JDBC実習

ファイル構造

Role.java

package kr.or.connect.jdbcexam.dto;

public class Role {
	private Integer roleId;
	private String description;
	
	public Role(Integer roleId, String description) {
		super();
		this.roleId=roleId;
		this.description=description;
	}
	
	public Integer getRoleId() {
		return roleId;
	}
	public void setRoleId(Integer roleId) {
		this.roleId = roleId;
	}
	public String getDescription() {
		return description;
	}
	public void setDescription(String description) {
		this.description = description;
	}
	
	@Override
	public String toString() {
		return "Role [roleId=" + roleId + ", description=" + description + "]";
	}
}

RoleDao.java

package kr.or.connect.jdbcexam.dao;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import kr.or.connect.jdbcexam.dto.Role;

public class RoleDao {
	private static String dburl = "jdbc:mysql://localhost:3306/connectdb";
	private static String dbUser = "connectuser";
	private static String dbpasswd = "connect123!@#";
	
	public Role getRole(Integer roleId) {
		Role role = null;
		Connection conn = null;
		PreparedStatement ps = null;
		ResultSet rs = null;
		
		try {
			Class.forName("com.mysql.jdbc.Driver");
			conn = DriverManager.getConnection(dburl, dbUser, dbpasswd);
			// preparedStatement가 가지고 있는 물음표에 대한 값을 지정 가능
			String sql = "SELECT description, role_id FROM role WHERE role_id = ?";
			ps = conn.prepareStatement(sql); // sql문을 실행시키도록 함
			ps.setInt(1, roleId);//1번째 물음표에 roleId 변수를 적용
			rs = ps.executeQuery();
			
			if(rs.next()) {
				String description = rs.getString(1); // 첫번째 column의 값 가져옴
				int id = rs.getInt(2); //column이 가진 값 가져옴
				role = new Role(id, description);
			}
		}catch (Exception e) {
			e.printStackTrace();
		}finally {
			if(rs != null) { // rs가 null일 때는 수행되지 않도록 함
				try {
					rs.close();
				} catch (SQLException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			if(ps != null) { // ps가 null일 때는 수행되지 않도록 함
				try {
					ps.close();
				} catch (SQLException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			if(conn != null) { // conn가 null일 때는 수행되지 않도록 함
				try {
					conn.close();
				} catch (SQLException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			
		}
		
		return role;
	}
}

JDBCExam1.java

package kr.or.connect.jdbcexam;

import kr.or.connect.jdbcexam.dao.RoleDao;
import kr.or.connect.jdbcexam.dto.Role;

public class JDBCExam1 {
	public static void main(String[] args) {
		RoleDao dao = new RoleDao();
		Role role = dao.getRole(100); #role_id 가 100인 레코드를 가져옴
		System.out.println(role);
	}
}

結果