Spring Data Jpa-不推荐使用类型规范

Question

我正在实现link：Spring data-multi-column searches中的逻辑，我希望通过firstname进行搜索。

根据链接：https://docs.spring.io/spring-data/jpa/docs/current/api/org/springframework/data/jpa/domain/specifications.html

java

public class EmployeeSpecification {
    public static Specification<Employee> textInAllColumns(String text) {
        if (!text.contains("%")) {
            text = "%" + text + "%";
        }
        final String finalText = text;

        return new Specification<Employee>() {
            @Override
            public Predicate toPredicate(Root<Employee> root, CriteriaQuery<Employee> cq, CriteriaBuilder builder) {
                return builder.or(root.getModel().getDeclaredSingularAttributes().stream().filter(a -> {
                    if (a.getJavaType().getSimpleName().equalsIgnoreCase("string")) {
                        return true;
                    } else {
                        return false;
                    }
                }).map(a -> builder.like(root.get(a.getName()), finalText)).toArray(Predicate[]::new));
            }
        };
    }
}

public interface EmployeeRepository extends JpaRepository<Employee, Long>{
    List<Employee> findAll(Specification<Employee> spec);
}

@Service
@Slf4j
public class EmployeeServiceImpl implements EmployeeService {
    @Autowired
    private EmployeeRepository employeeRepository;

    @Override
    public void findAllCustomersByFirstName(String firstName) {
        employeeRepository.findAll(Specifications.where(EmployeeSpecification.textInAllColumns(firstName)));
    }
}

错误：

在这一行有多个标记-类型规范中的（规范）不适用于参数（规范）的方法-类型规范是不推荐的

Answer 1

您的repo代码需要扩展JPaspecificationExecutor，如下所示：

public interface EmployeeRepository extends JpaRepository<Employee, Long>, 
    JpaSpecificationExecutor<Employee> {
}

JpaSpeficationExecutor有以下可以调用的方法：

public interface JpaSpecificationExecutor<T> {
    Optional<T> findOne(@Nullable Specification<T> var1);

    List<T> findAll(@Nullable Specification<T> var1);

    Page<T> findAll(@Nullable Specification<T> var1, Pageable var2);

    List<T> findAll(@Nullable Specification<T> var1, Sort var2);

    long count(@Nullable Specification<T> var1);
}

然后你可以做：

public void findAllCustomersByFirstName(String firstName) {
    employeeRepository.findAll(
            EmployeeSpecification.textInAllColumns(firstName)
    );
}

public class EmployeeSpecification {
    public static Specification<Employee> textInAllColumns(String text) {
        if (!text.contains("%")) {
            text = "%" + text + "%";
        }
        final String finalText = text;

        return  (Specification<Employee>) (root, query, builder) -> 
                builder.or(root.getModel().getDeclaredSingularAttributes().stream().filter(a -> {
                if (a.getJavaType().getSimpleName().equalsIgnoreCase("string")) {
                    return true;
                } else {
                    return false;
                }
            }).map(a -> builder.like(root.get(a.getName()), finalText)).toArray(Predicate[]::new));
    }
}