EDIT

package eu.etaxonomy.cdm.hibernate;

import java.io.Serializable;

import java.math.BigDecimal;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Types;

import org.hibernate.HibernateException;

import org.hibernate.engine.spi.SessionImplementor;

import org.hibernate.type.BigDecimalType;

import org.hibernate.type.StandardBasicTypes;

import org.hibernate.usertype.UserType;

/**

 * Hibernate {@link UserType} for BigDecimal with correct handling for scale.

 * Correct means that a BigDecimal with scale 2 will be stored and reloaded

 * with scale 2 even if the defined scale in the database has a higher scale defined.

 *

 * E.g. "1.32" is persisted as exactly this BigDecimal even if scale of the column is

 * defined with scale = 4. The default {@link BigDecimalType} stores and reloads it

 * as 1.3200 which is a difference when handling e.g. measurement values as it looses the

 * information about the exactness of the data.<BR><BR>

 *

 * Usage example with annotations (with type already declared in according package-info.java):<BR>

 *

 * <BR>@Columns(columns={@Column(name="xxx", precision = 18, scale = 9), @Column(name="xxx_scale")})

 * <BR>@Type(type="bigDecimalUserType")

 * <BR><BR>

 *

 * This class has been originally copied and adapted from

 * https://bitbucket.org/ratkins/bigdecimalusertype/src/default/<BR><BR>

 */

public class BigDecimalUserType implements UserType {

	private static final int[] SQL_TYPES = new int[] {

	        Types.NUMERIC, //for some reason Types.Decimal does not exist at least in MySQL Dialect

	        Types.INTEGER};

	@Override

	public Object assemble(Serializable arg0, Object arg1) throws HibernateException {

		return deepCopy(arg0);

	}

	@Override

	public Object deepCopy(Object arg0) throws HibernateException {

		return arg0;

	}

	@Override

	public Serializable disassemble(Object arg0) throws HibernateException {

		return (Serializable) arg0;

	}

	@Override

	public boolean equals(Object arg0, Object arg1) throws HibernateException {

		return arg0.equals(arg1);

	}

	@Override

	public int hashCode(Object arg0) throws HibernateException {

		return arg0.hashCode();

	}

	@Override

	public boolean isMutable() {

		return false;

	}

	@Override

	public Object nullSafeGet(ResultSet rs, String[] names, SessionImplementor session, Object owner) throws HibernateException, SQLException {

		BigDecimal bigDecimal = (BigDecimal) StandardBasicTypes.BIG_DECIMAL.nullSafeGet(rs, names, session, owner);

		if (bigDecimal == null) {

			return null;

		}

		return bigDecimal.setScale(rs.getInt(names[1]), BigDecimal.ROUND_HALF_UP);

	}

	@Override

	public void nullSafeSet(PreparedStatement st, Object value, int index, SessionImplementor session) throws HibernateException, SQLException {

		if (value == null) {

			StandardBasicTypes.BIG_DECIMAL.nullSafeSet(st, null, index, session);

			StandardBasicTypes.INTEGER.nullSafeSet(st, null, index+1, session);

		} else {

			BigDecimal bdec = (BigDecimal)value;

			StandardBasicTypes.BIG_DECIMAL.nullSafeSet(st, bdec, index, session);

			StandardBasicTypes.INTEGER.nullSafeSet(st, bdec.scale(), index + 1, session);

		}

	}

	@Override

	public Object replace(Object arg0, Object arg1, Object arg2) throws HibernateException {

		return arg0;

	}

	@Override

	public Class<?> returnedClass() {

		return BigDecimal.class;

	}

	@Override

	public int[] sqlTypes() {

		return SQL_TYPES;

	}

}