记录数据修改前后的变化

发表于 2023-12-10 更新于 2024-10-20 分类于 JAVA ， JPA 阅读次数：本文字数： 1.3k 阅读时长 ≈ 4 分钟

背景

追踪数据变化在各种审查场景中是一个常见的需求. 在这里我记录一个常见的错误实现, 并提供一个从基础到完整可用的框架实现. 在这里我选用 Hibernate 6.4.Final 作为框架依赖.

常见的错误实现

依赖暴力反射
字段存在性能问题
在现代 ORM 框架下会遇到大量常见的运行时错误


// 自定义注解
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface ForUpdate {
    String fieldName() default "";

    /**
     * 获取变更内容.
     * @param newBean 更改前的Bean
     * @param oldBean 更改后的Bean
     */
     static <T> String getChangedFields(T newBean, T oldBean){
        Field[] fields = newBean.getClass().getDeclaredFields();
        StringBuilder builder = new StringBuilder();
        for(Field field : fields) {
            field.setAccessible(true);
            if (field.isAnnotationPresent(ForUpdate.class)) {
                try {
                    Object newValue = field.get(newBean);
                    Object oldValue = field.get(oldBean);
                    if(!Objects.equals(newValue, oldValue)) {
                        builder.append(field.getAnnotation(ForUpdate.class).fieldName()); //获取字段名称
                        builder.append(": 【更改前：");
                        builder.append(newValue);
                        builder.append(", 更改后：");
                        builder.append(oldValue);
                        builder.append("】\n");
                    }
                } catch (Exception e) {
                    System.out.println(e);
                }
            }
        }
        return builder.toString();
    }
}

雏形 - JPA

根据 JPA规范, ORM 必须支持实体生命回调及动态值刷新.

An update to the state of an entity includes both the assignment of a new value to a persistent property or field of the entity as well as the modification of a mutable value of a persistent property or field[26].

以下是根据规则1作的一个简易的模型:

package com.pancc.up.simple.entity;

import jakarta.persistence.*;
import lombok.Getter;
import lombok.Setter;
import lombok.extern.log4j.Log4j2;


/**
 * @author Siweipancc on 2023/12/8
 */

@Entity
@Setter
@Getter
@Log4j2
public class Room {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", nullable = false)
    private Long id;

    String name;

    Integer size = 1;

    Integer cups = 0;

    @Version
    Long version;

    @PreUpdate
    public void preUpdate() {
        log.info("update, what properties?");
    }
}

改进1 - 规则 2 的遵守

以上代码虽 HOOK 了更新生命回调, 但无法确定变动的字段以及旧值. 因此需要依赖 Hibernate 等现代 ORM 的脏值检测与更加深入的生命回调. 为 Hibernate 编写并声明如下 Service:

package com.pancc.up.simple.spi;

import lombok.extern.slf4j.Slf4j;
import org.hibernate.boot.Metadata;
import org.hibernate.boot.spi.BootstrapContext;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.event.service.spi.EventListenerRegistry;
import org.hibernate.event.spi.EventType;
import org.hibernate.event.spi.PostUpdateEvent;
import org.hibernate.event.spi.PostUpdateEventListener;
import org.hibernate.integrator.spi.Integrator;
import org.hibernate.metamodel.mapping.AttributeMapping;
import org.hibernate.persister.entity.EntityPersister;
import org.hibernate.service.spi.SessionFactoryServiceRegistry;


/**
 * @author Siweipancc on 2023/12/8
 */
@Slf4j
public class MonitorIntegrator implements Integrator, PostUpdateEventListener {

    @Override
    public void integrate(Metadata metadata, BootstrapContext bootstrapContext, SessionFactoryImplementor serviceRegistry) {
        EventListenerRegistry eventListenerRegistry = serviceRegistry.getServiceRegistry().getService(EventListenerRegistry.class);
        assert eventListenerRegistry != null;
        eventListenerRegistry.appendListeners(EventType.POST_COMMIT_UPDATE, this);

    }

    @Override
    public void disintegrate(SessionFactoryImplementor sessionFactory, SessionFactoryServiceRegistry serviceRegistry) {

