스프링 DB 접근 기술(1) - 순수 JDBC

DB 설정

MariaDB가 설치되어 있어서 이것으로 진행할 것이다.

 

create table member
(
    id bigint auto_increment,
    name varchar(255),
    primary key (id)
);

insert into member(name)
values ('spring');

auto_increment는 값을 세팅하지 않고 insert하면 db가 자동으로 값을 채워준다.

 

 

순수 JDBC

환경설정

build.gradle파일에 jdbc, db 관련 라이브러리를 추가해야 한다.

 

build.gradle

spring.datasource.url=jdbc:mariadb://localhost:3306
spring.datasource.driver-class-name=org.mariadb.jdbc.Driver
spring.datasource.username=root
spring.datasource.password=1234

spring.jpa.show-sql=true

 

생성

package hello.hellospring.repository;
import hello.hellospring.domain.Member;
import org.springframework.jdbc.datasource.DataSourceUtils;
import javax.sql.DataSource;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
public class JdbcMemberRepository implements MemberRepository {
    private final DataSource dataSource;
    public JdbcMemberRepository(DataSource dataSource) {
        this.dataSource = dataSource;
    }
    @Override
    public Member save(Member member) {
        String sql = "insert into member(name) values(?)";

        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;

        try {
            conn = getConnection();
            pstmt = conn.prepareStatement(sql,
                    Statement.RETURN_GENERATED_KEYS);

            pstmt.setString(1, member.getName());

            pstmt.executeUpdate();
            rs = pstmt.getGeneratedKeys();
            if (rs.next()) {
                member.setId(rs.getLong(1));
            } else {
                throw new SQLException("id 조회 실패");
            }
            return member;
        } catch (Exception e) {
            throw new IllegalStateException(e);
        } finally {
            close(conn, pstmt, rs);
        }
    }
    @Override
    public Optional<Member> findById(Long id) {
        String sql = "select * from member where id = ?";
        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        try {
            conn = getConnection();
            pstmt = conn.prepareStatement(sql);
            pstmt.setLong(1, id);
            rs = pstmt.executeQuery();
            if(rs.next()) {
                Member member = new Member();
                member.setId(rs.getLong("id"));
                member.setName(rs.getString("name"));
                return Optional.of(member);
            } else {
                return Optional.empty();
            }
        } catch (Exception e) {
            throw new IllegalStateException(e);
        } finally {
            close(conn, pstmt, rs);
        }
    }
    @Override
    public List<Member> findAll() {
        String sql = "select * from member";
        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        try {
            conn = getConnection();
            pstmt = conn.prepareStatement(sql);
            rs = pstmt.executeQuery();
            List<Member> members = new ArrayList<>();
            while(rs.next()) {
                Member member = new Member();
                member.setId(rs.getLong("id"));
                member.setName(rs.getString("name"));
                members.add(member);
            }
            return members;
        } catch (Exception e) {
            throw new IllegalStateException(e);
        } finally {
            close(conn, pstmt, rs);
        }
    }
    @Override
    public Optional<Member> findByName(String name) {
        String sql = "select * from member where name = ?";
        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        try {
            conn = getConnection();
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, name);
            rs = pstmt.executeQuery();
            if(rs.next()) {
                Member member = new Member();
                member.setId(rs.getLong("id"));
                member.setName(rs.getString("name"));
                return Optional.of(member);
            }
            return Optional.empty();
        } catch (Exception e) {
            throw new IllegalStateException(e);
        } finally {
            close(conn, pstmt, rs);
        }
    }
    private Connection getConnection() {
        return DataSourceUtils.getConnection(dataSource);
    }
    private void close(Connection conn, PreparedStatement pstmt, ResultSet rs)
    {
        try {
            if (rs != null) {
                rs.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        try {
            if (pstmt != null) {
                pstmt.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        try {
            if (conn != null) {
                close(conn);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    private void close(Connection conn) throws SQLException {
        DataSourceUtils.releaseConnection(conn, dataSource);
    }
}

 

 

DB를 사용하기 이전까지는 Memory를 사용했다. 이제 DB를 사용하니 Config를 변경해줘야 한다.

 

package hello.hellospring;

import hello.hellospring.repository.JdbcMemberRepository;
import hello.hellospring.repository.MemberRepository;
import hello.hellospring.repository.MemoryMemberRepository;
import hello.hellospring.service.MemberService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;

@Configuration
public class SpringConfig {

    DataSource dataSource;

    @Autowired
    public SpringConfig(DataSource dataSource) {
        this.dataSource = dataSource;
    }

    @Bean
    public MemberService memberService() {
        return new MemberService(memberRepository());
    }

    @Bean
    public MemberRepository memberRepository() {
//        return new MemoryMemberRepository();
        return new JdbcMemberRepository(dataSource);
    }
}

DataSource는 데이터베이스 커넥션을 획득할 때 사용하는 객체다. 스프링 부트는 데이터베이스 커넥션 정보를 바탕으로 DataSource를 생성하고 스프링 빈으로 만들어둔다. 그래서 DI를 받을 수 있다.

• 개방-폐쇄 원칙(OCP, Open-Closed Principle)
  • 확장에는 열려있고, 수정, 변경에는 닫혀있다.
• 스프링의 DI (Dependencies Injection)을 사용하면 기존 코드를 전혀 손대지 않고, 설정만으로 구현 클래스를 변경할 수 있다.