스프링 JdbcTemplate

JDBC API에서 반복 코드(result set connection 얻기 ...) 대부분 제거해줌.
but SQL은 직접 작성해야 함.

JdbcTemplateMemberRepository.java

public class JdbcTemplateMemberRepository implements MemberRepository {
    // alt+enter 로 import
    private final JdbcTemplate jdbcTemplate;

    public JdbcTemplateMemberRepository(DataSource dataSource) {
        jdbcTemplate = new JdbcTemplate(dataSource);
    }

    @Override
    public Member save(Member member) {
        SimpleJdbcInsert jdbcInsert = new SimpleJdbcInsert(jdbcTemplate);
        jdbcInsert.withTableName("member").usingGeneratedKeyColumns("id");
        Map<String, Object> parameters = new HashMap<>();
        parameters.put("name", member.getName());
        Number key = jdbcInsert.executeAndReturnKey(new
                MapSqlParameterSource(parameters));
        member.setId(key.longValue());
        return member;
    }

    @Override
    public Optional<Member> findById(Long id) {
        List<Member> result = jdbcTemplate.query("select * from member where id = ?", memberRowMapper(), id);
        return result.stream().findAny(); // result를 stream으로 바꿔서 optional로 반환
    }
    @Override
    public List<Member> findAll() {
        return jdbcTemplate.query("select * from member", memberRowMapper());
    }

    @Override
    public Optional<Member> findByName(String name) {
        List<Member> result = jdbcTemplate.query("select * from member where name = ?", memberRowMapper(), name);
        return result.stream().findAny();
    }

    private RowMapper<Member> memberRowMapper() {
//        return new RowMapper<Member>() {
//            @Override
//            public Member mapRow(ResultSet rs, int rowNum) throws SQLException {
//                Member member = new Member();
//                member.setId(rs.getLong("id"));
//                member.setName(rs.getString("name"));
//                return member;
//            }
//        }
        return (rs, rowNum) -> { // RowMapper에서 alt+enter: replace with lambda
            Member member = new Member();
            member.setId(rs.getLong("id"));
            member.setName(rs.getString("name"));
            return member;
        };
    }
}