使用cookie实现永久登陆
1，在cookie里面保存账号密码然后和数据库核对（由于我没有使用数据库，就不用了
2，在cookie里面保存时间戳和账号使用加密解密（我也没有使用时间戳
思路，request.getParameter("account");,获得账号，存入cookie，加入时间戳重定制网页内容
由于重定制的关系，这个时候我们不能用getParameter了，只能在cookie获得资料
原码
<%@page contentType="text/html"%> <%@page pageEncoding="UTF-8"%> <%!private static final String KEY = "huanggabin";public final static String getPassword(String a) {return a;}%> <%request.setCharacterEncoding("UTF-8");response.setCharacterEncoding("UTF-8");String action = request.getParameter("action");if ("login".equals(action)) {String account = request.getParameter("account");String account2 = request.getParameter("account");System.out.println(account2);String password = request.getParameter("password");int timeout = Integer.parseInt(request.getParameter("timeout"));String ssid = getPassword(account + KEY);Cookie accountCookie = new Cookie("account", account);accountCookie.setMaxAge(timeout);Cookie ssidCookie = new Cookie("ssid", ssid);ssidCookie.setMaxAge(timeout);response.addCookie(accountCookie);response.addCookie(ssidCookie);response.sendRedirect(request.getRequestURI() + "?"+ System.currentTimeMillis());return;} else if ("logout".equals(action)) {Cookie accountCookie = new Cookie("account", "");accountCookie.setMaxAge(0);Cookie ssidCookie = new Cookie("ssid", "");ssidCookie.setMaxAge(0);response.addCookie(accountCookie);response.addCookie(ssidCookie);response.sendRedirect(request.getRequestURI() + "?"+ System.currentTimeMillis());return;}boolean login = false;String account = null;String ssid = null;if (request.getCookies() != null) {for (Cookie cookie : request.getCookies()) {if (cookie.getName().equals("account")) {account = cookie.getValue();}if (cookie.getName().equals("ssid")) {ssid = cookie.getValue();}}}if (account != null && ssid != null) {login = ssid.equals(getPassword(account + KEY));} %> <%String account2 = request.getParameter("account");//System.out.println(account2); %> <!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>JSP Page</title> <script> alert(document.cookie); </script> </head> <body><%=login ? "欢迎回来" : "请先登录"%><br /><%if (login) {%>欢迎你!!!,<%=account%><a href="${pageContext.request.requestURI}?action=logout">注销</a><%} else {%><form action="${pageContext.request.requestURI}?action=login"method='post'>账号：<input type="text" name="account"><br /> 密码: <inputtype="text" name="password"><br /> 有效期： <input type="radio"name="timeout" value="-1">关闭浏览器失效<br /> <input type="radio"name="timeout" value="<%=30 * 24 * 60 * 60%>">30天有效<br /> <inputtype="radio" name="timeout" value="<%=Integer.MAX_VALUE%>">永久有效<br /><input type="submit" value="登陆 " class="button"></form><%}%> </body> </html>