http://shiwj1010.iteye.com/blog/385405
http://www.iteye.com/topic/95822
http://www.iteye.com/topic/76359
http://java.chinaitlab.com/Hibernate/763968.html
基于按annotation的hibernate主键生成策略之一
http://hi.baidu.com/babala_234/blog/item/8aae7445e30e933686947359.html
基于按annotation的hibernate主键生成策略之二
http://hi.baidu.com/babala_234/blog/item/84b25809c6e5b12d6a60fb5a.html
http://hi.baidu.com/%E7%F9%BB%C3%CE%E7%D2%B9/blog/item/4b24412c78bf093d359bf779.html
id生成策略:TABLE SEQUENCE ASSIGN UUID AUTO
@Id
@TableGenerator(
name="ID_GENERATOR",
table="ID_GEN",
pkColumnName = "GEN_NAME",
pkColumnValue = "NBR_PK",
valueColumnName = "GEN_VALUE",
initialValue = 1,
allocationSize = 1
)
@GeneratedValue(strategy=GenerationType.TABLE, generator="ID_GENERATOR")
@Column(name="NBR", length=10)
private Long nbr=0L;
JPA 会执行这样的语句:
update ID_GEN set GEN_VALUE = GEN_VALUE + 1 where GEN_NAME = ‘ NBR_PK’
通过这个sql语句就会明白注解里面各个属性的含义。
对于ID_GEN 表,不需要创建相应的Java entity
这种方式有个好处就是数据库的可移植
package org.app.dict.model;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.PrimaryKeyJoinColumn;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
import javax.persistence.UniqueConstraint;
import org.hibernate.annotations.GenericGenerator;
import org.hibernate.annotations.Index;
import com.ria.model.BaseVo;
@Entity
//表名+唯一约束限制[如果 表名与实体类名不一致就需要声明]
@Table(name="T_SYS_dict",uniqueConstraints = {@UniqueConstraint(columnNames = {"dict_name"}) })
@org.hibernate.annotations.Table(appliesTo = "T_SYS_dict",comment="字典表")
public class T_SYS_dict extends BaseVo {
private static final long serialVersionUID = 1L;
@Column(name="AD_Client_ID")
private int AD_Client_ID;
@Column(name="AD_Org_ID")
private int AD_Org_ID;
@Column(name="IsActive")
boolean IsActive = true;
@Temporal(TemporalType.TIMESTAMP)
@Column(name="Created")
private java.util.Date Created;
@Column(name="CreatedBy")
private int CreatedBy;
@Temporal(TemporalType.TIMESTAMP)
@Column(name="Updated")
private java.util.Date Updated;
@Column(name="UpdatedBy")
private int UpdatedBy;
/**
@Id
@GeneratedValue(generator = "system-uuid")
@GenericGenerator(name = "system-uuid", strategy = "uuid") //hibernate的uuid机制,生成32为字符串
--or--
@GeneratedValue(generator = "c-assigned")
@GenericGenerator(name = "c-assigned", strategy = "assigned") //hibernate的自定义机制
--or--
@GeneratedValue(strategy = GenerationType.AUTO,generator="test_sequence")
@SequenceGenerator(name = "test_sequence",sequenceName="TEST_SEQ")//采用 db sequence
--or--
@GeneratedValue(generator="myForeignGenerator")
@org.hibernate.annotations.GenericGenerator(
name="myForeigngenerator",
strategy="foreign",
parameters=@Parameter(name="property",value="User")
)
*/
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Index(name="T_SYS_INDEXS",columnNames={"T_SYS_dict_id"}) //加索引
@Column(name="T_SYS_dict_id",unique=true)
private long T_SYS_dict_id;
@Index(name="T_SYS_INDEXS",columnNames={"dict_name"}) //加索引
@Column(name = "dict_name", updatable = true, nullable = false, length = 36)
private String dict_name;
@Column(name = "remark", updatable = true, nullable = true, length = 255)
private String remark;
@Column(name="parent_id")
private long parent_id;
@Column(name="dict_order",length=3)
private int dict_order;
}
@TemporalType.(DATE,TIME,TIMESTAMP) 分别Map java.sql.(Date, Time, Timestamp).
@Lob 注解属性将被持久化为 Blog 或 Clob 类型。具体的java.sql.Clob, Character[], char[] 和 java.lang.String 将被持久化为 Clob 类型. java.sql.Blob, Byte[], byte[] 和 serializable type 将被持久化为 Blob 类型。
version属性映射到 "OPTLOCK" 列,entity manager 使用这个字段来检测冲突。 一般可以用 数字 或者 timestamp 类型来支持 version.
实体Bean中所有非static 非 transient 属性都可以被持久化,除非用@Transient注解。