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); } }