MyBatis | MyBatis란 | Hello World

<?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="sample_id">
    <environment id="sample_id">
      <transactionManager type="JDBC"/>
      <dataSource type="POOLED">
        <property name="driver" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost/test"/>
        <property name="username" value="test"/>
        <property name="password" value="test"/>
      </dataSource>
    </environment>
  </environments>
  <mappers>
    <mapper resource="sample_mapper.xml"/>
  </mappers>
</configuration>

<?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="sample.mybatis">
  <select id="selectTest" resultType="map">
    select * from test_table
  </select>
</mapper>

package sample.mybatis;

import java.io.InputStream;
import java.util.List;
import java.util.Map;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class Main {

    public static void main(String[] args) throws Exception {
        // 루트가 되는 설정 파일을 로드한다.
        try (InputStream in = Main.class.getResourceAsStream("/mybatis-config.xml")) {
            //  설정 파일을 바탕으로 SqlSessionFactory를 생성한다.
            SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);

            // SqlSessionFactory에서 SqlSession을 생성한다.
            try (SqlSession session = factory.openSession()) {
                // SqlSession을 사용하여 SQL을 실행한다.
                List<Map<String, Object>> result = session.selectList("sample.mybatis.selectTest");

                result.forEach(row -> {
                    System.out.println("---------------");
                    row.forEach((columnName, value) -> {
                        System.out.printf("columnName=%s, value=%s%n", columnName, value);
                    });
                });
            }
        }
    }
}