JSP实现简单登录

<%@ page language="java" import="java.util.*"pageEncoding="ISO-8859-1"%>
<%@ page import="java.sql.*"%>
<%!
public static final String DBDRIVER = "com.mysql.jdbc.Driver" ;
public static final String userName ="root";   //登录的用户名
public static final String userPasswd = "jwzhangjie";  //登录mysql密码
public static final String dbName = "test";  //数据库名
public static final String tableName="tuser"; //表名
public static final String DBURL ="jdbc:mysql://localhost:3306/"+dbName+"?user="+userName+"&password="+userPasswd;
%>

<%
Connection conn = null ;
PreparedStatement pstmt = null ;
ResultSet rs = null ;
boolean flag = false ; // 表示登陆成功或失败的标记
%>

<%
String userid = request.getParameter("userid") ; // 接收表单参数
String password = request.getParameter("password") ; // 接收表单参数
try{
Class.forName(DBDRIVER) ;
conn = DriverManager.getConnection(DBURL) ;
String sql = "SELECT userid,password FROM tuser WHEREuserid=? AND password=?" ;
pstmt = conn.prepareStatement(sql) ;
pstmt.setString(1,userid) ;
pstmt.setString(2,password) ;
rs = pstmt.executeQuery() ;
while(rs.next()){
// 如果有内容，则此处执行，表示查询出来，合法用户
flag = true ;
}
}catch(Exception e){
}finally{
try{
conn.close() ; // 连接一关闭，所有的操作都将关闭
}catch(Exception e){}
}
%>
<%
if(flag){ // 登陆成功，应该跳转到success.jsp
%>
<jsp:forward page="success.jsp"/>
<%
}else{  // 登陆失败，跳转到failure.jsp
%>

<%
}
%>