2020.12.21ログ

54523 ワード

JDBC テキストリンク

今日のダイジェスト

트랜잭션を勉強しました.学んだ過程をずっと以下のように詠んでいる.

ビジネスアルゴリズム

を先に記述する

1. 계좌주의 이메일이 맞는지 체킹 
2. 보내는 사람의 잔액이 이체금액보다 많은지 체킹 
3. 보내는 사람의 잔액을 - 
4. 받는 사람의 잔액을 + 
5. 이체 기록 
6. 계좌 내용을 보여줌 
7. 연결객체를 닫기 
8. 이체하기 메소드 for User

Info.JAva合成

Sql.JAva合成

transaction.sql JDBC/JAVAアカウント

を読み込みます.

Transfer.Javaを作成し、implements eclipseで自動的に作成します(下図参照)

TrsansferImpl.Javaにおけるビジネスアルゴリズムの編成

を実現する

TsUser.JAva合成

Info.java

package day09.bank;

public class Info {
	public static final String url = "jdbc:oracle:thin:@127.0.0.1:1521:JAVA";
	public static final String usr = "JDBC";
	public static final String pwd = "JAVA";
}

Sql.java

package day09.bank;

public class Sql {
	public static final String sql1 = "select * from ACC where EMAIL=?";
	public static final String sql2 = "select BALANCE from ACC where EMAIL=?";
	public static final String sql3 = 
	"update ACC set BALANCE=((select BALANCE from ACC where EMAIL=?)-?), UDATE=SYSDATE where EMAIL=?";
	public static final String sql4 = 
	"update ACC set BALANCE=((select BALANCE from ACC where EMAIL=?)+?), UDATE=SYSDATE where EMAIL=?";
	public static final String sql5 =
	"insert into TRAN_LOG values(TRAN_LOG_SEQ.nextval, ?,?,?, CURRENT_TIMESTAMP)";
	public static final String sql6 =
    "select * from ACC where EMAIL=? or EMAIL=?";
}

transaction.sql

-- (1) ACC create 
drop table ACC;
create table ACC(
    EMAIL varchar2(20) constraint ACC_PK primary key, 
    NAME varchar2(10),   
    BALANCE number,
    UDATE date, 
    CDATE date
); 
insert into ACC values('[email protected]', '홍길동', 1000000, null, SYSDATE);
insert into ACC values('[email protected]', '이순신', 1000000, null, SYSDATE);
commit;
--select TABLE_NAME, CONSTRAINT_NAME, CONSTRAINT_TYPE from user_constraints where TABLE_NAME='ACC';

-- (2) TRAN_LOG create 
drop table TRAN_LOG;
drop sequence TRAN_LOG_SEQ; 
create table TRAN_LOG(
    SEQ number constraint TRAN_LOG_PK primary key, 
    SENDER varchar2(20), 
    RECEIVER varchar2(20), 
    AMOUNT number, 
    RDATE timestamp 
);
create sequence TRAN_LOG_SEQ increment by 1 start with 1 nocache;
--select TABLE_NAME, CONSTRAINT_NAME, CONSTRAINT_TYPE from user_constraints where TABLE_NAME='TRAN_LOG';

select * from ACC;
select * from TRAN_LOG;

--10000원 
--update ACC set BALANCE=((select BALANCE from ACC where EMAIL='[email protected]')-10000) where EMAIL='[email protected]'
--update ACC set BALANCE=((select BALANCE from ACC where EMAIL='[email protected]')+10000) where EMAIL='[email protected]'
--insert into TRAN_LOG values(TRAN_LOG_SEQ.nextval, '[email protected]', '[email protected]', 10000, CURRENT_TIMESTAMP);

Transfer.java

package day09.bank;

import java.sql.SQLException;

public interface Transfer {
	boolean isMember(String email); //S
	boolean checkBalance(String sender, long amount); //S
	boolean minus(String sender, long amount); //U
	boolean plus(String receiver, long amount); //U
	boolean log(String sender, String receiver, long amount); //I
	void showResult(String sender, String receiver); //S
	void closeAll();
	
	boolean transfer(String sender, String receiver, long amount) throws SQLException; // for User
}

TransferImpl.java

package day09.bank;

import java.sql.*;

public class TransferImpl implements Transfer {
	private Connection con;
	private PreparedStatement pstmt1, pstmt2, pstmt3, pstmt4, pstmt5, pstmt6;
	public TransferImpl() {
		try {
			 
