.print("<script type='text/javascript'>");
            out.print("function countdown() {");
            out.print("var i = document.getElementById('counter');");
            out.print("if (parseInt(i.innerHTML)<=1) {");
            out.print("location.href = 'index.html';");
            out.print("}");
            out.print("i.innerHTML = parseInt(i.innerHTML)-1;");
            out.print("}");
            out.print("setInterval(function(){ countdown(); },1000);");
            out.print("</script>");
            //response.sendRedirect("index.html");
            return;
        }

我有这个 servlet，它会在 cookie 被删除时重定向到 index.html。我的问题是，当我删除 cookie 时，它​​不会自动重定向到 index.html 我需要在重定向之前先重新加载/刷新页面。删除 cookie 后如何使其自动重定向？

Answer 1

我相信您在页面已加载时正在删除 cookie。您需要了解 servlet 的请求-响应周期。

只有在容器收到新请求时才会执行 Servlet。一旦您的页面已经加载，然后您清除了 cookie，您的 servlet 将仅在页面刷新时执行（或者将向 servlet 发送新请求）。