커뮤니티에서 확인한대로 프로젝트를 닫고 buildgradle에서도 열어봤고 findById도 확인해 봤는데 계속 빨간 줄입니다,, 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); }}