Cookie:小甜点 , 是客户端技术,将我们的共享数据保存到客户端(浏览器) 后面再请求的时候就会将共享数据发送到服务器.
此Cookie的作用就是 :我打个比方, 就是你去超市买东西,而你想要优惠的话就必须要办会员卡,而这会员卡就想Cookie,你下次再进来买东西就只要带会员卡就能证明你的身份了.
看了我上一张博客是有结构的,不懂结构的话可能会有点蒙:
@WebServlet("/cookie/login") public class LoginServlet extends HttpServlet{ private static final long serialVersionUID = 1L; protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //设置请求格式 req.setCharacterEncoding("utf-8"); //设置响应格式 resp.setContentType("text/html;charset=utf-8"); PrintWriter out = resp.getWriter(); //获取请求时的用户名和密码 String username = req.getParameter("username"); String password = req.getParameter("password"); //创建Cookie对象 这是重点 Cookie c = new Cookie("username",username); resp.addCookie(c); //验证用户名和密码 在此我账号密码写死 if("admin".equals(username)&&"1234".equals(password)){ //进入邮箱界面 out.println("<h1>欢迎登录:"+username+"的邮箱</h1>"); out.println("<a href='/dowork/cookie/list'>未读邮件</a>"); }else{ System.out.println("登录失败"); } //关闭流 out.close(); } } @WebServlet("/cookie/list") public class ListServlet extends HttpServlet{ private static final long serialVersionUID = 1L; @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //设置请求的格式 req.setCharacterEncoding("utf-8"); //设置响应格式 resp.setContentType("text/html;charset=utf-8"); //获取cookie Cookie[] cookies = req.getCookies(); String username = null; for (Cookie cookie : cookies) { if("username".equals(cookie.getName())){ username = cookie.getValue(); } } PrintWriter out = resp.getWriter(); out.println("欢迎查看:"+username+"邮件"); out.println("<a href = '/dowork/cookie/content'>邮件1</a>"); out.println("<a href = '/dowork/cookie/content'>邮件2</a>"); out.println("<a href = '/dowork/cookie/content'>邮件3</a>"); out.close(); } } /** * * @author AfricaYoung * @Date 2016-08-15 */ @WebServlet("/cookie/content") public class ContentServlet extends HttpServlet{ private static final long serialVersionUID = 1L; @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { req.setCharacterEncoding("utf-8"); String username = null; Cookie[] cookies = req.getCookies(); for (Cookie cookie : cookies) { if("username".equals(cookie.getName())){ username = cookie.getValue(); } } resp.setContentType("text/html;charset=utf-8"); PrintWriter out = resp.getWriter(); out.print("最后一页啦:"+username+"大大"); out.print("<br/>宝宝炸了"); out.close(); } }Cookie 的缺陷: 1.Cookie中的共享数据的类型只能是String类型,如果需要共享多个数据,就需要创建多个Cookie对象,很麻烦 2.Cookie不支持中文 3.Cookie是保存在浏览器中,不安全 4.Cookie有数据大小的限制,一个Cookie支持4kb 一个浏览器中只能保存300个Cookie信息 一个应用在一个浏览器中最多保存20个Cookie
Session:会话,在浏览器打开的时候创建,浏览器关闭的时候销毁 是一个服务端的技术,将共享数据保存在服务器中 Session底层就是Cookie
/** * * @author AfricaYoung * @Date 2016-08-15 */ @WebServlet("/session/login") public class LoginServlet extends HttpServlet { private static final long serialVersionUID = 1L; @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // 设置请求格式 req.setCharacterEncoding("utf-8"); // 设置响应格式 resp.setContentType("text/html;charset=utf-8"); PrintWriter out = resp.getWriter(); // 获取请求时的用户名和密码 String username = req.getParameter("username"); String password = req.getParameter("password"); // 获取session HttpSession session = req.getSession(); session.setAttribute("USERNAME_IN_SESSION", username); // 修改共享数据 // 验证用户名和密码 if ("admin".equals(username) && "1234".equals(password)) { // 进入邮箱界面 out.println("<h1>欢迎登录:" + username + "的邮箱</h1>"); out.println("<a href='/dowork/session/list'>未读邮件</a>"); // URL重写(浏览器可以禁用Cookie,这样我们的jsessionid就不能保存在浏览器中,那么服务器中的数据也就获取不到) // 方式:使用URL重写,自动的根据浏览器是否禁用Cookie来拼接jsessionid String url = resp.encodeURL("/dowork/session/list"); out.print("<a href='" + url + "'>收件箱(4)</a><br/>"); } else { System.out.println("登录失败"); } out.close(); } } @WebServlet("/session/list") public class ListServlet extends HttpServlet{ private static final long serialVersionUID = 1L; @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //设置请求的格式 req.setCharacterEncoding("utf-8"); //设置响应格式 resp.setContentType("text/html;charset=utf-8"); String username = (String) req.getSession().getAttribute("USERNAME_IN_SESSION"); PrintWriter out = resp.getWriter(); out.println("欢迎查看:"+username+"邮件"); out.println("<a href = '/dowork/session/content'>邮件1</a>"); out.println("<a href = '/dowork/session/content'>邮件2</a>"); out.println("<a href = '/dowork/session/content'>邮件3</a>"); out.close(); } } @WebServlet("/session/content") public class ContentServlet extends HttpServlet{ private static final long serialVersionUID = 1L; @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { req.setCharacterEncoding("utf-8"); String username = (String) req.getSession().getAttribute("USERNAME_IN_SESSION"); resp.setContentType("text/html;charset=utf-8"); PrintWriter out = resp.getWriter(); out.print("最后一页啦:"+username+"大大"); out.print("<br/>宝宝炸了"); out.close(); } }