[210224] 자바의 트랜잭션

con.setAutoCommit(false);

public void updateCoffeeSales(HashMap<String, Integer> salesForWeek) throws SQLException {
  String updateString = 
    "update COFFEES set SALES = ? where COF_NAME = ?";
  String updateStatement = 
    "update COFFEES set TOTAL = TOTAL + ? where COF_NAME = ?";

  try (PreparedStatement updateSales = con.PreparedStatement(updateString);
       PreparedStatement updateTotal = con.PreparedStatement(updateStatement))
  {
    con.setAutoCommit(false);  // 주목!
    for (Map.Entry<String, Integer> e : salesForWeek.entrySet()) {
      updateSales.setInt(1, e.getValue().intValue());
      updateSales.setString(2, e.getKey());
      updateSales.executeUpdate();  // 커밋은 되지 않는다.

      updateTotal.setInt(1, e.getValue().intValue());
      updateTotal.setString(2, e.getKey());
      updateTotal.executeUpdate();  // 커밋은 되지 않는다.

      con.commit();  // 여기서 커밋이 진행된다.
    }
  } catch (SQLException e) {
    JDBCtutorialUtilities.printSQLException(e);
    if (con != null) {
      try {
	System.err.print("Transaction is being rolled back");
	con.rollback();
      } catch (SQLException excep) {
	JDBCtutorialUtilities.printSQLException(excep);
      }
    }
  }
}

public void modifyPricesByPercentage(String coffeeName, float priceModifier, float maximumPrice) throws SQLException{
  String priceQuery = "SELECT COF_NAME, PRICE FROM COFFEES WHERE OF_NAME = ?";
  String updateQuery = "UPDATE COFFEES SET PRICE = ? WHERE COF_NAME = ?";

  try (PreparedStatement getPrice = con.PreparedStatement(priceQuery, ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
       PreparedStatement updatePrice = con.PreparedStatement(updateQuery)) 
  {
    Savepoint save1 = con.setSavePoint();  // save point!
    getPrice.setString(1, coffeeName);
    if (!getPrice.execute()) {
      System.out.println("Could not find entry for coffee name " + coffeeName); // 못찾음.
    } else {
      rs = getPrice.getResultSet();
      rs.first()
      float oldPrice = rs.getFloat("PRICE");
      float newPrice = oldPrice + (oldPrice * priceModifier);
      System.out.printf("Old price of %s is $%.2f%n", coffeeName, oldPrice);
      System.out.printf("New price of %s is $%.2f%n", coffeeName, newPrice);
      System.out.println("Performing update...");
      updatePrice.setFloat(1, newPrice);
      updatePrice.setString(2, coffeeName);
      updatePrice.executeUpdate();
      System.out.println("\nCOFFEES table after update:");
      CoffeesTable.viewTable(con);
      if (newPrice > maximumPrice) {
      System.out.printf("The new price, $%.2f, is greater " +
			"than the maximum price, $%.2f. " +
			"Rolling back the transaction...%n",
			newPrice, maximumPrice);
      con.rollback(save1);  // save point로 롤백한다.
      System.out.println("\nCOFFEES table after rollback:");
      CoffeesTable.viewTable(con);
    }
    con.commit();
    }
  }
}

Savepoint save1 = con.setSavepoint();
con.rollback(save1);

@Transactional(propagation=TransactionDefinition.NESTED, 
	       isolation=TransactionDefinition.ISOLATION_READ_UNCOMMITTED)

import java.sql.Connection;

// isolation=TransactionDefinition.ISOLATION_READ_UNCOMMITTED
connection.setTransactionIsolation(Connection.TRANSACTION_READ_UNCOMMITTED); 

// propagation=TransactionDefinition.NESTED
Savepoint savePoint = connection.setSavePoint();
...
connection.rollback(savePoint)

@Configuration
@EnableTransactionManagement
public class MySpringConfig {
  @Bean
  public PlatformTransactionManager txManager() {
    // 요렇게 트랜잭션매니저를 지정할 수 있다?!
    return yourTxManager; // more on that later
  }
}

public class UserService {
  public Long registerUser(User user) {
    Connection connection = dataSource.getConnection(); // (1)
    try (connection) {
      connection.setAutoCommit(false); // (1)

      // execute some SQL that e.g.
      // inserts the user into the db and retrieves the autogenerated id
      // userDao.save(user); <(2)

      connection.commit(); // (1)
    } catch (SQLException e) {
      connection.rollback(); // (1)
    }
  }
}

public class UserService {
  @Autowired
  private SessionFactory sessionFactory; // (1) 하이버네이트 객체, 모든 쿼리의 엔트리 포인트

  public void registerUser(User user) {

    Session session = sessionFactory.openSession(); // (2) DB 커넥션

    // lets open up a transaction. remember setAutocommit(false)!
    session.beginTransaction();

    // save == insert our objects
    session.save(user);

    // and commit it
    session.getTransaction().commit();

    // close the session == our jdbc connection
    session.close();
  }
}

@Service
public class UserService {
  @Autowired
  private SessionFactory sessionFactory; // 위에서 본 녀석

  @Transactional
  public void registerUser(User user) {
    sessionFactory.getCurrentSession().save(user); // 위랑은 다르게 이거 하나로 끝낸다고?
  }
}