package auction.persistence;import org.hibernate.usertype.*;import auction.model.MonetaryAmount;import org.hibernate.*;import org.hibernate.engine.SessionImplementor;import java.util.*;import java.sql.*;import java.math.BigDecimal;/** * This type adds parameterizable currency conversion to the normal composite user type, * that is, you can set the target currency for the conversion (for the value saved and * loaded from the database) to any ISO code in your mapping, depending on the * situation/property to map. It maps a two-attribute component to two database columns. * <p> * Do not ask me how this currency conversion works. It doesn't work, it's not implemented. * The whole point of this class is not to show how you can convert money, but how * you can write a custom UserType. *  * @see MonetaryAmountSimpleUserType * @author Christian Bauer */public class MonetaryAmountType extends MonetaryAmountCompositeUserType implements ParameterizedType {	// The amount	private Currency convertTo;	public void setParameterValues(Properties parameters) {		this.convertTo = Currency.getInstance(parameters.getProperty("convertTo"));	}	public Object nullSafeGet(ResultSet resultSet,							  String[] names,							  SessionImplementor session,							  Object owner)			throws HibernateException, SQLException {		if (resultSet.wasNull()) return null;		BigDecimal value = resultSet.getBigDecimal( names[0] );        // When loading, take the currency from the database		Currency currency = Currency.getInstance(resultSet.getString( names[1] ) );        return new MonetaryAmount(value, currency);	}	public void nullSafeSet(PreparedStatement statement,							Object value,							int index,							SessionImplementor session)			throws HibernateException, SQLException {		if (value==null) {		    statement.setNull(index, Types.NUMERIC);		} else {		    MonetaryAmount amount = (MonetaryAmount) value;            // When saving, convert to target currency		    MonetaryAmount dbAmount = MonetaryAmount.convert(amount, convertTo);		    statement.setBigDecimal( index, dbAmount.getValue() );            statement.setString( index+1, convertTo.getCurrencyCode());		}	}	}