Hibernate主键ID自动生成两种方法示例-Mysql Tutorial-php.cn

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Hibernate主键ID自动生成两种方法示例

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Jun 07, 2016 pm 05:13 PM

Hibernate主键ID自动生成两种方法示例，用uuid生成唯一的主键，用这种方法，如果对象的id为null，保存时会自动生成一个UUID，如

版本：hibernate-3.2.7

方法之一：用uuid生成唯一的主键，用这种方法，如果对象的id为null，保存时会自动生成一个UUID，如果id不为null，保存时会从数据库中找出这条记录，然后执行update,如果未找到是抛出异常。

Xxxclass.hbm.xml代码

Xxxclass.java代码

方法之二：用org.hibernate.id.UUIDHexGenerator生成唯一的主键，用这种方法，如果对象的id为null，，保存时会自动生成一个UUID，如果id不为null，保存时会从数据库中找出这条记录，然后执行update,如果未找则执行insert。

Xxxclass.hbm.xml代码

Xxxclass.java代码

Assignedidmodel.java代码

Assigncopiedid.java代码

总结：两种方法相比之下，方法一比较简单，能满足一般情况，项目中用的比较多。方法一无法处理时才用方法二，例如从其它系统数据库复制表的记录时用。

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