This article is the homework completed after class following the Maven project cityFileFK01 above. It may have to be rewritten in class, for reference only.
Article Directory
1. The database design is as follows:
2. The file catalog is classified as follows:
3.DBUtil class
package util;
/*
连接数据的类
*/
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;
public class DBUtil {
private static String username;
private static String password;
private static String url;
private static String driver;
static {
try {
InputStream in = DBUtil.class.getClassLoader().getResourceAsStream("db.properties");
// FileInputStream in=new FileInputStream("db.properties");
System.out.println("in:" + in);
Properties p = new Properties();
p.load(in);
username = p.getProperty("db.username");
password = p.getProperty("db.password");
url = p.getProperty("db.url");
driver = p.getProperty("db.driver");
System.out.println(username);
System.out.println(password);
System.out.println(url);
System.out.println(driver);
} catch (IOException e) {
e.printStackTrace();
}
}
//封装一个连接方法
public static Connection getConn() {
Connection conn = null;
try {
//加载驱动
Class.forName(driver);
conn = DriverManager.getConnection(url, username ,password);
System.out.println("...........................");
System.out.println(conn);
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}
Db.properties under 4.resources
db.username=root
db.password=123456
db.url=jdbc:mysql://localhost:3306/citylifefk?characterEncoding=utf8
db.driver=com.mysql.jdbc.Driver
5. UsersCDao class under dao
package dao;
import util.DBUtil;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class UsersCDao {
private String username;
private String password;
public UsersCDao(String username, String password) {
this.username = username;
this.password = password;
}
public Integer selectStudent() throws SQLException {
//获得连接
Connection connection= DBUtil.getConn();
//编辑数据库语句
String sql="select role from tb_admin_user where uname=\""+username+"\"and pwd=\""+password+"\"";
//建立statement对象和resuleset结果对象
Statement statement=null;
ResultSet resultSet=null;
try {
int role=-1;
int count=0;
statement=connection.createStatement();
resultSet=statement.executeQuery(sql);
//用ResultSet的next方法判断是否有下一个
while (resultSet.next()){
//将相关的属性值引出来 并且存入到student对象中
role=resultSet.getInt("role");
count++;
}
if (count!=1){
return -1;
}
return role;
} catch (SQLException throwables) {
throwables.printStackTrace();
}finally {
resultSet.close();
statement.close();
connection.close();
}
return -1;
}
}
6. LoginServlet class under the controller
package controller;
import dao.UsersCDao;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.SQLException;
/*登录*/
@WebServlet(urlPatterns = "/toLogin")
public class LoginServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//当前servlet默认编码为ISO8859-1不支持中文，应先设置中文编码格式
req.setCharacterEncoding("utf-8");
//接受参数（接收用户填写的信息）
String username = req.getParameter("username");
String password = req.getParameter("password");
//根据用户名和密码查询当前用户信息是否存在，在dao里写
//定义一个变量存储结果
Integer result = null;
UsersCDao usersCDao=new UsersCDao(username,password);
try {
//将查询结果返回给result
result=usersCDao.selectStudent();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
//根据查询结果值不同进入不同页面，在这里只是原理演示，如果result等于0或1或2则分别为超级用户、普通用户、管理员用户
if (result == 0){
//使用重定向的方法 跳转到对应的页面
resp.sendRedirect("index.jsp");
}else if (result==1){
resp.sendRedirect("index.jsp");
}else if (result==2){
resp.sendRedirect("index.jsp");
}else {
//如果查询结果不为0、1、2，则表明在用户名错误或者密码错误，返回错误提示界面
resp.sendRedirect("error.jsp");
}
}
}
7.login.jsp
The front-end login.jsp page submits the user name and password
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@page isELIgnored="false" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<base href="<%=request.getContextPath()%>/"/>
<title>用户登录</title>
<link type="text/css" rel="stylesheet" href="/css/style.css;">
</head>
<body bgcolor="#E7ECEF">
<center>
<form action="/toLogin" method="post">
<table border="0" cellspacing="0" cellpadding="0" style="margin-top:130px">
<tr><td><img src="/images/logon_top.gif"></td></tr>
<tr height="180">
<td background="/images/logon_middle.gif" align="center" valign="top">
<table border="0" width="90%" cellspacing="0" cellpadding="0">
<tr height="50"><td colspan="2"></td></tr>
<tr height="30">
<td align="right" width="40%">用户名： </td>
<td style="text-indent:5px">
<input type="text" name="username" size="30px" value="" id="log_Login_action_user_userName"/>
<span>${
error}</span>
</td>
</tr>
<tr height="30">
<td align="right">密 码： </td>
<td style="text-indent:5px"><input type="password" name="password" size="30px" id="log_Login_action_user_userPassword"/></td>
</tr>
<tr height="60">
<td></td>
<td>
<input type="submit" id="" value="登录"/>
<input type="reset" value="重置"/>
<a id="log_Login_action_" href="/view/indextemp.jsp">[返回首页]</a>
</td>
</tr>
</table>
</td>
</tr>
<tr><td><img src="/images/logon_end.gif"></td></tr>
</table>
</form>
</center>
</body>
</html>
8.index.jsp
The user name and password are correct to enter the index.jsp page
<html>
<body>
<h2>Hello World!</h2>
</body>
</html>
9.error.jsp
The user name and password are wrong to enter the page error.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body >
<img src="/images/1.png">
</body>
</html>
10. Running results:
Run tomcat and enter http://localhost:8066/login.
Effect:
If the user name and password are entered correctly, enter http://localhost:8066/index.jsp
If the user name and password are entered incorrectly, enter http://localhost:8066/ error.jsp
