cookies的使用

Cookie 一般可以使用于用来记录客户访问网页的时间，用户购物等。

客户端访问服务器，服务器返回一个Cookie用于便于下次客户继续访问。

Cookie cookie = new Cookie("bookHistory", cookieValue);

//设置cookie的存活时间，单位为秒

cookie.setMaxAge(1*30*24*3600);

//设置访问路径
cookie.setPath("/WebProject1");

response.addCookie(cookie);

cookieValue即为返回的数据，而bookHistory是用于下次客户访问时候用于区别不同cookie的标志。

客户端接收cookie，接收的cookie为一个数组

Cookie cookie[] = request.getCookies();

package cn.itcast.cookie;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class CookieDemo1 extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        
        PrintWriter pw = response.getWriter();
        pw.print("<a href='/WebProject1/servlet/CookieDemo2'>清除上次访问时间</a><br/>");
        pw.print("你上次访问的时间:");
        
        //获取用户的时间
        Cookie cookie[] = request.getCookies();
        for(int i=0;i<cookie.length&&cookie!=null;i++){
        	if(cookie[i].getName().equals("LastAccessTime")){
        		long cookieValue = Long.parseLong(cookie[i].getValue());
        		Date date = new Date(cookieValue);
        		pw.print(date.toLocaleString());
        	}
        }
        
        //给用户回送最新的访问时间
        Cookie cookies = new Cookie("LastAccessTime", System.currentTimeMillis()+"");
        cookies.setMaxAge(1*30*24*3600);
        cookies.setPath("/WebProject1");
        
        response.addCookie(cookies);
        
	}

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

}