知识大全 JBoss Envers学习笔记

Posted 2022-07-18 版本

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　　试用JBoss Envers项目有一阵子了趁Envers项目发布版也同时把学习笔记共享给大家希望对大家有所帮助

　　下面来看一下JBoss Envers项目的目的官方说明如下

　　 The Envers project aims to enable easy versioning of persistent classes All that you have to do is annotate your persistent class or some of its properties that you want to version with @Versioned For each versioned entity a table will be created which will hold the history of changes made to the entity You can then retrieve andquery historical data without much effort

　　JBoss Envers目的是根据对实体的设置提供记录执行数据变更历史的功能（数据变更版本） Envers的配置非常简单如果需要对某个实例进行历史数据版本记录只需要在实例上配置@Versioned annotation即可针对每个实体的版本的历史数据 Envers都会创建一个单独的数据表进行存储

　　目前Envers支持Hibernate和Hibernate entitymanager（JPA实现）

　　本示例以Hibernate entitymanager为例讲解其配置的方法

　　先配置 persistence xml 加入 property配置

　　 <persistence unit > <provider> hibernate ejb HibernatePersistence</provider> <class></class> <properties> <property name= hibernate dialect /> <! other hibernate properties > <property name= hibernate ejb event post insert value= jboss envers event VersionsEventListener /> <property name= hibernate ejb event post update value= jboss envers event VersionsEventListener /> <property name= hibernate ejb event post delete value= jboss envers event VersionsEventListener /> <property name= hibernate ejb event pre collection update value= jboss envers event VersionsEventListener /> <property name= hibernate ejb event pre collection remove value= jboss envers event VersionsEventListener /> <property name= hibernate ejb event post collection recreate value= jboss envers event VersionsEventListener /> </properties> </persistence unit>

　　示例代码

　　 import jboss versions Versioned; import javax persistence Entity; import javax persistence Id; import javax persistence GeneratedValue; import javax persistence Column; @Entity @Versioned public class Blog @Id @Column(length= ) private String id; @Versioned @Column(length= ) private String title; @Column(length= ) private String date; @Versioned @ManyToOne private String body; @ManyToOne private Author author; // add getters setters constructors equals and hashCode here @Entity @Versioned public class Author @Id @Column(length= ) private String id; @Versioned @Column(length= ) private String name;

　　下面是进行测试的代码

　　 // 新增操作 entityManager getTransaction() begin(); Author matthew = new Author( Matthew Xie ); Blog newBlog = new Blog( Matthew s new Blog TODOadd content here matthew); entityManager persist(matthew); entityManager persist(newBlog); entityManager getTransaction(mit();

　　 //对Blog和author进行修改操作 entityManager getTransaction() begin(); Author author = entityManager find(Author class ); Blog blog = entityManager find(Blog class ); // Changing the address s house number author setName( Matt Xie ) Author newAuthor = new Author( newAuthor ); // change blog author to newAuthor blog setAuthor(newAuthor); entityManager getTransaction(mit();

　　 //下面代码演示了如何取得历史版本数据 VersionsReader reader = VersionsReaderFactory get(entityManager); // get Blog all versions id List<Number> versions = reader getRevisions(Blog class /*blog id*/); for (Number version : versions) Blog blog = reader find(Blog class version);

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