刪除cookies後重定向

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; 
     } 

我有這個servlet，當cookie被刪除時，它會重定向到index.html。我的問題是，當我刪除cookies時，它不會自動重定向到index.html，我需要在重定向之前先重新加載/刷新頁面。如何在刪除Cookie後自動重定向？

Answer 1

我相信你在刪除cookie時，頁面已經加載。您需要了解servlet的請求 - 響應週期。

只有當容器接收到新的請求時才執行Servlet。一旦你的頁面已經被加載，然後你清除了你的cookie，你的servlet將只會在頁面刷新時執行（或者一個新的請求將被髮送到servlet）。