如何使用jpa实现动态插入与修改

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jpa之动态插入与修改(重写save)

1.动态插入

@Data@Entity@DynamicInsert@Table(name = "cpu_dynamics_information")@EntityListeners(AuditingEntityListener.class)public class CpuDynamicsInformation extends CommonEntity implements Serializable {  private static final long serialVersionUID = -662804563658253624L;  // cpu动态属性  private Integer cpuCore;  // cpu用户使用率  private Double cpuUseRate;  // cpu系统使用率  private Double cpuSysRate;  // cpu等待率  private Double cpuWaitRate;  // cpu空闲率  private Double cpuIdleRate;  // cpu总的使用率  private Double cpuCombineRate;  private Long serverId;}

关键注解：

@DynamicInsert@EntityListeners(AuditingEntityListener.class)

2.重写save（修改）

@SuppressWarnings(value = "all")public class JpaRepositoryReBuild extends SimpleJpaRepository {  private final JpaEntityInformation entityInformation;  private final EntityManager em;  @Autowired  public JpaRepositoryReBuild(      JpaEntityInformation entityInformation, EntityManager entityManager) {    super(entityInformation, entityManager);    this.entityInformation = entityInformation;    this.em = entityManager;  }  /** 通用save方法 ：新增/选择性更新 */  @Override  @Transactional  public  S save(S entity) {    // 获取ID    ID entityId = (ID) this.entityInformation.getId(entity);    T managedEntity;    T mergedEntity;    if (entityId == null) {      em.persist(entity);      mergedEntity = entity;    } else {      managedEntity = this.findById(entityId).get();      if (managedEntity == null) {        em.persist(entity);        mergedEntity = entity;      } else {        BeanUtils.copyProperties(entity, managedEntity, getNullProperties(entity));        em.merge(managedEntity);        mergedEntity = managedEntity;      }    }    return entity;  }  /** 获取对象的空属性 */  private static String[] getNullProperties(Object src) {    // 1.获取Bean    BeanWrapper srcBean = new BeanWrapperImpl(src);    // 2.获取Bean的属性描述    PropertyDescriptor[] pds = srcBean.getPropertyDescriptors();    // 3.获取Bean的空属性    Set properties = new HashSet<>();    for (PropertyDescriptor propertyDescriptor : pds) {      String propertyName = propertyDescriptor.getName();      Object propertyValue = srcBean.getPropertyValue(propertyName);      if (StringUtils.isEmpty(propertyValue)) {        srcBean.setPropertyValue(propertyName, null);        properties.add(propertyName);      }    }    return properties.toArray(new String[0]);  }}

3.启动类

@EnableJpaAuditing@SpringBootApplication(exclude = MongoAutoConfiguration.class)@EnableJpaRepositories(    value = {"com.fooww.research.repository", "com.fooww.research.shiro.repository"},    repositoryBaseClass = JpaRepositoryReBuild.class)public class MonitorServerApplication {  public static void main(String[] args) {    SpringApplication.run(MonitorServerApplication.class, args);  }}

