业务逻辑：
1、登陆login.jsp
2、判断登陆是否成功check.jsp
3、登陆成功页面newsDetail.jsp
4、登陆失败转发到login.jsp
代码如下：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>用户登陆页</title>
</head>
<body> <form action="check.jsp" method="post">
<table>
<tr>
<td>用户名：</td>
<td><input type="text" name="username"/></td>
</tr>
<tr>
<td>密码：</td>
<td><input type="text" name="pwd"/></td>
</tr>
<tr>
<td>邮箱：</td>
<td><input type="text" name="email" /></td>
</tr> <tr>
<td align="right"><input type="checkbox" name="title" value="10001" /></td>
<td>第一个选项</td>
</tr>
<tr>
<td align="right"><input type="checkbox" name="title" value="10002" /></td>
<td>第二个选项</td>
</tr>
<tr>
<td align="right"><input type="checkbox" name="title" value="10004" /></td>
<td>第三个选项</td>
</tr> <tr>
<td align="right"><input type="submit" value="提交" /></td>
</tr>
</table>
</form>
<%
Object obj = request.getAttribute("error");
if(obj!=null){
out.println("info=>>>>>>"+obj.toString());
}
%> </body>
</html>
check.jsp
<%@ page language="java" import="java.util.*" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>"> <title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
</head> <body>
<%
//获取表单提写数据
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
String username = request.getParameter("username");
String password = request.getParameter("pwd");
String email = request.getParameter("email");
/* 获取checkbox的值*/
String[] titles = request.getParameterValues("title");
String alltitle="";
if(titles!=null && titles.length!=0){
for(int i=0;i<titles.length;i++){
alltitle += titles[i]+" ";
}
}
//判断登陆是否成功
if(!username.equals("admin")){
request.setAttribute("error", "登陆失败！");
request.getRequestDispatcher("login.jsp").forward(request, response); }else{
//登陆成功，创建session会话，保存登陆状态
session.setAttribute("username", username);
session.setAttribute("password", password);
//session设置过期时间
session.setMaxInactiveInterval(5);
response.sendRedirect("newsDetail.jsp"); } %>
</body>
</html>
newsDetail.jsp
<!--页面的头部-->
<div id="header">
<!--页面顶部-->
<div class="main-top">
<div class="logo"><a href=""><span>新闻大视野</span></a></div>
<div class="login-box">
<%
Object obj=session.getAttribute("username");
Object pwd=session.getAttribute("password");
String username="";
String password="";
if(obj!=null &&pwd!=null){
username = obj.toString();
password = pwd.toString();%>
<label><%="欢迎你，"+username %></label> <a href="logout.jsp">注销</a>
<% }else{%>
<label>用户名</label><input type="text" name="username"/><label>密码</label><input type="text" name="password"/><button>登录</button>
<%}%> </div>