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narkisr on 03/12/08

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Last Edited at 03/12/08 12:40pm

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Java 5 Enum HIbernate mapping

/ Published in: Java

This is an example of how to map a Java 5 enum when using Hibernate ORM.

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import org.hibernate.HibernateException;
import org.hibernate.usertype.ParameterizedType;
import org.hibernate.usertype.UserType;
import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;
import java.util.Properties;

/** 
* This class implements the Type that will be used in the hbm file, notice that 
* the JavaEnumToString & StringToJavaEnum implementation isn't provided 
* (all they do is to convert Enum<->String in a consistent way, same goes for 
* StringUtils (replaceable with apache commons StringUtils).
*/
public class JavaEnumUserType implements UserType, ParameterizedType {

private static final int[] SQL_TYPE = new int[]{Types.VARCHAR};

private Class<? extends Enum> enumClass;

private static JavaEnumToString javaEnumToString = new JavaEnumToString();

private static StringToJavaEnum stringToJavaEnum = new StringToJavaEnum();

public void setParameterValues(Properties parameters) {
		String enumClassName = parameters.getProperty("enumClass");
		try {
			enumClass = Class.forName(enumClassName).asSubclass(Enum.class);
		} catch (ClassNotFoundException e) {
			throw new HibernateException("Class " + enumClassName + " not found ", e);
		}
	}

public Object assemble(Serializable cached, Object owner)
			throws HibernateException {
		return cached;
	}

public Object deepCopy(Object value) throws HibernateException {
		return value;
	}

public Serializable disassemble(Object value) throws HibernateException {
		return (Enum) value;
	}

public boolean equals(Object x, Object y) throws HibernateException {
		return x == y;
	}

public int hashCode(Object x) throws HibernateException {
		return x.hashCode();
	}

public boolean isMutable() {
		return false;
	}

public Object nullSafeGet(ResultSet rs, String[] names, Object owner) throws HibernateException, SQLException {
		String value = rs.getString(names[0]);
		if (rs.wasNull() || StringUtils.isNullOrEmpty(value)) {
			return null;
		}
		return stringToJavaEnum.doConvert(value.trim(), enumClass);
	}

public void nullSafeSet(PreparedStatement st, Object value, int index) throws HibernateException, SQLException {
		if (value == null) {
			st.setNull(index, Types.VARCHAR);
		} else {
			String stringValue = javaEnumToString.doConvert((Enum) value);
			st.setString(index, stringValue);
		}
	}

public Object replace(Object original, Object target, Object owner)
			throws HibernateException {
		return original;
	}

public Class returnedClass() {
		return enumClass;
	}

public int[] sqlTypes() {
		return SQL_TYPE;
	}

}

// For example the following bean:

public class DummyBean{
 
  private DummyEnum dummyProp;

public DummyEnum getDummyProp() {
    return dummyProp;
  }

public void setPageDescriptor(DummyEnum _dummyProp) {
    this.dummyProp = _dummyProp;
  }

}

// will be mapped in this fashion:

<hibernate-mapping>
  <class name="com.dummy.DummyBean" table="DUMMY_TABLE">

<property name="dummyProp" column="DUMMY_PROP">
    <type name="com.dummy.JavaEnumUserType">
      <param name="enumClass">com.dummy.DummyEnum</param>
    </type>
   </property>
</hibernate-mapping>

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