案例：记录上一次的访问时间

た入场券 2022-12-23 06:17 143阅读 0赞

# 1、分析 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3ZsdWNreV9sb25n_size_16_color_FFFFFF_t_70_pic_center]

# 2、实现步骤 #

●设置浏览器响应内容类型和编码

●获取客户端携带的cookie

●判断key为time的cookie是否存在

●存在  
  ■获取value值，响应给浏览器  
  ■覆盖cookie，更新值

●不存在  
  ■响应给浏览器，比如：“你是首次访问”  
  ■创建cookie，并且发送cookie到客户端

# 3、代码实现 #

package com.bdit;
    
    import javax.servlet.http.Cookie;
    
    public class DBCookie {
        
        public static Cookie getCookie(Cookie[] cookies,String cookiekey){
        
            if(cookies!=null&&cookies.length>0){
        
                for(Cookie cookie:cookies){
        
                    if(cookie.getName().equals(cookiekey)){
        
                        return cookie;
                    }
                }
            }
            return null;
        }
    }

package com.bdit;
    
    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;
    import java.time.LocalDateTime;
    
    @WebServlet(urlPatterns = {
        "/cookieServlet04"})
    public class CookieServlet04 extends HttpServlet {
        
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
            doGet(request,response);
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
            request.setCharacterEncoding("utf-8");
            response.setContentType("text/html;charset=UTF-8");
            Cookie key=DBCookie.getCookie(request.getCookies(),"key");
            if(key!=null){
        
               String result=key.getValue();
               response.getWriter().print("你上次访问的时间是："+result);
            }else{
        
                response.getWriter().print("<h2>第一次访问</h2>");
            }
            String date=LocalDateTime.now().toString();
            Cookie cookie=new Cookie("key",date);
            cookie.setPath(request.getContextPath());
            cookie.setMaxAge(60*60*24*5);
            response.addCookie(cookie);
        }
    }

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