案例：用户登录
-
用户登录案例需求：
- 编写login.html登录页，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技术方正JDBC
- 登录成功后跳转到SuccessServlet展示：登录成功！用户名，欢迎您
- 登录失败后跳转到FailServlet展示：登录失败，用户名或密码错误
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实现练习代码：
1.将第三方jar包进行依赖，因为我使用的开源版IDEA所以不会创建javaee，web项目，然后我手动按照javaee动态项目结构一个文件夹一个文件夹的创建出来了；
但在依赖过程中遇到的一个问题就是：import jakarta.servlet.http.HttpServlet;的HttpServlet类需要导报导入tomcat的包，我看网上说都是将HttpServlet单独的jar包导入，但是我这里是直接将tomcat的lib目录下的jar全部导入进来；
导入后编写代码：
login.html
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<form action="/loginDemo/loginServlet" method="post">
<input name="username">
<input name="password">
<input type="submit" value="提交">
</form>
</body>
</html>
user.java
package cn.itcast.domain;
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 + '\'' +
'}';
}
}
userDao.java
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对象公用
private JdbcTemplate template=new JdbcTemplate(JDBCUtils.getDataSource());
/**
* 登录方法
* @param loginUser，只有用户名和密
* @return user包含用户全部数据
*/
public User login(User loginUser){
try {
String sql = "select * from accoun where username= ? and password = ?";
User user = template.queryForObject(sql,
new BeanPropertyRowMapper<User>(User.class),
loginUser.getUsername(), loginUser.getPassword());
return user;
}catch(DataAccessException e){
e.printStackTrace();
return null; }
}
}
JDBCUtils.java
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Durid连接池
*/
public class JDBCUtils {
private static DataSource ds;
static{
//1.加载配置文件
Properties pro=new Properties();
InputStream resourceAsStream = JDBCUtils.class.getClassLoader().getResourceAsStream("dd.properties");
try {
pro.load(resourceAsStream);
ds = DruidDataSourceFactory.createDataSource(pro);
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
//初始化连接池对象
}
public static DataSource getDataSource(){
return ds;
}
public static Connection getConnection() throws SQLException{
return ds.getConnection();
}
}
FailServlet.java
package cn.itcast.web.servlet;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet("/failServlet")
public class FailServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
resp.setHeader("Content-type", "text/html;charset=UTF-8");
resp.setCharacterEncoding("UTF-8");
resp.getWriter().write("用户登录失败");
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req,resp);
}
}
SuccessServlet.java
package cn.itcast.web.servlet;
import cn.itcast.domain.User;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet("/successServlet")
public class SuccessServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
User user = (User) req.getAttribute("user");
resp.setHeader("Content-type", "text/html;charset=UTF-8");
resp.setCharacterEncoding("UTF-8");
resp.getWriter().write("登录成功欢迎您"+user.getUsername());
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req,resp);
}
}
loginServlet.java
package cn.itcast.web.servlet;
import cn.itcast.dao.UserDao;
import cn.itcast.domain.User;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import java.io.IOException;
@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");
String username = req.getParameter("username");
String password = req.getParameter("password");
User user = new User();
user.setUsername(username);
user.setPassword(password);
UserDao userDao=new UserDao();
User login = userDao.login(user);
if(login==null){
req.getRequestDispatcher("/failServlet").forward(req,resp);
}else{
req.setAttribute("user",user);
req.getRequestDispatcher("/successServlet").forward(req,resp);
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req,resp);
}
}
dd.properties
driverClassName=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/db1
username=root
password=502900
initalSize=2
maxActive=2
maxWait=3000
BeanUtils工具类，简化封装
用于封装javaBean的
1.标准的java类
1. 类必须被public修饰
2. 必须是提供供餐的构造器
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
- 概念：
- 成员变量：
- 属性：setter和getter方法截取后的产物
- 例如：getUsername方法（）--> Username --> username成员变量
- 方法
- setProperty（）设置属性值
- getProperty （）获取属性值
- populate（Object obj，map map）将map集合的键值对信息，封装到对应的bean类中
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