JavaWeb实现用户登录【HTML+MySQL+JDBCTemplate+Servlet+Druid连接池】
JavaWeb实现用户登录【HTML+MySQL+JDBCTemplate+Servlet+Druid连接池】
一、用户登录案例需求：
- 编写login.html登录页面，username & password 两个输入框
- 使用Druid数据库连接池技术,操作mysql，数据库中user表
- 使用JdbcTemplate技术封装JDBC
- 登录成功跳转到SuccessServlet展示：登录成功！用户名,欢迎您
- 登录失败跳转到FailServlet展示：登录失败，用户名或密码错误
二、用户登录案例分析：
三、创建项目
- 创建JavaWeb项目，将druid.properties放入src文件中。druid.properties文件的相关内容如下：
driverClassName=com.mysql.cj.jdbc.Driver
url=jdbc:mysql:///db_student_manager_web?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=UTC&rewriteBatchedStatements=true
username=root
password=root
initialSize=5
maxActive=10
maxWait=3000
- 在web/WEB-INF下创建lib文件，将用到JDBCTemplate的相关jar包，全部导入lib文件中。对于想要了解其相关内容，可以点击右侧链接JDBCTemplate的相关知识
- jar包的相关目录如下：
- 将jar包Add as Librsry；然后导入html页面，login.html中的form表单的action路径的写法是：虚拟目录+Servlet的资源路径
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Titletitle>
head>
<body>
<form action="" 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>
四、 创建数据库的环境
- 创建USER表格
CREATE TABLE `user` (
`id` INT NOT NULL AUTO_INCREMENT,
`username` VARCHAR ( 32 ) NOT NULL,
`password` VARCHAR ( 32 ) NOT NULL,
PRIMARY KEY ( `id` ),
UNIQUE KEY `username` ( `username` )
) ENGINE = INNODB DEFAULT CHARSET = utf8;
- 在user表格里面添加数据，用于后面的登录操作
三、编写代码
- 创建cn.itcast.domain，创建类User
package cn.itcast.domain;
/**
* 用户的实体类
*/
public class User {
private int id;
private String username;
private String password;
public int getId() {
return id;
}
public void setId(int 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;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
", password='" + password + '\'' +
'}';
}
}
- 创建cn.itcast.dao，创建类UserDao，提供login方法
package cn.itcast.dao;
import cn.itcast.domain.User;
import cn.itcast.util.JDBCUtils;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
/**
* 操作数据库中User表的类
*/
public class UserDao {
//声明JDBCTemplate对象共用
protected JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());
/**
* 登录方法
* @param loginUser 只有用户名和密码
* @return user包含用户全部数据 , 没有查询到，返回null
*/
public User login(User loginUser){
try {
//1.编写sql
String sql = "select * from user where username = ? and password = ?";
//2.调用query方法
User user = template.queryForObject(sql,
new BeanPropertyRowMapper<User>(User.class),
loginUser.getUsername(), loginUser.getPassword());
return user;
}catch (DataAccessException e){
e.printStackTrace();
return null;
}
}
}
- 创建cn.itcast.util，创建JDBC工具类，使用Druid连接池
package cn.itcast.util;
import com.alibaba.druid.pool.DruidDataSourceFactory;
import javax.sql.DataSource;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;
/**
* JDBC工具类，使用Druid连接池
*/
public class JDBCUtils {
private static DataSource ds;
static {
try {
//1.加载配置文件
Properties pro = new Properties();
//使用ClassLoader加载配置文件，获取字节输入流
InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
pro.load(is);
//2.初始化连接池对象
ds = DruidDataSourceFactory.createDataSource(pro);
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
//获取连接池对象
public static DataSource getDataSource(){
return ds;
}
//获取连接Connection对象
public static Connection getConnection() throws SQLException {
return ds.getConnection();
}
}
- 创建cn.itcast.web.servlet，创建LoginServlet类
package cn.itcast.web.servlet;
import cn.itcast.dao.UserDao;
import cn.itcast.domain.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 {
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//1.设置编码
req.setCharacterEncoding("utf-8");
//2.获取请求参数
String username = req.getParameter("username");
String password = req.getParameter("password");
//3.封装user对象
User loginUser = new User();
loginUser.setUsername(username);
loginUser.setPassword(password);
//4.调用UserDao的login方法
UserDao dao = new UserDao();
User user = dao.login(loginUser);
//5.判断user
if (user == null){
//登陆失败
req.getRequestDispatcher("/FailServlet").forward(req,resp);
}else {
//登录成功
//存储数据
req.setAttribute("user",user);
//转发
req.getRequestDispatcher("/SuccessServlet").forward(req,resp);
}
}
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req, resp);
}
}
- 编写类FailServlet和类SuccessServlet的跳转页面。
- FailServlet类文件：
package cn.itcast.web.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 {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//设置页面编码
response.setContentType("text/html;charset=utf-8");
//输出
response.getWriter().write("登录失败，用户名或密码错误");
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
}
- SuccessSuServlet类文件：
package cn.itcast.web.servlet;
import cn.itcast.domain.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("/SuccessSuServlet")
public class SuccessServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
User user = (User) request.getAttribute("user");
if (user != null){
//设置编码
response.setContentType("text/html;charset=utf-8");
//输出
response.getWriter().write("登录成功！！"+user.getUsername()+",欢迎你");
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
}
五、登录效果演示
扩展：优化代码
截止到此，已经实现了通过使用JavaWeb来实现用户登录的功能，但是对于代码的上述的编写，还是有些欠缺的地方；在LoginServlet类文件中将username，password都封装成了对象，上述的页面也就只有两个参数想要进行数据封装；那么要是注册页面，需要很多的数据项需要封装的话，会造成代码冗余。
那么我们可以通过下面的方法将数据一次性全部获取，然后封装。
BeanUtils工具类，简化数据封装
- 将commons-beanutils-1.8.0.jar包放入web/WEB-INF/ilb文件中，然后 Add as Library。
- 重新编写LoginServlet类。
package cn.itcast.web.servlet;
import cn.itcast.dao.UserDao;
import cn.itcast.domain.User;
import org.apache.commons.beanutils.BeanUtils;
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.lang.reflect.InvocationTargetException;
import java.util.Map;
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//1.设置编码
req.setCharacterEncoding("utf-8");
//2.获取所有请求参数
Map<String, String[]> map = req.getParameterMap();
///3.创建User对象
User loginUser = new User();
//3.2使用BeanUtils封装
try {
BeanUtils.populate(loginUser,map);
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
//4.调用UserDao的login方法
UserDao dao = new UserDao();
User user = dao.login(loginUser);
//5.判断user
if (user == null){
//登陆失败
req.getRequestDispatcher("/FailServlet").forward(req,resp);
}else {
//登录成功
//存储数据
req.setAttribute("user",user);
//转发
req.getRequestDispatcher("/SuccessServlet").forward(req,resp);
}
}
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req, resp);
}
}
- BeanUtils工具类，用于JavaBean，封装数据。
方法：
- setProperty()
- getProperty()
- populate（Obgect obj，Map map）：将map集合的键值对信息，封装到对应的JavaBean集合中。