一.程序实现思路
1.首先我们要在数据库中建立一个表
2.我们要写四个jsp文件：
(1)登录表单页面。
(2)检测页面。
(3)登录成功页面
(4)登录失败页面。
二.具体实现过程：
1.首先在mysql中建立一个表且插入一组数据：
mysql> use jdbc;
Database changed
mysql> create table user(
-> userid varchar(30) primary key,
-> name varchar(30) not null,
-> password varchar(32) not null);
Query OK, 0 rows affected (0.23 sec)
mysql> insert into user(userid,name,password)
-> values
-> (01,'yanjiad',1314520);
Query OK, 1 row affected (0.10 sec)
mysql> select * from user;
+--------+---------+----------+
| userid | name | password |
+--------+---------+----------+
| 1 | yanjiad | 1314520 |
+--------+---------+----------+
1 row in set (0.00 sec)
2.在Tomcat 文件夹中的lib目录下添加MySQL驱动包：
保证服务器能访问到数据库
3.四个页面的编写：
（1）登录页面 ：JaveWeb01.jsp
<%@ 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>登录页面</title>
</head>
<body>
<center>
<h1>登录操作</h1>
<hr>
<form action="login_check.jsp" method="post">
<table border="1">
<tr>
<td colspan="2">用户登录</td>
</tr>
<tr>
<td>登录ID：</td>
<td><input tepy="text" name="id"></td>
</tr>
<tr>
<td>登录密码：</td>
<td><input tepy="password" name="password"></td>
</tr>
<tr>
<td colspan="2">
<input type="submit" value="登录">
<input type="reset" value="重置">
</td>
</tr>
(2)检测页面：login_check.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@page import="java.sql.*" %>
<!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>Insert title here</title>
</head>
<body>
<%!
public static final String dbdriver="com.mysql.cj.jdbc.Driver";
public static final String dburl="jdbc:mysql://localhost:3306/jdbc?&useSSL=false&serverTimezone=UTC";
public static final String dbuser="root";
public static final String dbpass="root";
%>
<%
Connection conn=null;
PreparedStatement pstmt=null;
ResultSet rs=null;
boolean flag=false;
String name=null;
%>
<%
try{
Class.forName(dbdriver);
conn=DriverManager.getConnection(dburl,dbuser,dbpass);
String sql = "select name from user where userid=?and password=?";
pstmt=conn.prepareStatement(sql);
pstmt.setString(1,request.getParameter("id"));
pstmt.setString(2,request.getParameter("password"));
rs=pstmt.executeQuery();
if(rs.next()){
name=rs.getString(1);
flag=true;
}
}catch(Exception e){
System.out.println(e);
}
finally{
try{
rs.close();
pstmt.close();
conn.close();
}catch(Exception e){}
}
%>
<%
if(flag){
%>
<jsp:forward page="login_success.jsp">
<jsp:param value="<%=name %>" name="uname"/>
</jsp:forward>
<%
}else{
%>
<jsp:forward page="login_failure.jsp"/>
<%} %>
</body>
</html>
(3).成功页面：login_success.jsp
<%@ 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>Insert title here</title>
</head>
<body>
<center>
<h1>登录操作</h1>
<h2>登录成功</h2>
<h3>欢迎</h3>
</center>
</body>
</html>
(4)失败页面：login_failure.jsp
<%@ 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>Insert title here</title>
</head>
<body>
<center>
<h1>登录操作</h1>
<h2>登录失败，请重新登录<a href="JaveWeb01.jsp">登录</a></h2>
</center>
</body>
</html>
结果：
