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,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
分析:
开发步骤
1、创建项目,导入html页面,配置文件,jar包
创建项目:
导入html页面:
login.html
:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>用户登陆页面</title>
</head>
<body>
<form action="/UserLogin/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>
导入配置文件:
druid.properties
:
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql:///day14
username=root
password=123456
initialSize=5
maxActive=10
maxWait=3000
导入jar包:
导入下面的 jar 包,jar 包下载地址:https://pan.baidu.com/s/1el-pd0UDqD29vsUhAwu8kQ
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
);
INSERT INTO USER VALUES(null,"zhangsan","123456");
INSERT INTO USER VALUES(null,"lisi","1234");
3、创建包 cn.ys.entity
,创建类 User
package cn.ys.entity;
/**
* 用户实体类
*/
public class User {
private Integer id;
private String username;
private String password;
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;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
", password='" + password + '\'' +
'}';
}
}
4、创建包 cn.ys.util
,编写工具类 JDBCUtils
package cn.ys.util;
import com.alibaba.druid.pool.DruidDataSourceFactory;
import javax.sql.DataSource;
import java.io.IOException;
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 连接池
*/
public class JDBCUtils {
//1.定义成员变量 DataSource
private static DataSource ds ;
static{
try {
//1.加载配置文件
Properties pro = new Properties();
pro.load(JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties"));
//2.获取DataSource
ds = DruidDataSourceFactory.createDataSource(pro);
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 获取连接
*/
public static Connection getConnection() throws SQLException {
return ds.getConnection();
}
/**
* 释放资源
*/
public static void close(Statement stmt,Connection conn){
close(null,stmt,conn);
}
public static void close(ResultSet rs , Statement stmt, Connection conn){
if(rs != null){
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(stmt != null){
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(conn != null){
try {
conn.close();//归还连接
} catch (SQLException e) {
e.printStackTrace();
}
}
}
/**
* 获取连接池方法
*/
public static DataSource getDataSource(){
return ds;
}
}
5、创建包 cn.itcast.dao
,创建类 UserDao
,提供 login 方法
package cn.ys.dao;
import cn.ys.entity.User;
import cn.ys.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
private 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(); // 记录日志
return null;
}
}
}
测试 UserDao 是否能链接数据库
package cn.ys.test;
import cn.ys.dao.UserDao;
import cn.ys.entity.User;
import org.junit.Test;
public class UserDaoTest {
@Test
public void testUserDao(){
User loginUser = new User();
loginUser.setUsername("zhangsan");
loginUser.setPassword("123456");
UserDao userDao = new UserDao();
User user = userDao.login(loginUser);
System.out.println(user);
}
}
C:\Java\jdk1.8.0_181\bin\java.exe ...
信息: {dataSource-1} inited
User{id=1, username='zhangsan', password='123456'}
Process finished with exit code 0
6、创建包 cn.ys.web.servlet
,创建类 LoginServlet
package cn.ys.web.servlet;
import cn.ys.dao.UserDao;
import cn.ys.entity.User;
import javax.jws.WebService;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
*
*/
@WebService(name = "/loginServlet")
public class LoginServlet extends HttpServlet {
@Override
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){
//登录失败
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);
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req,resp);
}
}
7、编写 FailServlet
和 SuccessServlet
类
package cn.ys.web.servlet;
import cn.ys.entity.User;
import javax.jws.WebService;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebService(name = "/successServlet")
public class SuccessServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//获取request域中共享的user对象
User user = (User) req.getAttribute("user");
if(user != null){
//给页面写一句话
//设置编码
resp.setContentType("text/html;charset=utf-8");
//输出
resp.getWriter().write("登录成功!"+user.getUsername()+",欢迎您");
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req,resp);
}
}
package cn.ys.web.servlet;
import cn.ys.dao.UserDao;
import cn.ys.entity.User;
import javax.jws.WebService;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebService(name = "/failServlet")
public class FailServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//给页面写一句话
//设置编码
resp.setContentType("text/html;charset=utf-8");
//输出
resp.getWriter().write("登录失败,用户名或密码错误");
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req,resp);
}
}
补充
login.html 中 form 表单的 action 路径的写法
- 虚拟目录+Servlet的资源路径
BeanUtils 工具类,简化数据封装
1、导包:commons-beanutils-1.8.0.jar
下载地址:https://pan.baidu.com/s/1-qI8HRuhG4MdMifd1vNFGw
2、修改LoginServlet
:
package cn.ys.web.servlet;
import cn.ys.dao.UserDao;
import cn.ys.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 {
@Override
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);*/
//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){
//登录失败
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);
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req,resp);
}
}
BeanUtils 说明:
BeanUtils:用于封装 JavaBean 的。
什么是 JavaBean:标准的Java类
- 要求:
1. 类必须被public
修饰
2. 必须提供空参的构造器
3. 成员变量必须使用private
修饰
4. 提供公共setter
和getter
方法 - 功能:封装数据
例子:上面的 User 类,就是 JavaBean。
-
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:
- setProperty()
- getProperty()
- 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