Hibernate Id生成策略

 <!-- UUID 生成策略   -->
<!-- domain ID类型 必须是 String  -->
<!-- 类似于网卡生成的类型   -->
<class name="Person">
        <id name="id">
        <generator class="uuid"></generator>
        </id>
        <property name="name"/>
        <property name="weight"/>
    </class>

<!--native 生成策略-->
<!--domain ID类型 必须是 int-->
<!--由数据库自动递增-->

 <class name="Person">
        <id name="id">
        <generator class="native"></generator>
        </id>
        <property name="name"/>
        <property name="weight"/>
    </class>

Annotation的ID生成策略

package com.meiyoudao.domain;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity
public class PersonAnno {
	
	
	private int id;
	private String name;
	private String weight;
	
	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)//不能用于oracle，因为不支持IDENTITY; oracle是SEQUENCE
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getWeight() {
		return weight;
	}
	public void setWeight(String weight) {
		this.weight = weight;
	}

}

指定SEQUENCE名

package com.meiyoudao.domain;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.SequenceGenerator;

@Entity
@SequenceGenerator(name = "sequence_ora",sequenceName="SEQUENCE_ORACLE") //数据库中的sequence名:SEQUENCE_ORACLE
				   														 //还有一些可配参数如initialValue 初始化值;allocationSize每次主键值增加的大小
public class PersonAnno {
	
	
	private int id;
	private String name;
	private String weight;
	
	@Id
	@GeneratedValue(strategy=GenerationType.SEQUENCE,generator="sequence_ora")//指定定义的sequence名
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getWeight() {
		return weight;
	}
	public void setWeight(String weight) {
		this.weight = weight;
	}

}

用表存储自增长值

package com.meiyoudao.domain;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.TableGenerator;

@Entity
@TableGenerator(name="sequence_mysql",table="generator_mysql")
//可以设置表名,表列名,表初始值等等信息
public class PersonAnno {
	
	
	private int id;
	private String name;
	private String weight;
	
	@Id
	@GeneratedValue(strategy=GenerationType.TABLE,generator="sequence_mysql")
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getWeight() {
		return weight;
	}
	public void setWeight(String weight) {
		this.weight = weight;
	}

}