jsp之登陆页面和cookie

功能：简单的登陆程序，进入首页as1.jsp，如果是首次登陆，跳转到登陆界面login.jsp，成功后，保存cookie，跳转到index.jsp，设置flag，再回到as1.jsp

as1.jsp

<%@ page language="java" import="java.util.*" pageEncoding="gb2312"%>
  <%

  if(session.getAttribute("flag") != null && session.getAttribute("flag").equals("ok")){
    out.print("<h1>welcome.</h1>");
  }else{
%>
  <jsp:forward page="login.jsp"/>

<% } %>

注意这里的else不可以省略大括号，否则算代码不完整，无法执行

<%@ page language="java" import="java.util.*" pageEncoding="gb2312"%>
<%
  String pName = request.getParameter("name");
  String pLove = request.getParameter("love");
  Cookie[] cookies = request.getCookies();
  if(pName != null){
    Cookie c = new Cookie("name",pName);
    c.setMaxAge(300);
    response.addCookie(c);
  }else{
    if(cookies != null){
      for(int i = 0;i<cookies.length;i++){
        if(cookies[i].getName().equals("name")){
          pName = cookies[i].getValue();
        }
      }
    }
  }

  if(pLove != null){
    Cookie c = new Cookie("love",pLove);
    c.setMaxAge(300);
    response.addCookie(c);
  }else{
    if(cookies != null){
      for(int i = 0;i<cookies.length;i++){
        if(cookies[i].getName().equals("love")){
          pLove = cookies[i].getValue();
        }
      }
    }
  }

%>


<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
  </head>

  <body>
     <h1 align="center">测试cooki</h1>
  <hr>

  <form action="index.jsp" method='post'>
   姓名:<input type='text' name='name' value='<%=pName%>'><br>
   兴趣:<input type='text' name='love' value='<%=pLove%>'> 
       <input type='submit' value='tijiao'>
   </form>
  </body>
</html>

index.jsp

<%@ page language="java" import="java.util.*" pageEncoding="gb2312"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
  </head>

    <body>
     <%
    if(request.getParameter("name").equals("admin") && request.getParameter("love").equals("123")){
    System.out.println("2222");
    session.setAttribute("flag","ok");
    session.setMaxInactiveInterval(-1);
    %>
    <jsp:forward page="as1.jsp"/>
 <%  }
    else{
      out.print("<h1>error msg</h1>");
    }
 %>
  </body>
</html>

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jsp之登陆页面和cookie

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