为什么 Spring-Data-JPA 异步不起作用？

Question

我正在尝试使用 Spring Boot 和 Spring data JPA 创建一个非阻塞休息服务。

如何使用 Spring Data JPA @Async 支持对实体进行异步保存。尽管其他选择似乎在同一实体上工作，但下面的代码对我不起作用。

我正在尝试在 JPA 存储库中执行此操作。这是完整的存储库：除了保存。这些方法运行良好，我可以测试它们

public interface LoanRepository extends JpaRepository<Loan,Long> {

@Query("select distinct loan from Loan loan left join fetch loan.collaterals left join fetch loan.partys")
@Async
CompletableFuture<List<Loan>> findAllWithEagerRelationships();

@Query("select loan from Loan loan left join fetch loan.collaterals left join fetch loan.partys where loan.id =:id")
@Async
CompletableFuture<Loan> findOneWithEagerRelationships(@Param("id") Long id);

@Async
void delete(Long id);

}

但是，当我尝试添加以下保存方法时：

    @Async
    <S extends CompletableFuture<Loan>> S save(Loan loan);

我收到一个明显的编译错误，上面写着"The method save(Loan) is ambiguous for the type LoanRepository"

我尝试将其更改为：

    @Async
    <S extends CompletableFuture<Loan>> S save(S loan);

但我在启动时遇到异常，java.lang.UnsupportedOperationException: null原因是：

Caused by: java.lang.NullPointerException: null
at org.springframework.data.repository.query.QueryMethod.potentiallyUnwrapReturnTypeFor(QueryMethod.java:244)

Spring Data JPA 文档中关于异步支持的保存部分并不清楚。 Spring Data JPA 异步支持

Answer 1

I had this issue myself and after trying some variations this seems to work:

@Async
@Override
<S extends Loan> CompletableFuture<S> save(S loan);