Mybatis框架之工厂模式(Factory Pattern)

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
    PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
    "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mydatabase"/>
                <property name="username" value="root"/>
                <property name="password" value="password"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/example/mapper/UserMapper.xml"/>
    </mappers>
</configuration>

package com.example.mapper;

import com.example.model.User;
import java.util.List;

public interface UserMapper {
    List<User> getAllUsers();
    User getUserById(int id);
}

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
    PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
    "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.example.mapper.UserMapper">
    <select id="getAllUsers" resultType="com.example.model.User">
        SELECT * FROM users;
    </select>
    <select id="getUserById" parameterType="int" resultType="com.example.model.User">
        SELECT * FROM users WHERE id = #{id};
    </select>
</mapper>

import java.io.InputStream;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import com.example.mapper.UserMapper;
import com.example.model.User;
import java.util.List;

public class MyBatisExample {
    public static void main(String[] args) {
        String resource = "mybatis-config.xml";
        try (InputStream inputStream = Resources.getResourceAsStream(resource)) {
            // 1. 创建 SqlSessionFactory
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            
            // 2. 从工厂获取 SqlSession
            try (SqlSession session = sqlSessionFactory.openSession()) {
                // 3. 获取 Mapper 接口的实现
                UserMapper userMapper = session.getMapper(UserMapper.class);
                
                // 4. 调用方法执行 SQL
                List<User> users = userMapper.getAllUsers();
                users.forEach(user -> System.out.println(user.getName()));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}