Persisting an Enum with Hibernate

The following code is a template for easy Enum 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 EnumType<E extends Enum<E>> implements UserType {

 private static final int[] SQL_TYPES = {Types.VARCHAR};
 private Class<E> clazz = null;

 protected EnumType(Class<E> clazz) {
 this.clazz = clazz;
 }

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

 public Class<E> 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);
 }
}

Here is an example Enum:

public ExampleEnum {
 ENUM_A,
 ENUM_B;
}

Now we just need to create the following custom mapping type:

public class ExampleEnumType extends EnumType<ExampleEnum> {

public ExampleEnumType() {
 super(ExampleEnum.class);
 }
}

Finally, add it to your mapping file:

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

Or add it via Annotation:

@Entity
@TypeDef(name = "exampleEnumTypeDef", typeClass = ExampleEnumType.class)
public class Test {
 private ExampleEnum exampleEnum;
 [...]

@Type(type = "exampleEnumTypeDef")
@Column(name = "example")
public ExampleEnum getExample() {
 return exampleEnum;
 }

public void setExample(ExampleEnum exampleEnum) {
 this.exampleEnum = exampleEnum;
 }
}

I helps me very well and I hope you too.

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