关键注释：

• EnableJpaRepositories 扫描的repository包

• repositoryBaseClass 重写的save类

• EnableJpaAuditing 使@EntityListeners(AuditingEntityListener.class) 生效

扩展JPA方法，重写save方法

为什么要重构save？

jpa提供的save方法会将原有数据置为null，而大多数情况下我们只希望跟新自己传入的参数，所以便有了重写或者新增一个save方法。

本着解决这个问题，网上搜了很多解决方案，但是没有找到合适的，于是自己研究源码，先展示几个重要源码

1、SimpleJpaRepository方法实现类，由于代码过多只展示部分源码

public class SimpleJpaRepository implements JpaRepository, JpaSpecificationExecutor {    private static final String ID_MUST_NOT_BE_NULL = "The given id must not be null!";    private final JpaEntityInformation entityInformation;    private final EntityManager em;    private final PersistenceProvider provider;    @Nullable    private CrudMethodMetadata metadata;     public SimpleJpaRepository(JpaEntityInformation entityInformation, EntityManager entityManager) {        Assert.notNull(entityInformation, "JpaEntityInformation must not be null!");        Assert.notNull(entityManager, "EntityManager must not be null!");        this.entityInformation = entityInformation;        this.em = entityManager;        this.provider = PersistenceProvider.fromEntityManager(entityManager);    }     public SimpleJpaRepository(Class domainClass, EntityManager em) {        this(JpaEntityInformationSupport.getEntityInformation(domainClass, em), em);    }     public void setRepositoryMethodMetadata(CrudMethodMetadata crudMethodMetadata) {        this.metadata = crudMethodMetadata;    }     @Nullable    protected CrudMethodMetadata getRepositoryMethodMetadata() {        return this.metadata;    }     protected Class getDomainClass() {        return this.entityInformation.getJavaType();    }     private String getDeleteAllQueryString() {        return QueryUtils.getQueryString("delete from %s x", this.entityInformation.getEntityName());    }    @Transactional    public  S save(S entity) {        if (this.entityInformation.isNew(entity)) {            this.em.persist(entity);            return entity;        } else {            return this.em.merge(entity);        }    }}

2、JpaRepositoryFactoryBean

public class JpaRepositoryFactoryBean, S, ID> extends TransactionalRepositoryFactoryBeanSupport {    @Nullable    private EntityManager entityManager;     public JpaRepositoryFactoryBean(Class repositoryInterface) {        super(repositoryInterface);    }     @PersistenceContext    public void setEntityManager(EntityManager entityManager) {        this.entityManager = entityManager;    }     public void setMappingContext(MappingContext mappingContext) {        super.setMappingContext(mappingContext);    }     protected RepositoryFactorySupport doCreateRepositoryFactory() {        Assert.state(this.entityManager != null, "EntityManager must not be null!");        return this.createRepositoryFactory(this.entityManager);    }     protected RepositoryFactorySupport createRepositoryFactory(EntityManager entityManager) {        return new JpaRepositoryFactory(entityManager);    }     public void afterPropertiesSet() {        Assert.state(this.entityManager != null, "EntityManager must not be null!");        super.afterPropertiesSet();    }}　

根据源码及网上资料总结如下方案

一、重写save

优势：侵入性小，缺点将原方法覆盖。

创建JpaRepositoryReBuild方法继承SimpleJpaRepository。

直接上代码

public class JpaRepositoryReBuild extends SimpleJpaRepository {     private final JpaEntityInformation entityInformation;    private final EntityManager em;     @Autowired    public JpaRepositoryReBuild(JpaEntityInformation entityInformation, EntityManager entityManager) {        super(entityInformation, entityManager);        this.entityInformation = entityInformation;        this.em = entityManager;    }     /**     * 通用save方法 ：新增/选择性更新     */    @Override    @Transactional    public  S save(S entity) {                 //获取ID        ID entityId = (ID) this.entityInformation.getId(entity);        T managedEntity;        T mergedEntity;        if(entityId == null){            em.persist(entity);            mergedEntity = entity;        }else{            managedEntity = this.findById(entityId).get();            if (managedEntity == null) {                em.persist(entity);                mergedEntity = entity;            } else {                BeanUtils.copyProperties(entity, managedEntity, getNullProperties(entity));                em.merge(managedEntity);                mergedEntity = managedEntity;            }        }        return entity;    }     /**     * 获取对象的空属性     */    private static String[] getNullProperties(Object src) {        //1.获取Bean        BeanWrapper srcBean = new BeanWrapperImpl(src);        //2.获取Bean的属性描述        PropertyDescriptor[] pds = srcBean.getPropertyDescriptors();        //3.获取Bean的空属性        Set properties = new HashSet<>();        for (PropertyDescriptor propertyDescriptor : pds) {            String propertyName = propertyDescriptor.getName();            Object propertyValue = srcBean.getPropertyValue(propertyName);            if (StringUtils.isEmpty(propertyValue)) {                srcBean.setPropertyValue(propertyName, null);                properties.add(propertyName);            }        }        return properties.toArray(new String[0]);    }}

