案例:用户登录
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,day14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,恭喜您
登录失败跳转到FailServlet展示:登陆失败,用户名或密码错误
分析
开发步骤
1. 创建项目,导入html页面,配置文件,jar包
2. 创建数据库环境
CREATE DATABASE day14
USE day14;
CREATE TABLE USER(
id INT PRIMARY KEY AUTO_INCREMENT,
username VARCHAR(32) UNIQUE NOT NULL,
PASSWORD VARCHAR(32) NOT NULL
);
3. 创建包domain,创建类User
package 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 + '\'' +
'}';
}
}
4.JBDC工具类,使用Druid连接池
package util;
import com.alibaba.druid.pool.DruidDataSourceFactory;
import javax.sql.DataSource;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;
/**
* JBDC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 (Exception e) {
throw new RuntimeException(e);
}
}
/**
* 获取连接池对象
*/
public static DataSource getDateSource() {
return ds;
}
/**
* 获取连接Connection对象
*/
public static Connection getConnection() throws SQLException {
return ds.getConnection();
}
}
5. 创建包dao,创建类UserDao,提供login方法
package Dao;
import domain.User;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import util.JDBCUtils;
/**
* 操作数据库中User表的类
*/
public class UserDao {
//声明JDBCTemplate对象共用
private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDateSource());
/**
* 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.调用方法
User user = template.queryForObject(sql,
new BeanPropertyRowMapper<User>(User.class),
loginUser.getUsername(), loginUser.getPassword());
return user;
} catch (DataAccessException e) {
e.printStackTrace();//记录日志
return null;
}
}
}
6.编写Servlet.LoginServlet类
package web.Servlet;
import Dao.UserDao;
import 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 {
private String message;
public void init() {
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
//1.设置编码
request.setCharacterEncoding("utf-8");
//2.设置请求参数
String username = request.getParameter("username");
String password = request.getParameter("password");
//3.封装user对象
User loginUser = new User();
loginUser.setUsername(username);
loginUser.setPassword(password);
//4.调用UserDao的login对象
UserDao dao = new UserDao();
User user = dao.login(loginUser);
//5.判断user
if (user == null) {
//登陆失败
request.getRequestDispatcher("/failServlet").forward(request, response);
} else {
//登录成功
//存储数据
request.setAttribute("user", user);
//转发
request.getRequestDispatcher("/successServlet").forward(request, response);
}
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
this.doGet(request, response);
}
}
7. login.html中form表单中action路径的写法
- 虚拟目录+Servlet的资源路径
8. BeanUtils工具类,简化数据封装
- 用于封装JavaBean的
- JavaBean:标准的Java类
- 要求:
- 类必须被public修饰
- 必须提供空参的构造器
- 成员变量必须使用private修饰
- 提供公共setter和getter方法
- 功能:封装数据
- 要求:
- 概念:
- 成员变量
- 属性:setter和getter方法截取后的产物
- 例如:getUsername() —> Username —> username
- 方法
- populate(Object obj, Map map):将map集合的键值对信息,封装到对应的JavaBean对象中