javaweb:Cookie

  1. Cookie的英文原意是"点心",它是用户访问Web服务器时,服务器在用户硬盘上存放的信息,好像是服务器送给客户的"点心" 。

   2. 服务器可以根据Cookie来跟踪用户,这对于需要区别用户的场合(如电子商务)特别有用。

   3. 一个Cookie包含一对Key/Value。

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 = "CookieServlet")
public class CookieServlet extends HttpServlet {
    private int count1;
    private int count2;

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

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Cookie cookie = new Cookie("CookieName"+count1++, "CookieValue"+count2++);
        cookie.setMaxAge(15); // 设置cookie的存活时间
        response.addCookie(cookie);  //  服务器给客户端发送一个Cookie

        Cookie[] cookies = request.getCookies(); // 获取客户端发送给服务器的Cookie
        if(null == cookies){
            return;
        }

        for(Cookie c : cookies){
            System.out.println(c.getName()+" "+c.getValue());
        }
    }
}