    }

    @Override
    public void onPostUpdate(PostUpdateEvent event) {
        EntityPersister persister = event.getPersister();
        Class<?> mappedClass = persister.getMappedClass();
        log.info("entity update: {} ", mappedClass);

        for (int idx : event.getDirtyProperties()) {
            AttributeMapping attributeMapping = persister.getAttributeMapping(idx);
            String attributeName = attributeMapping.getAttributeName();
            Object oldValue = event.getOldState()[idx];
            Object newValue = event.getState()[idx];
            log.info("{} changed from: [{}] to [{}]", attributeName, oldValue, newValue);

        }
    }

    @Override
    public boolean requiresPostCommitHandling(EntityPersister persister) {
        return true;
    }
}

以上代码完成了以下任务:

实现了 Hibernate 的插件接口 Integrator 与实体事件更新后接口 PostUpdateEventListener
根据脏值获取到字段名与前后值

改进2 - 自定义信息

自定义注解

参考错误实现提供自定义信息, 根据 JPA 的字段访问规则 Access Type, 我们的注解需要支持两个位置:

package com.pancc.up.simple.annotation;

import java.lang.annotation.*;

/**
 * @author Siweipancc on 2023/12/10
 */
@Target({ElementType.FIELD, ElementType.METHOD})
@Documented
@Retention(RetentionPolicy.RUNTIME)
public @interface LogProperty {

    String value();
}

改造实体类


package com.pancc.up.simple.entity;

import com.pancc.up.simple.annotation.LogProperty;
import jakarta.persistence.*;
import lombok.Getter;
import lombok.Setter;
import lombok.extern.log4j.Log4j2;


/**
 * @author Siweipancc on 2023/12/8
 */

@Entity
@Setter
@Log4j2
@Getter
public class Room {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", nullable = false)
    @Getter
    private Long id;

    @LogProperty("名字")
    @Getter
    String name;

    @Access(AccessType.PROPERTY)
    Integer size = 1;

    /**
     * @see org.hibernate.property.access.spi.Getter#getMember()
     */
    @LogProperty("大小")
    public Integer getSize() {
        return size;
    }

    @LogProperty("配套")
    @Getter
    Integer cups = 0;

    @Version
    Long version;
}

改造 Service


package com.pancc.up.simple.spi;

import com.pancc.up.simple.annotation.LogProperty;
import lombok.extern.slf4j.Slf4j;
import org.hibernate.boot.Metadata;
import org.hibernate.boot.spi.BootstrapContext;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.event.service.spi.EventListenerRegistry;
import org.hibernate.event.spi.EventType;
import org.hibernate.event.spi.PostUpdateEvent;
import org.hibernate.event.spi.PostUpdateEventListener;
import org.hibernate.integrator.spi.Integrator;
import org.hibernate.metamodel.mapping.AttributeMapping;
import org.hibernate.persister.entity.EntityPersister;
import org.hibernate.service.spi.SessionFactoryServiceRegistry;

import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Member;
import java.util.Optional;


/**
 * @author Siweipancc on 2023/12/8
 */
@Slf4j
public class MonitorIntegrator implements Integrator, PostUpdateEventListener {

    @Override
    public void integrate(Metadata metadata, BootstrapContext bootstrapContext, SessionFactoryImplementor serviceRegistry) {
        EventListenerRegistry eventListenerRegistry = serviceRegistry.getServiceRegistry().getService(EventListenerRegistry.class);
        assert eventListenerRegistry != null;
        eventListenerRegistry.appendListeners(EventType.POST_COMMIT_UPDATE, this);
    }

    @Override
    public void disintegrate(SessionFactoryImplementor sessionFactory, SessionFactoryServiceRegistry serviceRegistry) {
    }

    @Override
    public void onPostUpdate(PostUpdateEvent event) {
        EntityPersister persister = event.getPersister();
        Class<?> mappedClass = persister.getMappedClass();
        log.info("entity update: {} ", mappedClass);

        for (int idx : event.getDirtyProperties()) {
            AttributeMapping attributeMapping = persister.getAttributeMapping(idx);
            String attributeName = attributeMapping.getAttributeName();
            Object oldValue = event.getOldState()[idx];
            Object newValue = event.getState()[idx];
            Member member = attributeMapping.getPropertyAccess().getGetter().getMember();
            String msg = Optional.ofNullable(member).filter(AnnotatedElement.class::isInstance).map(AnnotatedElement.class::cast)
                    .map(x -> x.getAnnotation(LogProperty.class)).map(LogProperty::value).orElse(attributeName);
            log.info("{}({}) changed from: [{}] to [{}]", attributeName, msg, oldValue, newValue);

        }
    }

    @Override
    public boolean requiresPostCommitHandling(EntityPersister persister) {
        return true;
    }
}

至此, 我们可以根据注解在字段或者方法上动态地获得自定义信息.

