java - Spring获取泛型类型类

Question

我知道这个问题经常被问到，但我找不到解决方案。 如何在 Spring 注入(inject)存储库中获取通用类型类名？

这是我的基础仓库

public interface UserRepository extends JpaRepository<User, Long>, IUserRepository<User>{
   User findByUsername(String username);
}

这是界面

public interface IUserRepository<T> {
   public List<T> findAllValidEtSiteAndStructure();
}

最后是实现

public class UserRepositoryImpl<T> implements IUserRepository<T> {

@PersistenceContext
private EntityManager em;

private Class< T > type;

@Override
public List<T> findAllValidEtSiteAndStructure() {
    final Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
    if (authentication instanceof UserAuthentication) {
        final User currentUser = ((UserAuthentication) authentication).getDetails();
        return (List<T>) em.createQuery("FROM " + type.getName()+ " WHERE site=:site AND structure=:structure AND valid=:valid")
                .setParameter("site", currentUser.getInstallation().getSite())
                .setParameter("structure", currentUser.getInstallation().getStructure())
                .setParameter("valid", true)
                .getResultList();
    }
    return null;
}
}

我怎样才能得到type.name？ 提前致谢

Answer 1

考虑到您使用的是 Spring Framework，请使用下面的代码片段，我已经测试过它工作正常:

ResolvableType resolvableType = ResolvableType.forClass(UserRepository.class).as(JpaRepository.class);
System.out.println(resolvableType.getGeneric(0));//User
System.out.println(resolvableType.getGeneric(1));//Long