login.jsp
<script type="text/javascript"> function _change(){ /* 1.得到img元素 2.修改其src为/SessionDemo/VeifyCodeServlet */ var imgEle = document.getElementById("img"); var v = new Date; var s = v.getTime(); //imgEle.src = "/SessionDemo/VeifyCodeServlet?a=" + new Date().getTime(); imgEle.src = "/SessionDemo/VeifyCodeServlet?a=" + s; } function _check(){ if(form1.username.value==""){ alert("用户名不能为空"); return; } if(form1.password.value==""){ alert("密码不能为空"); return; } if(form1.vCode.value==""){ alert("验证码不能为空"); return; } } </script> </head> <body> <h1>登录</h1> <% /* 读取名为uname的cookie，如果为空显示"",不为空显示cookie的值 */ String uname = ""; Cookie[] cs = request.getCookies(); // 获取请求中所有的cookie if(cs != null){ // cookie不为空 for(Cookie c : cs){ // 循环遍历Cookie[] if("uname".equals(c.getName())){ // 查找名称为uname的cookie uname = c.getValue(); // 将值赋给uname变量 } } } %> <% // 显示错误信息 String s = ""; String msg = (String) request.getAttribute("msg"); if (msg != null) { s = msg; } %> <%-- 本页面提供登录表单，还要显示错误信息 --%> <font color="red"><b><%=s%></b> </font> <form action="/SessionDemo/LoginServlet" method="post" name="form1"> 用户名：<input type="text" name="username" value="<%=uname%>" /><br /> 密   码：<input type="password" name="password" /><br /> 验证码：<input type="text" name="vCode" size="3"/> <img id="img" src="/SessionDemo/VeifyCodeServlet"> <a href="javascript: _change()">看不请，换一张</a> <br /> <input type="submit" value="登录" onclick="_check()"/> </form> </body>
succ1.jsp
<% String username = (String)session.getAttribute("username"); if(username==null){ /* * 向request域中保存错误信息，并转发到login.jsp */ request.setAttribute("msg", "你还没有登录"); request.getRequestDispatcher("/session2/login.jsp").forward(request, response); return; } %> <h1>succ1</h1> 欢迎<%=username %>访问本页面。 <a href="session2/exit.jsp">退出</a>
exit.jsp
<body> <% session.removeAttribute("username"); response.sendRedirect("login.jsp"); %> </body>
LoginServlet
package Demo_01; import java.io.IOException; import javax.servlet.RequestDispatcher; import javax.servlet.ServletException; import javax.servlet.http.Cookie; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; public class LoginServlet extends HttpServlet { public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { /* * 验证码处理 1.得到session里的验证码文本 2.获取到文本框中输入的文本 3.比较 */ String sessiontext = (String) request.getSession().getAttribute( "session_vcode"); String wtext = request.getParameter("vCode"); if (!wtext.equalsIgnoreCase(sessiontext)) { request.setAttribute("msg", "输入的验证码有误"); request.getRequestDispatcher("/session2/login.jsp").forward( request, response); return; } /* * 1、获取表单信息 */ // 中文处理 request.setCharacterEncoding("utf-8"); // 获取 String username = request.getParameter("username"); String password = request.getParameter("password"); /* * 2、校验用户名和密码是否正确 */ if (!"itcast".equalsIgnoreCase(username)) { // 成功 /* * 附加项：把用户名保存到cookie中，发送给客户端浏览器 * 当再次打开login.jsp时，login.jsp会读取request中的cookie，把它显示到用户名文本框中 */ Cookie cookie = new Cookie("uname", username);// 创建cookie cookie.setMaxAge(60 * 60 * 24);// 设置cookie名长为一天 response.addCookie(cookie);// 保存cookie /* * 3、如果成功 > 保存用户信息到session中 > 重定向到succ1.jsp */ HttpSession session = request.getSession();// 获取session对象 session.setAttribute("username", username);// 向session域中保存数据 response.sendRedirect("/SessionDemo/session2/succ1.jsp"); } else { // 失败 /* * 4、如果失败 > 保存错误数据到request域中 > * 转发到login.jsp（如果使用重定向request域中的数据就会因为第二次请求 而获取不到） */ request.setAttribute("msg", "用户名或密码错误"); RequestDispatcher rd = request .getRequestDispatcher("/session2/login.jsp"); rd.forward(request, response);// 转发 } } }
VeifyCodeServlet
package Demo_01; import java.awt.image.BufferedImage; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import Image.VerifyCode; public class VeifyCodeServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { /* * 1.生成图片 * 2.保存图片上的文本到session中 * 3.把图片响应给客户端 */ VerifyCode vc = new VerifyCode(); BufferedImage bi = vc.getImage(); request.getSession().setAttribute("session_vcode", vc.getText()); VerifyCode.output(bi, response.getOutputStream()); } }
其中还用到了VerifyCode.java一个生成验证码的类
