如何使用Spring JPA删除数据：delete方法的完整示例

@Transactional
@Override
public void deleteById(ID id) {
   Assert.notNull(id, ID_MUST_NOT_BE_NULL);
   delete(findById(id).orElseThrow(() -> new EmptyResultDataAccessException(
         String.format("No %s entity with id %s exists!", entityInformation.getJavaType(), id), 1)));
}

@Override
@Transactional
@SuppressWarnings("unchecked")
public void delete(T entity) {
   Assert.notNull(entity, "Entity must not be null!");
   if (entityInformation.isNew(entity)) {
      return;
   }
   Class<?> type = ProxyUtils.getUserClass(entity);
   T existing = (T) em.find(type, entityInformation.getId(entity));
   // if the entity to be deleted doesn't exist, delete is a NOOP
   if (existing == null) {
      return;
   }
   em.remove(em.contains(entity) ? entity : em.merge(entity));
}

@Transactional
public void deleteById(Integer id){
    userDao.deleteById(id);
}

/**
 * 通过id进行删除数据
 * @param id
 */
@GetMapping("/deleteById")
public void deleteById(Integer id){
	userService.deleteById(id);
}

Hibernate: select user0_.id as id1_0_0_, user0_.age as age2_0_0_, user0_.name as name3_0_0_ from user user0_ where user0_.id=?
Hibernate: delete from user where id=?

@Override
@Transactional
public void deleteAllById(Iterable<? extends ID> ids) {
   Assert.notNull(ids, "Ids must not be null!");
   for (ID id : ids) {
      deleteById(id);
   }
}

@Override
@Transactional
public void deleteAll(Iterable<? extends T> entities) {
   Assert.notNull(entities, "Entities must not be null!");
   for (T entity : entities) {
      delete(entity);
   }
}

@Override
@Transactional
public void deleteAll() {
   for (T element : findAll()) {
      delete(element);
   }
}

@Transactional
public void deleteAllById(Iterable ids){
	userDao.deleteAllById(ids);
}

/**
 * 通过id进行批量删除
 * @param ids
 */
@GetMapping("/deleteAllById")
public void deleteAllById(Integer[] ids){
	userService.deleteAllById(Arrays.asList(ids));
}

public static final String DELETE_ALL_QUERY_STRING = "delete from %s x";
@Override
@Transactional
public void deleteAllInBatch(Iterable<T> entities) {
   Assert.notNull(entities, "Entities must not be null!");
   if (!entities.iterator().hasNext()) {
      return;
   }
   applyAndBind(getQueryString(DELETE_ALL_QUERY_STRING, entityInformation.getEntityName()), entities, em)
         .executeUpdate();
}

/**
 * Creates a where-clause referencing the given entities and appends it to the given query string. Binds the given
 * entities to the query.
 *
 * @param <T> type of the entities.
 * @param queryString must not be {@literal null}.
 * @param entities must not be {@literal null}.
 * @param entityManager must not be {@literal null}.
 * @return Guaranteed to be not {@literal null}.
 */
public static <T> Query applyAndBind(String queryString, Iterable<T> entities, EntityManager entityManager) {
   Assert.notNull(queryString, "Querystring must not be null!");
   Assert.notNull(entities, "Iterable of entities must not be null!");
   Assert.notNull(entityManager, "EntityManager must not be null!");
   Iterator<T> iterator = entities.iterator();
   if (!iterator.hasNext()) {
      return entityManager.createQuery(queryString);
   }
   String alias = detectAlias(queryString);
   StringBuilder builder = new StringBuilder(queryString);
   builder.append(" where");
   int i = 0;
   while (iterator.hasNext()) {
      iterator.next();
      builder.append(String.format(" %s = ?%d", alias, ++i));
      if (iterator.hasNext()) {
         builder.append(" or");
      }
   }
   Query query = entityManager.createQuery(builder.toString());
   iterator = entities.iterator();
   i = 0;
   while (iterator.hasNext()) {
      query.setParameter(++i, iterator.next());
   }
   return query;
}

Hibernate: delete from user where id=? or id=? or id=?

public static final String DELETE_ALL_QUERY_BY_ID_STRING = "delete from %s x where %s in :ids";
@Override
@Transactional
public void deleteAllByIdInBatch(Iterable<ID> ids) {
   Assert.notNull(ids, "Ids must not be null!");
   if (!ids.iterator().hasNext()) {
      return;
   }
   if (entityInformation.hasCompositeId()) {
      List<T> entities = new ArrayList<>();
      // generate entity (proxies) without accessing the database.
      ids.forEach(id -> entities.add(getReferenceById(id)));
      deleteAllInBatch(entities);
   } else {
      String queryString = String.format(DELETE_ALL_QUERY_BY_ID_STRING, entityInformation.getEntityName(),
            entityInformation.getIdAttribute().getName());
      Query query = em.createQuery(queryString);
      /**
       * Some JPA providers require {@code ids} to be a {@link Collection} so we must convert if it's not already.
       */
      if (Collection.class.isInstance(ids)) {
         query.setParameter("ids", ids);
      } else {
         Collection<ID> idsCollection = StreamSupport.stream(ids.spliterator(), false)
               .collect(Collectors.toCollection(ArrayList::new));
         query.setParameter("ids", idsCollection);
      }
      query.executeUpdate();
   }
}

Hibernate: delete from user where id in (? , ? , ?)

@Override
@Transactional
public void deleteAllInBatch() {
   em.createQuery(getDeleteAllQueryString()).executeUpdate();
}
public static final String DELETE_ALL_QUERY_STRING = "delete from %s x";
private String getDeleteAllQueryString() {
   return getQueryString(DELETE_ALL_QUERY_STRING, entityInformation.getEntityName());
}