Servlet2

//创建Cookie对象

        Cookie userNameCookie = new Cookie("userName",userName);

        Cookie userPasswordCookie = new Cookie("userPassword",userPassword);

//返回给访问对象

        resp.addCookie(userNameCookie);

        resp.addCookie(userPasswordCookie);

/、对外部浏览器返回的响应头进行处理

        Cookie[] cookies = req.getCookies();

        if(cookies != null){

            for(Cookie cookie:cookies){



                if (cookie.getName().equals("userName"))

                {

                    userName = cookie.getValue();

                }else if (cookie.getName().equals("userPassword")) {

                    userPassword = cookie.getValue();

                }

            }

        }

		if("admin".equals(userName) && "123".equals(password)){

			//获取cookie last-name --- >

			Cookie [] cookies = request.getCookies();

			

			//从数组里面找出我们想要的cookie

			Cookie cookie = CookieUtil.findCookie(cookies, "last");

			

			//是第一次登录，没有cookie

			if(cookie == null){

				

				Cookie c = new Cookie("last", System.currentTimeMillis()+"");

				c.setMaxAge(60*60); //一个小时

				response.addCookie(c);

				

				response.getWriter().write("欢迎您, "+userName);

				

			}else{

				//1. 去以前的cookie第二次登录，有cookie

				long lastVisitTime = Long.parseLong(cookie.getValue());

				

				//2. 输出到界面，

				response.getWriter().write("欢迎您, "+userName +",上次来访时间是："+new Date(lastVisitTime));

                

				//3. 重置登录的时间

				cookie.setValue(System.currentTimeMillis()+"");

				response.addCookie(cookie);

			}

		}else{

			response.getWriter().write("登陆失败 ");

		}

Cookie[] cookies = request.getCookies();

Cookie cookie = CookieUtil.findCookie(cookies,"history");

//如果cookie是空的,表img01明没有浏览任何商品

if(cookie == null){

    out.println("你还没有浏览任何商品");

}else{

    //不是空,表明有浏览记录

    String[] ids = cookie,getValue().split("#");

    for(String id:ids){

        //输出浏览记录

    }

}

		Cookie cookie = new Cookie("history","");

		cookie.setMaxAge(0); //设置立即删除

		cookie.setPath("/CookieDemo02");

		response.addCookie(cookie);

		//得到会话ID

		String id = session.getId();

		

		//存值

		session.setAttribute(name, value);

		

		//取值

		session.getAttribute(name);

		

		//移除值

		session.removeAttribute(name);

//创建session

        HttpSession session = req.getSession();

//把表单数据放入session中

        String sessioname = (String) session.getAttribute("userName");

       

//查看一下二次登录的session

        if(sessioname != null){

            System.out.println("second Session:");

        }

		response.setContentType("text/html;charset=utf-8");

			

			//1. 获取要添加到购物车的商品id

			int id = Integer.parseInt(request.getParameter("id")); // 0 - 1- 2 -3 -4 

			String [] names = {"Iphone7","小米6","三星Note8","魅族7" , "华为9"};

			//取到id对应的商品名称

			String name = names[id];

			

			//2. 获取购物车存放东西的session  Map<String , Integer>  iphoen7 3

			//把一个map对象存放到session里面去，并且保证只存一次。 

			Map<String, Integer> map = (Map<String, Integer>) request.getSession().getAttribute("cart");

			//session里面没有存放过任何东西。

			if(map == null){

				map = new LinkedHashMap<String , Integer>();

				request.getSession().setAttribute("cart", map);

			}

			

			//3. 判断购物车里面有没有该商品

			if(map.containsKey(name)){

				//在原来的值基础上  + 1 

				map.put(name, map.get(name) + 1 );

			}else{

				//没有购买过该商品，当前数量为1 。

				map.put(name, 1);

			}

			

			//4. 输出界面。（跳转）

			response.getWriter().write("<a href='product_list.jsp'><h3>继续购物</h3></a><br>");

			response.getWriter().write("<a href='cart.jsp'><h3>去购物车结算</h3></a>");

//强制干掉会话，里面存放的任何数据就都没有了。

session.invalidate();

//从session中移除某一个数据

//session.removeAttribute("cart");

//3中请求转发的方式

        RequestDispatcher rd = req.getRequestDispatcher("/ServletForwardExample/*");//1

        rd = this.getServletContext().getNamedDispatcher("servletForwardExample");//2

        rd = this.getServletContext().getRequestDispatcher("/servletForwardExample/*");//3

        rd.forward(req,resp);

public class TestFilter implements Filter{



// 可以像servlet配置一样，对TestFilter的init传入FilterConfig filterConfig

    @Override

    public void init(FilterConfig filterConfig) throws ServletException {}



    @Override

    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {}



    @Override

    public void destroy() {}

}

<filter>

        <init-param>

            <param-name>filterParam</param-name>

            <param-value>euraxluo</param-value>

        </init-param>

        <filter-name>testFilter</filter-name>

        <filter-class>com.controller.filter.TestFilter</filter-class>

    </filter>



    <filter-mapping>

        <filter-name>testFilter</filter-name>

        <url-pattern>/testFilter/*</url-pattern>

    </filter-mapping>

//通过判断是否有session来判断是否登录

        HttpSession session = req.getSession();

        if(session.getAttribute("userName")==null){

            HttpServletResponse resp = (HttpServletResponse)servletResponse;

            resp.sendRedirect("/GetPostServlet/*");

        }else{

            filterChain.doFilter(servletRequest,servletResponse);

        }

public class TestListener implements HttpSessionAttributeListener, ServletContextListener, ServletRequestListener {}

<listener>

        <listener-class>com.controller.listener.TestListener</listener-class>

    </listener>

synchronized(this){

    //代码块

}