使用jpa之动态插入与修改(重写save)

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<T, ID> extends SimpleJpaRepository<T, ID> {
 private final JpaEntityInformation<T, ?> entityInformation;
 private final EntityManager em;
 @Autowired
 public JpaRepositoryReBuild(
     JpaEntityInformation<T, ?> 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 extends T> 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<String> 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<T, ID> implements JpaRepository<T, ID>, JpaSpecificationExecutor<T> {
   private static final String ID_MUST_NOT_BE_NULL = "The given id must not be null!";
   private final JpaEntityInformation<T, ?> entityInformation;
   private final EntityManager em;
   private final PersistenceProvider provider;
   @Nullable
   private CrudMethodMetadata metadata;

public SimpleJpaRepository(JpaEntityInformation<T, ?> 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<T> 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<T> getDomainClass() {
       return this.entityInformation.getJavaType();
   }

private String getDeleteAllQueryString() {
       return QueryUtils.getQueryString("delete from ％s x", this.entityInformation.getEntityName());
   }
   @Transactional
   public <S extends T> 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<T extends Repository<S, ID>, S, ID> extends TransactionalRepositoryFactoryBeanSupport<T, S, ID> {
   @Nullable
   private EntityManager entityManager;
   public JpaRepositoryFactoryBean(Class<? extends T> 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<T, ID> extends SimpleJpaRepository<T, ID> {
   private final JpaEntityInformation<T, ?> entityInformation;
   private final EntityManager em;
   @Autowired
   public JpaRepositoryReBuild(JpaEntityInformation<T, ?> 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 extends T> 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<String> 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

@NoRepositoryBean
public interface BaseRepository<T, ID extends Serializable> extends JpaRepository<T, ID> {
   /**
    * 保存但不覆盖原有数据
    * @param entity
    * @return
    */
   T saveNotNull(T entity);
}

2、创建BaseRepositoryImpl方法

@NoRepositoryBean
public class BaseRepositoryImpl<T, ID extends Serializable> extends SimpleJpaRepository<T, ID> implements BaseRepository<T, ID> {  
   private final JpaEntityInformation<T, ?> entityInformation;
   private final EntityManager em;  
   public BaseRepositoryImpl(JpaEntityInformation<T, ?> entityInformation, EntityManager entityManager) {
       super(entityInformation,entityManager);
       this.entityInformation = entityInformation;
       this.em = entityManager;
   }

public BaseRepositoryImpl(Class<T> 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<String> 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<R extends JpaRepository<T, ID>, T, ID extends Serializable> extends JpaRepositoryFactoryBean<R, T, ID> {
   public BaseRepositoryFactory(Class<? extends R> 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);
   }
}

来源：https://www.cnblogs.com/zhouwenyang/p/11136598.html