改进3 - 融合 IOC 框架

对于 IOC 环境, 为了更好的融合与使用自动依赖注入特性, 例如 Spring , 我们将 Service 声明文件删除, 删除 Integrator 接口声明, 因此以上的 Service 代码可变为如下:

改造 Service

package com.pancc.up.simple.spi;

import com.pancc.up.simple.annotation.LogProperty;
import lombok.extern.slf4j.Slf4j;
import org.hibernate.event.spi.PostUpdateEvent;
import org.hibernate.event.spi.PostUpdateEventListener;
import org.hibernate.metamodel.mapping.AttributeMapping;
import org.hibernate.persister.entity.EntityPersister;

import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Member;
import java.util.Optional;


/**
 * @author Siweipancc on 2023/12/8
 */
@Slf4j
public class MonitorIntegrator implements PostUpdateEventListener {

    @Override
    public void onPostUpdate(PostUpdateEvent event) {
        EntityPersister persister = event.getPersister();
        Class<?> mappedClass = persister.getMappedClass();
        log.info("entity update: {} ", mappedClass);

        for (int idx : event.getDirtyProperties()) {
            AttributeMapping attributeMapping = persister.getAttributeMapping(idx);
            String attributeName = attributeMapping.getAttributeName();
            Object oldValue = event.getOldState()[idx];
            Object newValue = event.getState()[idx];
            Member member = attributeMapping.getPropertyAccess().getGetter().getMember();
            String msg = Optional.ofNullable(member).filter(AnnotatedElement.class::isInstance).map(AnnotatedElement.class::cast)
                    .map(x -> x.getAnnotation(LogProperty.class)).map(LogProperty::value).orElse(attributeName);
            log.info("{}({}) changed from: [{}] to [{}]", attributeName, msg, oldValue, newValue);

        }
    }

    @Override
    public boolean requiresPostCommitHandling(EntityPersister persister) {
        return true;
    }
}

增加配置类

package com.pancc.up.simple.spi;

import jakarta.persistence.EntityManagerFactory;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.event.service.spi.EventListenerRegistry;
import org.hibernate.event.spi.EventType;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * @author Siweipancc on 2023/12/10
 */
@Configuration
public class MConfig {
    @Configuration
    static class config {
        @Bean
        public MonitorIntegrator monitorIntegrator() {
            return new MonitorIntegrator();
        }
    }

    @Autowired
    public void monitorIntegrator(MonitorIntegrator monitorIntegrator, EntityManagerFactory entityManagerFactory) {
        SessionFactoryImplementor sessionFactory = entityManagerFactory.unwrap(SessionFactoryImplementor.class);
        EventListenerRegistry eventListenerRegistry = sessionFactory.getServiceRegistry().getService(EventListenerRegistry.class);
        assert eventListenerRegistry != null;
        eventListenerRegistry.appendListeners(EventType.POST_COMMIT_UPDATE, monitorIntegrator);
    }
}

改造效果

2023-12-10T23:48:38.719+08:00  INFO 21480 --- [nio-8080-exec-4] c.pancc.up.simple.spi.MonitorIntegrator  : entity update: class com.pancc.up.simple.entity.Room 
2023-12-10T23:48:38.719+08:00  INFO 21480 --- [nio-8080-exec-4] c.pancc.up.simple.spi.MonitorIntegrator  : cups(配套) changed from: [3] to [5]
2023-12-10T23:48:38.719+08:00  INFO 21480 --- [nio-8080-exec-4] c.pancc.up.simple.spi.MonitorIntegrator  : size(大小) changed from: [2] to [4]
2023-12-10T23:48:38.719+08:00  INFO 21480 --- [nio-8080-exec-4] c.pancc.up.simple.spi.MonitorIntegrator  : version(version) changed from: [20] to [21]

注意

追踪值时, 应注意值的类型, 序列化值的尽量为 Basic 类型, 日志也按照单表思想记录

额外资料

Hibernate_Integration

JPA3.1