[Java] 124. JDBC에서의 예외 처리

[Java] 124. JDBC에서의 예외 처리

 

1. SQLException 다루기

-- DML DCL DDL 
-- 컬럼 추가하는 쿼리를 만들어보자.

drop table users;
create table users(
	id int auto_increment primary key,
    username varchar(100) not null unique,
    password varchar(100) not null
);

desc users;

alter table users add column email varchar(100) null;

-- 이메일에다가 unique 제약을 추가해보자.
alter table users add constraint unique_email unique(email);

insert into users(username,password,email)
values('홍길동','asd123','a@naver.com'),
('이순신','asd123','b@naver.com'),
('박태환','asd123','c@naver.com')

 

 

package ver4;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Scanner;
import java.util.logging.Level;
import java.util.logging.Logger;

public class LogInExample {
	
	// 개발 테스트를 위한 로깅 처리 및 로그
	private static final Logger LOGGER = Logger.getLogger(LogInExample.class.getName());
	
	public static void main(String[] args) {
		// DataSource를 활용한 Connection 객체를 사용하자.
		
		try {
			// HikariCP 가 담김
			Connection conn = DBConnectionManager.getConnection();
			// username, id, password를 받아서 확인해야 한다.
			
			Scanner scanner=new Scanner(System.in);
			System.out.print(" username을 입력하세요 : ");
			String username=scanner.nextLine();
			System.out.println(" 비밀번호를 입력하세요 : ");
			String password=scanner.nextLine();
			
			if(authenticateUser(conn,username,password)) {
				System.out.println("로그인 성공");
			} else {
				System.out.println("로그인 실패");
			}
			
			// select*from users where username='' and password='';
			
		} catch (SQLException e) {
			LOGGER.log(Level.INFO,"MySQL 연결 오류");
			e.printStackTrace();
		}
		
	} // end of main
	
	private static boolean authenticateUser(Connection conn, String username, String password) {
		String query="select*from users where username=? and password=? ";
		boolean result=false;
		
		try {
			PreparedStatement pstmt = conn.prepareStatement(query);
			pstmt.setString(1, username);
			pstmt.setString(2, password);
			ResultSet rs = pstmt.executeQuery();
			
			result=rs.next();
			
		} catch (Exception e) {
			e.printStackTrace();
		}
	
		return result;
	}
 
} // end of class

package ver4;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Scanner;
import java.util.logging.Level;
import java.util.logging.Logger;

public class LogInExample {
	
	// 개발 테스트를 위한 로깅 처리 및 로그
	private static final Logger LOGGER = Logger.getLogger(LogInExample.class.getName());
	
	public static void main(String[] args) {
		// DataSource를 활용한 Connection 객체를 사용하자.
		
		try {
			// HikariCP 가 담김
			Connection conn = DBConnectionManager.getConnection();
			// username, id, password를 받아서 확인해야 한다.
			
			Scanner scanner=new Scanner(System.in);
			System.out.print(" username을 입력하세요 : ");
			String username=scanner.nextLine();
			System.out.println(" 비밀번호를 입력하세요 : ");
			String password=scanner.nextLine();
			
			if(authenticateUser(conn,username,password)) {
				System.out.println("로그인 성공");
			} else {
				System.out.println("로그인 실패");
			}
			
			// select*from users where username='' and password='';
			
		} catch (SQLException e) {
			LOGGER.log(Level.INFO,"MySQL 연결 오류");
			e.printStackTrace();
		}
		
	} // end of main
	
	private static boolean authenticateUser(Connection conn, String username, String password) {
		String query="select*from users where username=? and password=? ";
		boolean result=false;
		
		try {
			PreparedStatement pstmt = conn.prepareStatement(query);
			pstmt.setString(1, username);
			pstmt.setString(2, password);
			ResultSet rs = pstmt.executeQuery();
			
			result=rs.next();
			
		} catch (Exception e) {
			e.printStackTrace();
		}
	
		return result;
	}
 
} // end of class