Transaction Management in Spring - Spring Enterprise Recipes: A Problem Solution Approach - page 161

public class JdbcBookShop implements BookShop {
private DataSource dataSource;
public void setDataSource(DataSource dataSource) {
this.dataSource = dataSource;
}
public void purchase(String isbn, String username) {
Connection conn = null;
try {
conn = dataSource.getConnection();
PreparedStatement stmt1 = conn.prepareStatement(
" SELECT PRICE FROM BOOK WHERE ISBN = ? " );
stmt1.setString(1, isbn);
ResultSet rs = stmt1.executeQuery();
rs.next();
int price = rs.getInt( " PRICE " );
stmt1.close();
PreparedStatement stmt2 = conn.prepareStatement(
" UPDATE BOOK_STOCK SET STOCK = STOCK - 1 " +
" WHERE ISBN = ? " );
stmt2.setString(1, isbn);
stmt2.executeUpdate();
stmt2.close();
PreparedStatement stmt3 = conn.prepareStatement(
" UPDATE ACCOUNT SET BALANCE = BALANCE - ? " +
" WHERE USERNAME = ? " );
stmt3.setInt(1, price);
stmt3.setString(2, username);
stmt3.executeUpdate();
stmt3.close();
} catch (SQLException e) {
throw new RuntimeException(e);
} finally {
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {}
}
}
}
}