Java 5 Enums Persistence with Hibernate

Added by eboz, last edited by eboz on Jun 05, 2007 17:43 Labels:  jpa, hibernate, enums Add Labels   Enter labels to add to this page: Tip: Looking for a label? Just start typing.

package org.appfuse.tutorial.model;

@Entity
@Table(name="t_person")
public class Person extends BaseObject {

   // Enumerations ---------------------------
     public enum Sex{

      MALE(1),
      FEMALE(2);

      private int value;

      Sex(int value) {
          this.value = value;
      }

      // the identifierMethod
      public int toInt() {
        return value;
      }

       // the valueOfMethod
       public  static Sex fromInt(int value) {    
           switch(value) {
               case 1: return MALE;
               case 2: return FEMALE;
               default:
                       return UNKNOW;
           }
      }
     
      public String toString() {
        switch(this) {
          case MALE:
              return "Male";
          case FEMALE:
              return "Female";
        }
      }
    }

    // Attributes ---------------------------

    @Id
    @Column(name= "person_id")
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;


    @Column(name="person_firstname", length = 50, nullable = false)
    private String firstName;


    @Column(name="person_lastname", length = 50, nullable = false)
    private String lastName;

   
    @Column(name= "person_sex", columnDefinition="integer", nullable = true)
    @Type(
        type = "org.appfuse.tutorial.commons.hibernate.GenericEnumUserType",
        parameters = {
                @Parameter(
                    name  = "enumClass",                      
                    value = "org.appfuse.tutorial.model.Person$Sex"),
                @Parameter(
                    name  = "identifierMethod",
                    value = "toInt"),
                @Parameter(
                    name  = "valueOfMethod",
                    value = "fromInt")
                }
    )
    private Sex sex;


    /*
     * Getters and Setters ...
     */
}

package org.appfuse.tutorial.commons.hibernate;

import java.io.Serializable;
import java.lang.reflect.Method;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;

import org.hibernate.HibernateException;
import org.hibernate.type.NullableType;
import org.hibernate.type.TypeFactory;
import org.hibernate.usertype.ParameterizedType;
import org.hibernate.usertype.UserType;


public class GenericEnumUserType implements UserType, ParameterizedType {
    private static final String DEFAULT_IDENTIFIER_METHOD_NAME = "name";
    private static final String DEFAULT_VALUE_OF_METHOD_NAME = "valueOf";

    private Class<? extends Enum> enumClass;
    private Class<?> identifierType;
    private Method identifierMethod;
    private Method valueOfMethod;
    private NullableType type;
    private int[] sqlTypes;

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

        String identifierMethodName = parameters.getProperty("identifierMethod", DEFAULT_IDENTIFIER_METHOD_NAME);

        try {
            identifierMethod = enumClass.getMethod(identifierMethodName, new Class[0]);
            identifierType = identifierMethod.getReturnType();
        } catch (Exception e) {
            throw new HibernateException("Failed to obtain identifier method", e);
        }

        type = (NullableType) TypeFactory.basic(identifierType.getName());

        if (type == null)
            throw new HibernateException("Unsupported identifier type " + identifierType.getName());

        sqlTypes = new int[] { type.sqlType() };

        String valueOfMethodName = parameters.getProperty("valueOfMethod", DEFAULT_VALUE_OF_METHOD_NAME);

        try {
            valueOfMethod = enumClass.getMethod(valueOfMethodName, new Class[] { identifierType });
        } catch (Exception e) {
            throw new HibernateException("Failed to obtain valueOf method", e);
        }
    }

    public Class returnedClass() {
        return enumClass;
    }

    public Object nullSafeGet(ResultSet rs, String[] names, Object owner) throws HibernateException, SQLException {  
        Object identifier = type.get(rs, names[0]);
        if (identifier == null) {
            return null;
        }
        
        try {
            return valueOfMethod.invoke(enumClass, new Object[] { identifier });
        } catch (Exception e) {
            throw new HibernateException("Exception while invoking valueOf method '" + valueOfMethod.getName() + "' of " +
                    "enumeration class '" + enumClass + "'", e);
        }
    }

    public void nullSafeSet(PreparedStatement st, Object value, int index) throws HibernateException, SQLException {
        try {
            if (value == null) {
                st.setNull(index, type.sqlType());
            } else {
                Object identifier = identifierMethod.invoke(value, new Object[0]);
                type.set(st, identifier, index);
            }
        } catch (Exception e) {
            throw new HibernateException("Exception while invoking identifierMethod '" + identifierMethod.getName() + "' of " +
                    "enumeration class '" + enumClass + "'", e);
        }
    }

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

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