GenerationType, JPA提供的四种标准用法为TABLE,SEQUENCE,IDENTITY,AUTO.

package com.ak47.cms.cms.entity

import java.util.*
import javax.persistence.*

@Entity
@Table(indexes = arrayOf(Index(name = "idx_category", columnList = "category")))
class Tree {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    var id: Long = 0

    var parentId: Long = 0

    @Column(length = 200)
    var name = ""

    @Column(length = 100)
    var category = ""

    var gmtCreated = Date()
    var gmtModified = Date()
    var isDeleted = 0
    @Version
    var version = 0
}

/*
 * Copyright (c) 2008, 2009, 2011 Oracle, Inc. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.  The Eclipse Public License is available
 * at http://www.eclipse.org/legal/epl-v10.html and the Eclipse Distribution License
 * is available at http://www.eclipse.org/org/documents/edl-v10.php.
 */
package javax.persistence;

/**
 * Defines the types of primary key generation strategies.
 *
 * @see GeneratedValue
 *
 * @since Java Persistence 1.0
 */
public enum GenerationType {

    /**
     * Indicates that the persistence provider must assign
     * primary keys for the entity using an underlying
     * database table to ensure uniqueness.
     */
    TABLE,

    /**
     * Indicates that the persistence provider must assign
     * primary keys for the entity using a database sequence.
     */
    SEQUENCE,

    /**
     * Indicates that the persistence provider must assign
     * primary keys for the entity using a database identity column.
     */
    IDENTITY,

    /**
     * Indicates that the persistence provider should pick an
     * appropriate strategy for the particular database. The
     * <code>AUTO</code> generation strategy may expect a database
     * resource to exist, or it may attempt to create one. A vendor
     * may provide documentation on how to create such resources
     * in the event that it does not support schema generation
     * or cannot create the schema resource at runtime.
     */
    AUTO
}