启动类加上JpaRepositoryReBuild 方法

@EnableJpaRepositories(value = "com.XXX", repositoryBaseClass = JpaRepositoryReBuild.class)@SpringBootApplication@EnableDiscoveryClient // 即消费也注册public class SystemApplication {     public static void main(String[] args) {        SpringApplication.run(SystemApplication.class, args);    }     }

二、扩张jpa方法

1、新建新增方法接口BaseRepository

@NoRepositoryBeanpublic interface BaseRepository extends JpaRepository {     /**     * 保存但不覆盖原有数据     * @param entity     * @return     */    T saveNotNull(T entity);}

2、创建BaseRepositoryImpl方法

@NoRepositoryBeanpublic class BaseRepositoryImpl extends SimpleJpaRepository implements BaseRepository {      private final JpaEntityInformation entityInformation;    private final EntityManager em;       public BaseRepositoryImpl(JpaEntityInformation entityInformation, EntityManager entityManager) {        super(entityInformation,entityManager);        this.entityInformation = entityInformation;        this.em = entityManager;    }     public BaseRepositoryImpl(Class domainClass, EntityManager em) {        this(JpaEntityInformationSupport.getEntityInformation(domainClass, em), em);    }     @Override    @Transactional    public T saveNotNull(T entity) {         //获取ID        ID entityId = (ID) this.entityInformation.getId(entity);        T managedEntity;        T mergedEntity;        if(entityId == null){            em.persist(entity);            mergedEntity = entity;        }else{            managedEntity = this.findById(entityId).get();            if (managedEntity == null) {                em.persist(entity);                mergedEntity = entity;            } else {                BeanUtils.copyProperties(entity, managedEntity, getNullProperties(entity));                em.merge(managedEntity);                mergedEntity = managedEntity;            }        }        return mergedEntity;    }      private static String[] getNullProperties(Object src) {        //1.获取Bean        BeanWrapper srcBean = new BeanWrapperImpl(src);        //2.获取Bean的属性描述        PropertyDescriptor[] pds = srcBean.getPropertyDescriptors();        //3.获取Bean的空属性        Set properties = new HashSet<>();        for (PropertyDescriptor propertyDescriptor : pds) {            String propertyName = propertyDescriptor.getName();            Object propertyValue = srcBean.getPropertyValue(propertyName);            if (StringUtils.isEmpty(propertyValue)) {                srcBean.setPropertyValue(propertyName, null);                properties.add(propertyName);            }        }        return properties.toArray(new String[0]);    }}

3、创建工厂BaseRepositoryFactory

public class BaseRepositoryFactory, T, ID extends Serializable> extends JpaRepositoryFactoryBean {     public BaseRepositoryFactory(Class repositoryInterface) {        super(repositoryInterface);    }     @Override    protected RepositoryFactorySupport createRepositoryFactory(EntityManager em) {        return new MyRepositoryFactory(em);    }     private static class MyRepositoryFactory extends JpaRepositoryFactory {         private final EntityManager em;        public MyRepositoryFactory(EntityManager em) {            super(em);            this.em = em;        }         @Override        protected Object getTargetRepository(RepositoryInformation information) {            return new BaseRepositoryImpl((Class) information.getDomainType(), em);        }         @Override        protected Class getRepositoryBaseClass(RepositoryMetadata metadata) {            return BaseRepositoryImpl.class;        }     } }

4、启动类引入

@EnableJpaRepositories(repositoryFactoryBeanClass = BaseRepositoryFactory.class, basePackages ="com.XXX")@SpringBootApplication@EnableDiscoveryClient // 即消费也注册public class SystemApplication {     public static void main(String[] args) {        SpringApplication.run(SystemApplication.class, args);    }}

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