JDBC

yenn·2021년 8월 4일

Backend JDBC Java Spring Springboot

Spring

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순수 jdbc

환경 설정

라이브러리 추가

build.gradle

implementation 'org.springframework.boot:spring-boot-starter-jdbc'
runtimeOnly 'com.h2database:h2'

Spring Boot database 연결 설정 추가

application.properties

spring.datasource.url=jdbc:h2:tcp://localhost/~/test
spring.datasource.driver-class-name=org.h2.Driver
spring.datasource.username=sa

공백 주의

JDBC 회원 리포지토리 구현

JDBC API 로 구현하는것은 너무 오래전 이야기이기 때문에 참고만 하자

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) {

				// 상수로 빼는 것이 더 좋음
        String sql = "insert into member(name) values(?)";
        Connection conn = null;
        PreparedStatement pstmt = null;
				// 결과 값 
        ResultSet rs = null;

        try {
						// 1. connection 가져오기
            conn = getConnection();
						// 2. prepareStatement를 통해서 sql 넣고,
						// 3. RETURN_GENARATED_KEYS : db에 insert 하여 id 값 생성
            pstmt = conn.prepareStatement(sql,
                    Statement.RETURN_GENERATED_KEYS);
						// 4. 첫번째 '?' 변수에 값 넣음
            pstmt.setString(1, member.getName());
						// 5. 실제 db쿼리에 업데이트 됨
						// executeUpdate : 생성할 때
            pstmt.executeUpdate();
						// 6. 결과로 generateKey를 반환 해줌 (PK값) 
            rs = pstmt.getGeneratedKeys();
						
						// 만약에 result 값이 있다면
            if (rs.next()) {
								// 값을 가져옴 
                member.setId(rs.getLong(1));
            } else {
                throw new SQLException("id 조회 실패");
            }
            return member;
        } catch (Exception e) {
            throw new IllegalStateException(e);
        } finally {
						// 사용 후에는 무조건 close를 해줘야 함
            close(conn, pstmt, rs);
        }
    }

    @Override
    public Optional<Member> findById(Long id) {
				// 쿼리 생성
        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);
						// executeQuery() : 조회할 때 
            rs = pstmt.executeQuery();

            if(rs.next()) {
								// 값이 있으면 member 객체 생성하고 반환
                Member member = new Member();
                member.setId(rs.getLong("id"));
                member.setName(rs.getString("name"));
                return Optional.of(member);
            } else {
								// 없을 경우 empty return
                return Optional.empty();
            }
        } 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);
        }
    }

    @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);
        }
    }

    private Connection getConnection() {
        return DataSourceUtils.getConnection(dataSource);
    }

    private void close(Connection conn, PreparedStatement pstmt, ResultSet rs) {
        // 생성된 역순으로 close 해줘야 함
				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();
        }
        try {
            if (conn != null) {
                close(conn);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    private void close(Connection conn) throws SQLException {
        DataSourceUtils.releaseConnection(conn, dataSource);
    }
}

spring framework 사용하여 데이터베이스에 접근하고 close할 때에는 DataSourceUtils를 통해 접근해야 함

스프링 설정 변경

SpringConfig

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 {

    private DataSource dataSource;

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

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

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