如何在Hibernate中维护表的历史记录

为了维护数据库的历史记录或跟踪数据库表行的修改，我们创建了一个版本表，其中包含与原始表相同的字段。每当原始表被更改时，我们都会在版本表中创建另一个条目。因此，对于每个更新查询，我们都必须在版本表中编写一个插入查询。休眠中有一个模块可以管理对象的简单审核，而我们不必自己编写单独的插入查询。

Hibernate Envers提供了内置的机制来维护数据库中对象的历史记录。 Envers是Hibernate的库，它将帮助我们轻松实现审核功能。这是由Adam Warski创建的。从Hibernate 3.5开始，Envers作为Hibernate核心模块包含在内。让我们举一个例子，说明如何使用Envers维护对象的历史记录。

这是Envers的pom依赖关系（版本将与您的休眠核心和实体管理器相同）：

<dependency>  <groupId>org.hibernate</groupId> <artifactId>hibernate-envers</artifactId> <version>4.0.1.Final</version> 
</dependency>

您必须在hibernate.cfg.xml中配置侦听器。

<mapping class="com.javaroots.model.User" /><listener class="org.hibernate.envers.event.AuditEventListener" type="post-insert"/><listener class="org.hibernate.envers.event.AuditEventListener" type="post-update"/><listener class="org.hibernate.envers.event.AuditEventListener" type="post-delete"/><listener class="org.hibernate.envers.event.AuditEventListener" type="pre-collection-update"/><listener class="org.hibernate.envers.event.AuditEventListener" type="pre-collection-remove"/><listener class="org.hibernate.envers.event.AuditEventListener" type="post-collection-recreate"/>

让我们以User类为例。我们要跟踪用户字段的更新。要为用户对象启用历史记录，我们需要使用@Audited批注。如果在类级别上使用，则该类中的所有字段都将被视为可审计的，并且任何字段中的更改将在audit table中具有新条目。如果我们希望某些字段不包含在历史记录中，则可以使用@NotAudited批注。如果更改了NotAudited字段，那么审计表中将没有任何条目。这是用户类：

package com.javaroots.model;import javax.persistence.Column;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Entity;import org.hibernate.envers.Audited;
import org.hibernate.envers.NotAudited;/*** * * @author Abhishek Somani* */
@Entity
@Audited
public class User {@Id@GeneratedValue(strategy = GenerationType.AUTO)private Long id;@Column(length = 20)private String firstName;@Column(length = 20)private String lastName;@Column(length = 20)@NotAuditedprivate String password;public Long getId() {return id;}public void setId(Long id) {this.id = id;}public String getFirstName() {return firstName;}public void setFirstName(String firstName) {this.firstName = firstName;}public String getLastName() {return lastName;}public void setLastName(String lastName) {this.lastName = lastName;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}}

这是测试类，我们在其中创建用户表中的条目，然后更新它的field。

package com.javaroots.main;import org.hibernate.Session;import com.javaroots.model.User;
import com.javaroots.util.HibernateUtil;public class HibernateTest {public static void main(String[] args) {Session session = HibernateUtil.getSessionFactory().openSession();//one entry will be created in user table //and audit entry created in user_aud tablesession.beginTransaction();User u = new User();u.setFirstName("Amitabh");u.setLastName("bachhan");u.setPassword("God");session.save(u);session.getTransaction().commit();session.beginTransaction();User amitabh = (User)session.get(User.class,1l);amitabh.setFirstName("Abhishek");session.getTransaction().commit();//no entry in audit table if we change password field//because this field is marked as @notAuditedsession.beginTransaction();amitabh = (User)session.get(User.class,1l);amitabh.setPassword("NotGod");session.getTransaction().commit();//get specific revisionAuditReader reader = AuditReaderFactory.get(HibernateUtil.getSessionFactory().openSession());User abhishek = (User) reader.find(User.class, new Long(1), 2);System.out.println(abhishek.getFirstName() + " " + abhishek.getLastName());//get all revisionList versions = reader.getRevisions(User.class, new Long(1));for (Number number : versions) {System.out.print(number + " ");}}}

首先，在用户表中创建一个用户行。在user_aud中创建一个具有修订ID和用户表字段的行。在revinfo表中使用修订ID和时间戳创建一行。这两个条目由envers自动完成。这是sql查询和表结构：

Hibernate: insert intoUser(firstName, lastName, password) values(?, ?, ?)
Hibernate: insert intoREVINFO(REVTSTMP) values(?)
Hibernate: insert intoUser_AUD(REVTYPE, firstName, lastName, id, REV) values(?, ?, ?, ?, ?)
Hibernate: updateUser setfirstName=?,lastName=?,password=? whereid=?
Hibernate: insert intoREVINFO(REVTSTMP) values(?)
Hibernate: insert intoUser_AUD(REVTYPE, firstName, lastName, id, REV) values(?, ?, ?, ?, ?)
Hibernate: updateUser setfirstName=?,lastName=?,password=? whereid=?
Hibernate: selectuser_aud0_.id as id4_,user_aud0_.REV as REV4_,user_aud0_.REVTYPE as REVTYPE4_,user_aud0_.firstName as firstName4_,user_aud0_.lastName as lastName4_ fromUser_AUD user_aud0_ whereuser_aud0_.REV=(selectmax(user_aud1_.REV) fromUser_AUD user_aud1_ whereuser_aud1_.REV<=? and user_aud0_.id=user_aud1_.id) and user_aud0_.REVTYPE<>? and user_aud0_.id=?
Abhishek bachhan
Hibernate: selectuser_aud0_.REV as col_0_0_ fromUser_AUD user_aud0_ cross joinREVINFO defaultrev1_ whereuser_aud0_.id=? and user_aud0_.REV=defaultrev1_.REV order byuser_aud0_.REV asc

mysql> select * from user;
+----+-----------+----------+---------------+
| id | firstName | lastName | password      |
+----+-----------+----------+---------------+
|  1 | Amitabh   | bachchan    | God|
+----+-----------+----------+---------------+
1 row in set (0.03 sec)mysql> select * from user_aud;
+----+-----+---------+-----------+----------+
| id | REV | REVTYPE | firstName | lastName |
+----+-----+---------+-----------+----------+
|  1 |   1 |       0 | Amitabh   | bachchan    |
+----+-----+---------+-----------+----------+
1 row in set (0.00 sec)mysql> select * from revinfo;
+-----+---------------+
| REV | REVTSTMP      |
+-----+---------------+
|   1 | 1375956506278|
+-----+---------------+
1 row in set (0.00 sec)

mysql> select * from user;
+----+-----------+----------+----------------+
| id | firstName | lastName | password       |
+----+-----------+----------+----------------+
|  1 | Amitabh   | bachchan| NotGod |
+----+-----------+----------+----------------+
1 row in set (0.00 sec)mysql> select * from user_aud;
+----+-----+---------+-----------+----------+
| id | REV | REVTYPE | firstName | lastName |
+----+-----+---------+-----------+----------+
|  1 |   1 |       0 | Amitabh   | bachchan |
|  1 |   2 |       1 | Abhishek  | bachchan|
+----+-----+---------+-----------+----------+
2 rows in set (0.00 sec)mysql> select * from revinfo;
+-----+---------------+
| REV | REVTSTMP      |
+-----+---------------+
|   1 | 1375956506278|
|   2 | 1375956506328|
+-----+---------------+
2 rows in set (0.00 sec)