JSP的Cookie操作

快来打我* 2021-09-30 08:06 304阅读 0赞

**一 点睛**

Cookie的本意是“小甜饼”，然而在互联网上，只能用其寓意，它指的是客户端计算机上保存的浏览器最爱吃的一段文本。这段文本在网络服务器上生存，并发给浏览器。可以通过Cookie识别用户身份，记录用户名和密码，跟踪重复用户等。浏览器将Cookie通过健值对的形式，保存到客户端的某个指定目录之中。但是Cookie的安全性不高，但很便利。通常便利都是牺牲安全换来的。

**二 实战**

1 通过Cookie保存并读取用户的登录信息

<%@ page contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
    <html>
        <head>
            <meta http-equiv="Content-Type" contentType="text/html; charset=UTF-8">
            <title>Cookie使用范例</title>
        </head>
        <body>
        <%          
            Cookie[] cookies = request.getCookies();
            String user = "";
            String pwd = "";
            String date = "";
            if (cookies != null)
            {
                for (int i = 0; i < cookies.length; i++)
                {
                    if(cookies[i].getName().equals("uid"))
                        user = cookies[i].getValue();
                     if(cookies[i].getName().equals("password"))
                        pwd = cookies[i].getValue();
                     if(cookies[i].getName().equals("date"))
                        date = cookies[i].getValue();               
                }
            }
            if ("".equals(user) && "".equals(date)){
        %>
        游客您好，欢迎您的到来！请您注册。
            <form name="form1" method="post" action="cookieDeal.jsp">
                用户名： <input    name="name" type="text" id="name" style="width: 120px">
                密   码： <input name="pwd" type="password" id="pwd" style="width: 120px">
                
                <input type="submit" name="Submit" value="提交">
            </form>
        <%
            }else{           
        %>  
            欢迎您[<b><%=user%></b>]再次光临
            您注册时间是：  <%=date%>
        <%}%>   
        </body>
    </html>

2 向Cookie写入信息

<%@ page contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
    <%@ page import="java.util.*"%>
    <%@ page import="java.text.*"%>
    <html>
        <head>
            <meta charset="UTF-8">
            <title>写入Cookie</title>
        </head>
        <body>
        <%       
            String datetime=new SimpleDateFormat("yyyy-MM-dd").format(Calendar.getInstance().getTime()); //获取系统时间
            request.setCharacterEncoding("UTF-8");
            String user = request.getParameter("name");
            String pwd = request.getParameter("pwd");
            Cookie c1 = new Cookie("uid",user) ;
            Cookie c2 = new Cookie("password",pwd) ;
            Cookie c3 = new Cookie("date",datetime) ;
            response.addCookie(c1) ;
            response.addCookie(c2) ;
            response.addCookie(c3) ;
            c1.setMaxAge(60*60*24*10);
            c2.setMaxAge(60*60*24*10);
            c3.setMaxAge(60*60*24*10);
        %>
        <script type "text/javascript">window.location.href="login.jsp"</script>
        </body>
    </html>

**三 运行**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70 1][]

**四 说明**

这里读Cookie用到了request.getCookies()函数，写Cookie用到了response.addCookie(c)函数。

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