Servlet中Cookie实用示例（含删除）

使用Cookie 显示/清除 上次访问时间

效果图

用于设置并显示cookie的servlet代码，注意：第一次访问时由于没有历史cookie所以不会显示时间，只会新建cookie，此时刷新可以看到上次登录时间

package ser.david;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date;

public class CookieDemo extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        PrintWriter out = response.getWriter();
        out.print("<a href='/delcookie'>清除上次访问时间</a><br/>");//输出跳转到删除cookie的servlet按钮
        out.print("您上次访问的时间是：");

        //获取cookie
        Cookie cookies[] = request.getCookies();
        for (int i = 0; cookies != null && i < cookies.length; i++) {
            if (cookies[i].getName().equals("lastAccessDate")) {
                long longtime = Long.parseLong(cookies[i].getValue());
                Date date = new Date(longtime);
                out.print(date.toLocaleString());

            }
        }
        //设置最新的时间cookie
        Cookie cookie = new Cookie("lastAccessDate", System.currentTimeMillis() + "");
        cookie.setMaxAge(30 * 24 * 3600);//过期时间
        cookie.setPath("/cookie");//作用于当前页面
        response.addCookie(cookie);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

}

用于删除cookie的servlet代码

package ser.david;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet(name = "DeleteCookie")
public class DeleteCookie extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Cookie cookie=new Cookie("lastAccessDate",System.currentTimeMillis()+"");
        cookie.setMaxAge(0);//删除
        cookie.setPath("/cookie");
        response.addCookie(cookie);
        response.sendRedirect("/cookie");//**重定向回到显示cookie的页面，可以看到页面上已经不显示上次访问的时间，但是！！！由于我们又访问了一次cookie页面，给服务器重新发送了一个请求，所以实际上又生成了新的cookie（加载页面后），刷新可看到**
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    }

}

相关配置文件代码

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">

    <servlet>
        <servlet-name>cookie</servlet-name>
        <servlet-class>ser.david.CookieDemo</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>cookie</servlet-name>
        <url-pattern>/cookie</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>delCookie</servlet-name>
        <servlet-class>ser.david.DeleteCookie</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>delCookie</servlet-name>
        <url-pattern>/delcookie</url-pattern>
    </servlet-mapping>
</web-app>