			Class.forName("oracle.jdbc.driver.OracleDriver");
			System.out.println("1. 드라이버 로딩 성공");
			con = DriverManager.getConnection(Info.url, Info.usr, Info.pwd);
			con.setAutoCommit(false);
			System.out.println("2. 커넥션 생성 성공");
			pstmt1 = con.prepareStatement(Sql.sql1);
			pstmt2 = con.prepareStatement(Sql.sql2);
			pstmt3 = con.prepareStatement(Sql.sql3);
			pstmt4 = con.prepareStatement(Sql.sql4);
			pstmt5 = con.prepareStatement(Sql.sql5);
			pstmt6 = con.prepareStatement(Sql.sql6);
			System.out.println("3. 스테이트먼트 생성 성공");
		}catch(ClassNotFoundException cnfe) {
			System.out.println("TransferImpl() cnfe: "+ cnfe);
		}catch(SQLException se) {
			System.out.println("TransferImpl() se: "+ se);
		}
	}
	@Override
	public boolean isMember(String email) {
		ResultSet rs = null;
		try {
			pstmt1.setString(1, email);
			rs = pstmt1.executeQuery();
			if(rs.next()) return true;
			else return false;
		}catch(SQLException se) {
			return false;
		}finally {
			try {
				rs.close();
			}catch(SQLException se){}
		}
	}

	@Override
	public boolean checkBalance(String sender, long amount) {
		ResultSet rs = null;
		try {
			pstmt2.setString(1, sender);
			rs = pstmt2.executeQuery();
			if(rs.next()) {
				Long balance = rs.getLong(1);
				if((balance-amount) >= 0) {
					return true;
				}else {
					return false;
				}
			}else {
				return false;
			}
		}catch(SQLException se) {
			return false;
		}finally {
			try {
				rs.close();
			}catch(SQLException se){}
		}
	}

	@Override
	public boolean minus(String sender, long amount) {
		try {
			pstmt3.setString(1, sender);
			pstmt3.setLong(2, amount);
			pstmt3.setString(3, sender);
			int i = pstmt3.executeUpdate();
			if(i>0) return true;
			else return false;
		}catch(SQLException se) {
			return false;
		}
	}

	@Override
	public boolean plus(String receiver, long amount) {
		try {
			pstmt4.setString(1, receiver);
			pstmt4.setLong(2, amount);
			pstmt4.setString(3, receiver);
			int i = pstmt4.executeUpdate();
			if(i>0) return true;
			else return false;
		}catch(SQLException se) {
			return false;
		}
	}

	@Override
	public boolean log(String sender, String receiver, long amount) {
		try {
			pstmt5.setString(1, sender);
			pstmt5.setString(2, receiver);
			pstmt5.setLong(3, amount);
			int i = pstmt5.executeUpdate();
			if(i>0) return true;
			else return false;
		}catch(SQLException se) {
			return false;
		}
	}

	@Override
	public void showResult(String sender, String receiver) {
		ResultSet rs = null;
		try {
			pstmt6.setString(1, sender);
			pstmt6.setString(2, receiver);
			rs = pstmt6.executeQuery();
			System.out.println("EMAIL \t NAME \t BALANCE \t UDATE \t CDATE");
			while(rs.next()) {
				String email = rs.getString(1);
				String name = rs.getString(2);
				long balance = rs.getLong(3);
				Date udate = rs.getDate(4);
				Date cdate = rs.getDate(5);
				System.out.println(email+"\t"+name+"\t"+balance+"\t"+udate+"\t"+cdate);
			}
		}catch(SQLException se) {
		}finally {
			try {
				rs.close();
			}catch(SQLException se) {}
		}
	}

	@Override
	public void closeAll() {
		try {
			if(pstmt6 != null) pstmt6.close();
			if(pstmt5 != null) pstmt5.close();
			if(pstmt4 != null) pstmt4.close();
			if(pstmt3 != null) pstmt3.close();
			if(pstmt2 != null) pstmt2.close();
			if(pstmt1 != null) pstmt1.close();
			if(con != null) con.close();
		}catch(SQLException se) {}
	}

	@Override
	public boolean transfer(String sender, String receiver, long amount) throws SQLException {
		boolean flag1 = isMember(sender);
		boolean flag2 = isMember(receiver);
		if(flag1 & flag2) {
			System.out.println("(1) 2명 모두 계좌주 확인됨");
			if(checkBalance(sender, amount)) {
				System.out.println("(2) sender의 잔액이 충분함");
				if(minus(sender, amount)) {
					System.out.println("(3) 보내는 사람의 잔액을 - 성공");
					if(plus(receiver, amount)) {
						System.out.println("(4) 받는 사람의 잔액을 + 성공");
						if(log(sender, receiver, amount)) {
							System.out.println("(5) 이체 기록 성공");
							con.commit();
							return true;
						}else {
							System.out.println("(5) 이체 기록 실패");
							con.rollback();
							return false;
						}
					}else {
						System.out.println("(4) 받는 사람의 잔액을 + 실패");
						con.rollback();
						return false;
					}
				}else {
					System.out.println("(3) 보내는 사람의 잔액을 - 실패");
					con.rollback();
					return false;
				}
			}else {
				System.out.println("(2) sender의 잔액이 부족함");
				return false;
			}
		}else {
			System.out.println("(1) 2명중 적어도 1명이상은 계좌주가 아님");
			return false;
		}
	}
}

Reference

この問題について(2020.12.21ログ), 我々は、より多くの情報をここで見つけました https://velog.io/@peachy/study-046

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