使用envers記錄數據變動版本

序

hibernate的envers模塊提供了一整套機制能夠用來記錄數據的變動。這裏簡單介紹一下。

1.自動配置

@SpringBootApplication
@EnableJpaRepositories(repositoryFactoryBeanClass = EnversRevisionRepositoryFactoryBean.class)
@EnableJpaAuditing(auditorAwareRef = "auditorAwareImpl")
public class EnversDemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(EnversDemoApplication.class, args);
    }
}

這裏配置@EnableJpaRepositories(repositoryFactoryBeanClass = EnversRevisionRepositoryFactoryBean.class)表示開啓envers模塊。

2.Audited註解

@Entity
@Audited
public class Book extends AuditableEntity{

    @javax.persistence.Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    private String title;

    private String author;

    private String description;

    private long price;

    private boolean valid;

    // getter and setter
}

使用@Audited標註一下這個實體類須要審計。

繼承RevisionRepository

public interface BookDao extends RevisionRepository<Book, Long, Integer>,JpaRepository<Book, Long> {
}

經過繼承RevisionRepository獲取查找revisions的查詢方法，主要以下：

@NoRepositoryBean
public interface RevisionRepository<T, ID extends Serializable, N extends Number & Comparable<N>> {
    Revision<N, T> findLastChangeRevision(ID var1);

    Revisions<N, T> findRevisions(ID var1);

    Page<Revision<N, T>> findRevisions(ID var1, Pageable var2);

    Revision<N, T> findRevision(ID var1, N var2);
}

這裏的N是指變動版本號的類型，通常Integer夠用，若是以爲不夠用能夠改成Long類型。這裏的T就是實體類。ID就是實體類的主鍵類型。

查詢變動

通過以上配置以後，就能夠正常記錄變動的每一個版本了，能夠經過以下方法來查詢，好比：

Revisions<Integer,Book> revision = bookDao.findRevisions(id);
List<Revision<Integer,Book>> data = revision.getContent();

這裏的id爲實體的id

revision的表結構

hibernate默認以實體類後綴_AUD來記錄每一個變動的版本，好比

-- ----------------------------
--  Table structure for book_aud
-- ----------------------------
DROP TABLE IF EXISTS "public"."book_aud";
CREATE TABLE "public"."book_aud" (
    "id" int8 NOT NULL,
    "rev" int4 NOT NULL,
    "revtype" int2,
    "author" varchar(255) COLLATE "default",
    "description" varchar(255) COLLATE "default",
    "price" int8,
    "title" varchar(255) COLLATE "default",
    "valid" bool
)
WITH (OIDS=FALSE);
ALTER TABLE "public"."book_aud" OWNER TO "postgres";

-- ----------------------------
--  Primary key structure for table book_aud
-- ----------------------------
ALTER TABLE "public"."book_aud" ADD PRIMARY KEY ("id", "rev") NOT DEFERRABLE INITIALLY IMMEDIATE;

-- ----------------------------
--  Foreign keys structure for table book_aud
-- ----------------------------
ALTER TABLE "public"."book_aud" ADD CONSTRAINT "fk2u9iq76nh69r6f989ae7xft9" FOREIGN KEY ("rev") REFERENCES "public"."revinfo" ("rev") ON UPDATE NO ACTION ON DELETE NO ACTION NOT DEFERRABLE INITIALLY IMMEDIATE;

若是想改表後綴的話，能夠經過org.hibernate.envers.audit_table_suffix的屬性進行配置。裏頭的rev字段表示revision的版本號，通常全局遞增。revtype字段表示操做類型，0表示新增，1表示更新，2表示刪除。

另外還有一個表是revinfo，記錄每一個變動的版本號和時間：

-- ----------------------------
--  Table structure for revinfo
-- ----------------------------
DROP TABLE IF EXISTS "public"."revinfo";
CREATE TABLE "public"."revinfo" (
    "rev" int4 NOT NULL,
    "revtstmp" int8
)
WITH (OIDS=FALSE);
ALTER TABLE "public"."revinfo" OWNER TO "postgres";

-- ----------------------------
--  Primary key structure for table revinfo
-- ----------------------------
ALTER TABLE "public"."revinfo" ADD PRIMARY KEY ("rev") NOT DEFERRABLE INITIALLY IMMEDIATE;

自定義revision entity

若是默認的envers的實現不知足你的要求的話，使用@RevisionEntity註解，替換@Audited，而後自定義listener，好比

@Entity
@RevisionEntity( ExampleListener.class )
public class ExampleRevEntity extends DefaultRevisionEntity {
    private String username;

    public String getUsername() { return username; }
    public void setUsername( String username ) { this.username = username; }
}
public class ExampleListener implements RevisionListener {

    public void newRevision( Object revisionEntity ) {
        ExampleRevEntity exampleRevEntity = ( ExampleRevEntity ) revisionEntity;
        Identity identity =
            (Identity) Component.getInstance( "org.jboss.seam.security.identity" );

        exampleRevEntity.setUsername( identity.getUsername() );
    }
}

具體的這裏就不細講了，具體能夠參考hibernate。

doc

• envers