本文主要是将Servlet中编写的用户管理系统用JSP来编写，注意比较Servlet和JSP的异同点。
现在还先将使用Model1模式来编写，以后再进行改进。
将涉及的知识点：
- 如何在JSP页面中进行转跳
- JSP如何操作数据库
- JSP中如何显示数据和进行分页
代码如下：
登录页面代码：
<%@ page language="java" contentType="text/html; charset=gb2312"
pageEncoding="gb2312"%>
<!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=gb2312">
<title>用户登录系统</title>
</head>
<body>
<center>
用户登录系统<br>
<hr>
<form action="loginCl.jsp" method="post">
用户名：<input type="text" name="username"><br>
密 码：<input type="password" name="passwd"><br>
<input type="submit" value="login">
<input type="reset" value="重置">
</form>
<hr>
</center>
</body>
</html>
登录业务处理代码：
<%@ page language="java" contentType="text/html; charset=gb2312" import="java.sql.*"
pageEncoding="gb2312"%>
<!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=gb2312">
<title>处理页面</title>
</head>
<body>
<%
//接收用户名和密码，完成对用户的验证
String u = request.getParameter("username");
String p = request.getParameter("passwd");
//到数据库中进行验证
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
Connection ct = DriverManager.getConnection("jdbc:sqlserver://127.0.0.1:1433;DatabaseName=TestServlet","sa","123456");
PreparedStatement ps = ct.prepareStatement("select * from users where username=? and passwd=?");
ps.setString(1,u);
ps.setString(2,p);
ResultSet rs = ps.executeQuery();
if(rs.next()){
//合法，转到欢迎页面
response.sendRedirect("wel.jsp?user="+u);
}else{
//不合法，转到登录页面
response.sendRedirect("login.jsp");
}
%>
</body>
</html>
欢迎界面代码：
<%@ page language="java" contentType="text/html; charset=gb2312" import="java.sql.*"
pageEncoding="gb2312"%>
<!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=gb2312">
<title>欢迎页面</title>
</head>
<body>
<center>
welcome,<%= request.getParameter("user") %><br>
<a href="login.jsp">返回重新登录</a>
<hr>
<%
//分页的功能
int pageSize = 3; //每页显示3条记录
int pageNow = 1; //首先显示第一页的内容
int pageCount = 0; //一共有多少页（通过计算获得）
int rowCount = 0; //一共有多少行记录（通过查表获得）
//动态的接收pageNow的值
String s_pageNow = request.getParameter("s_pageNow");
if(null != s_pageNow)
{
pageNow = Integer.parseInt(s_pageNow);
}
//到数据库中查询rowCount的值
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
Connection ct = DriverManager.getConnection("jdbc:sqlserver://127.0.0.1:1433;DatabaseName=TestServlet","sa","123456");
PreparedStatement ps = ct.prepareStatement("select count(*)from users");
ResultSet rs = ps.executeQuery();
if(rs.next())
{
rowCount = rs.getInt(1);
}
//计算pageCount的值
if(rowCount%pageSize == 0)
{
pageCount = rowCount/pageSize;
}else
{
pageCount = rowCount/pageSize + 1;
}
ps = ct.prepareStatement("select top "
+pageSize+" * from users where userID not in (select top "
+pageSize*(pageNow-1)+" userID from users)");
rs = ps.executeQuery();
//用表格显示用户的信息
%>
<table border="1">
<tr><td>用户ID</td><td>用户名</td><td>密码</td><td>邮箱</td><td>等级</td></tr>
<%
while(rs.next())
{
out.println("<tr>");
out.println("<td>"+rs.getInt(1)+"</td>");
out.println("<td>"+rs.getString(2)+"</td>");
out.println("<td>"+rs.getString(3)+"</td>");
out.println("<td>"+rs.getString(4)+"</td>");
out.println("<td>"+rs.getInt(5)+"</td>");
out.println("</tr>");
}
%>
</table>
<%
//显示超链接
if(1 != pageNow)
{
out.println("<a href=wel.jsp?s_pageNow=1>[首页]</a>");
out.println("<a href=wel.jsp?s_pageNow="+(pageNow-1)+">[上一页]</a>");
}
for(int i=1; i<=pageCount; ++i){
out.println("<a href=wel.jsp?s_pageNow="+i+">["+i+"]</a>");
}
if(pageCount != pageNow)
{
out.println("<a href=wel.jsp?s_pageNow=1>[下一页]</a>");
out.println("<a href=wel.jsp?s_pageNow="+(pageNow+1)+">[尾页]</a>");
}
%>
</center>
</body>
</html>