javaweb Cookie

分手后的思念是犯贱 2023-06-08 03:19 29阅读 0赞

Cookie就是服务器保存在客户端的数据,Cookie是由服务器创建，

package com.sheng.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;
    
    //显示上一次访问的时间
    //Cookie就是服务器保存在客户端的数据,Cookie是由服务器创建，
    public class Damo4Cookie extends HttpServlet {
    	
    	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		
    		 //设置服务器端以utf-8编码进行输出
    		 response.setCharacterEncoding("UTF-8");
    		 response.setContentType("text/html;charset=UTF-8");
    		 // 第一步.获得从客户端带过来的所有的Cookie:
    		 Cookie[] cookies=request.getCookies();
    		 PrintWriter out=response.getWriter();
    		 //如果用户是第一次访问，那么得到cookies将是null
    		 //第二步.从所有的Cookie中查找指定名称的Cookie：
    		 if (cookies!=null) {
    			 out.write("您上次访问的时间是：");
    			 for (int i = 0; i < cookies.length; i++) {
    				Cookie cookie=cookies[i];
    				if (cookie.getName().equals("lastAccessTime")) {
    					//第四步.记录当前的时间,并且利用Cookie将时间回写到浏览器端.  
    					Long lastAccesTime=Long.parseLong(cookie.getValue());
    					Date data=new Date(lastAccesTime);
    					out.write(data.toLocaleString());
    					System.out.println(cookies[0]);
    				}
    			}
    		}else {
    			out.write("这时您第一次访问本站");
    		}
    		 Cookie cookie=new Cookie("lastAccessTime", System.currentTimeMillis()+"");
    		 //将cookie对象添加到response对象中，这样，服务器在输出response对象内容就会将cookie对象给输出出去
    		 response.addCookie(cookie);
    	}
    
    	
    	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		
    		doGet(request, response);
    	}
    
    }