UserType for persisting an Enum with a VARCHAR column

UserType for persisting an Enum with a VARCHAR column

The following code is a 'template' to easy Enum (Java 1.5) mapping.

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

public class EnumUserType<E extends Enum<E>> implements UserType { 
    private Class<E> clazz = null; 
    protected EnumUserType(Class<E> c) { 
        this.clazz = c; 
    } 
 
    private static final int[] SQL_TYPES = {Types.VARCHAR}; 
    public int[] sqlTypes() { 
        return SQL_TYPES; 
    } 
 
    public Class returnedClass() { 
        return clazz; 
    } 
 
    public Object nullSafeGet(ResultSet resultSet, String[] names, Object owner) throws HibernateException, SQLException { 
        String name = resultSet.getString(names[0]); 
        E result = null; 
        if (!resultSet.wasNull()) { 
            result = Enum.valueOf(clazz, name); 
        } 
        return result; 
    } 
 
    public void nullSafeSet(PreparedStatement preparedStatement, Object value, int index) throws HibernateException, SQLException { 
        if (null == value) { 
            preparedStatement.setNull(index, Types.VARCHAR); 
        } else { 
            preparedStatement.setString(index, ((Enum)value).name()); 
        } 
    } 
 
    public Object deepCopy(Object value) throws HibernateException{ 
        return value; 
    } 
 
    public boolean isMutable() { 
        return false; 
    } 
 
    public Object assemble(Serializable cached, Object owner) throws HibernateException  
         return cached;
    } 

    public Serializable disassemble(Object value) throws HibernateException { 
        return (Serializable)value; 
    } 
 
    public Object replace(Object original, Object target, Object owner) throws HibernateException { 
        return original; 
    } 
    public int hashCode(Object x) throws HibernateException { 
        return x.hashCode(); 
    } 
    public boolean equals(Object x, Object y) throws HibernateException { 
        if (x == y) 
            return true; 
        if (null == x || null == y) 
            return false; 
        return x.equals(y); 
    } 
} 

Now, let's imagine you have the following Enum:

public enum MyEnum { 
    ENUM_A, 
    ENUM_B; 
}

Just create the following custom mapping type:

public class MyEnumUserType extends EnumUserType<MyEnum> { 
    public MyEnumUserType() {
        super(MyEnum.class);
    }
}

And finally, in your mapping file:

<hibernate-mapping>
[...]
  <property name="sample" type="mypackage.MyEnumUserType" not-null="true"/>
[...]

Vincent