所需技术:Servlet + html + Mysql + JDBCTemplate + Druid + tomcat
<html lang="en">
<head>
<meta charset="UTF-8">
<title>首页title>
head>
<body>
<form action="/05_14_logindemo/loginServlet" method="post">
用户名: <input type="text" name="username"><br>
密码: <input type="password" name="password"><br>
<input type="submit" value="登录">
form>
body>
html>
CREATE DATABASE java_123;
USE java_123;
CREATE TABLE USER(
id INT PRIMARY KEY AUTO_INCREMENT,
username VARCHAR(32) UNIQUE NOT NULL,
PASSWORD VARCHAR(32) NOT NULL,
insert_time TIMESTAMP
);
package com.huike.javabean;
import java.io.Serializable;
import java.util.Date;
/**
* 在实体类中的基本数据类型最好定义成对应的包装类
*/
public class User implements Serializable {
//最好用包装类:template.queryForObject如果找不到会
private Integer id;
private String username;
private String password;
private Date insertTime;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public Date getInsertTime() {
return insertTime;
}
public void setInsertTime(Date insertTime) {
this.insertTime = insertTime;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
", password='" + password + '\'' +
", insertTime=" + insertTime +
'}';
}
}
package com.huike.utils;
import com.alibaba.druid.pool.DruidDataSourceFactory;
import javax.sql.DataSource;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
/**
* JDBC工具类 使用Druid数据库连接池
*/
public class JDBCUtils {
private static DataSource ds;
//在静态代码块中获取ds对象
static {
try {
//加载配置文件
Properties properties = new Properties();
InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
properties.load(is);
//获取数据库连接池对象 工厂类获取对象
ds = DruidDataSourceFactory.createDataSource(properties);
//获取连接:getConnection()
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 获取连接池对象
*/
public static DataSource getDs(){
return ds;
}
/**
* 获取Connection对象
*/
public static Connection getConnection() throws SQLException {
return ds.getConnection();
}
/**
* 释放资源(两个参数) 通过方法重载实现功能的全面性
*/
public static void close(Statement stmt, Connection conn) {
close(null, stmt, conn);
}
/**
* 释放资源(三个参数) 通过方法重载实现功能的全面性
*/
public static void close(ResultSet rs, Statement stmt, Connection conn) {
if (rs != null) {
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (stmt != null) {
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
package com.huike.dao;
import com.huike.javabean.User;
import com.huike.utils.JDBCUtils;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
/**
* 操作数据库user表的类
*/
public class UserDao {
//1.获取template对象
private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDs());
/**
* 登录方法 代码编写完成后 最好去测试下
* @param loginUser:传递给我的user对象 只有用户名和密码属性有值
* @return 返回一个user对象 如果数据库中有对应的用户名和密码则user不为null 如果没有 user为null
*/
public User login(User loginUser){
User user = null;
try {
String sql = "select * from user where username = ? and password = ?";
//2.调用对应的方法
user = template.queryForObject(sql,
new BeanPropertyRowMapper<User>(User.class),
loginUser.getUsername(), loginUser.getPassword());
} catch (DataAccessException e) {
// e.printStackTrace();
return null;
//queryForObject方法如果查询不到对应的值会出异常 为了让它查询不到返回null 我们进行手动try catch
}
return user;
}
}
判断数据库是否与后台连接成功(测试)
package com.huike.test;
import com.huike.dao.UserDao;
import com.huike.javabean.User;
import org.junit.Test;
public class UserDaoTest {
@Test
public void testLogin(){
User loginUser = new User();
// loginUser.setUsername("瓜皮");
// loginUser.setPassword("guapi");
loginUser.setUsername("黄瓜皮");
loginUser.setPassword("huanggua");
UserDao userDao = new UserDao();
User user = userDao.login(loginUser);
System.out.println(user);
}
}
package com.huike.servlet;
import com.huike.dao.UserDao;
import com.huike.javabean.User;
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;
@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1.设置编码格式
request.setCharacterEncoding("UTF-8");
//2.获取请求的参数
String username = request.getParameter("username");
String password = request.getParameter("password");
//3.将请求的参数封装到user对象中
User loginUser = new User();
loginUser.setUsername(username);
loginUser.setPassword(password);
//4.调用 UserDao 中的 login方法
UserDao userDao = new UserDao();
User user = userDao.login(loginUser);
//5.判断是否登录成功
String path = null;
if (user == null){
//登录失败 请求转发
path = "/failServlet";
}else{
//登录成功 存储数据 转发
request.setAttribute("user",user);
path = "/successServlet";
}
//转到对应的servlet
request.getRequestDispatcher(path).forward(request,response);
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
}
user为null 登录失败 FailServlet
package com.huike.servlet;
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;
@WebServlet("/failServlet")
public class FailServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
response.getWriter().write("登录失败!您的用户名或密码输错啦...
");
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
}
user不为null 登录成功 SuccessServlet
package com.huike.servlet;
import com.huike.javabean.User;
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;
@WebServlet("/successServlet")
public class SuccessServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 获取request中存储的user对象
User user = (User) request.getAttribute("user");
if (user != null){
response.setContentType("text/html;charset=utf-8");
response.getWriter().write("登录成功!"
+user.getUsername()+",欢迎您");
}
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
}
实现