JAX-RS（或 Quarkus）使用子资源进行反向路由

Question

我有一个

ContainerRequestFilter

，它为我的 JAX-RS/Quarkus 应用程序中调用的每个端点收集一些指标。这需要访问每个资源上的

@Path

注释中指定的 URI 模式（“/api/users/{userId}”，而不是像“/api/users/1711”这样的已解析 URL）

我使用以下代码，该代码对于简单资源非常有效，但对于嵌套资源则失败：

class MyFilter implements ContainerRequestFilter {

    @Context
    ResourceInfo resourceInfo

    ...

    private String getUri() {
        var uriBuilder = UriBuilder.fromResource(resourceInfo.getResourceClass());
        var pathAnnotationOnMethod = resourceInfo.getResourceMethod().getAnnotation(Path.class);
        if (pathAnnotationOnMethod != null) {
            uriBuilder = uriBuilder.path(resourceInfo.getResourceMethod());
        }
        return uriBuilder.toTemplate();
    }
}

此方法不适用于如下所示的嵌套资源：

@Path("api/users")
class UsersResource {

    @Inject
    UserResource userResource;

    @Inject
    UserAccessService userAccessService;

    @Context
    ResourceContext resourceContext;

    @Path("{id}")
    public UserResource user(@PathParam("id") long userId) {
        userAccessService.ensureAccessTo(userId);
        return resourceContext.initResource(userResource);
    }

}

@RequestScoped
class UserResource {

    @GET
    public Response getUser(@PathParam("id") long userId) {
      ...
    }
}

它抛出一个异常，抱怨

UserResource

 没有 

@Path

 注释。

所以我的问题是：如何解析嵌套（子）资源的 URL 模式？

Answer 1

这就是我解决的方法：

/**
 * Quarkus (or RESTEasy) doesn't make it easy to get the URI template including the
 * subresource. This custom class is used to track which subresource were invoked on
 * our way to the endpoint.
 */
@RequestScoped
public class SubresourcesTracked {

    private UriBuilder uriBuilder = null;

    public Optional<UriBuilder> getUriBuilder() {
        return Optional.ofNullable(uriBuilder);
    }

    public UriBuilder computeUriBuilderIfAbsent(Supplier<UriBuilder> supplier) {
        if (uriBuilder == null) {
            uriBuilder = supplier.get();
        }
        return uriBuilder;
    }
}

@InterceptorBinding
@Target({ ElementType.TYPE, ElementType.METHOD })
@Retention(value = RetentionPolicy.RUNTIME)
public @interface TrackingSubresource {
}

/**
 * Quarkus (or RESTEasy) doesn't make it easy to get the URI template including the
 * subresource. This custom class is used to track which subresource were invoked on
 * our way to the endpoint.
 */
@Interceptor
@TrackingSubresource
public class TrackingSubresourceInterceptor {

    @Inject
    SubresourcesTracked subresourcesTracked;

    @AroundInvoke
    public Object aroundInvoke(InvocationContext context) throws Exception {
        var method = context.getMethod();
        var uriBuilder = subresourcesTracked.computeUriBuilderIfAbsent(() -> {
            var resource = method.getDeclaringClass();
            Path pathAnnotationOnResource = resource.getAnnotation(Path.class);
            return UriBuilder.fromPath(pathAnnotationOnResource.value());
        });

        var pathAnnotationOnMethod = method.getAnnotation(Path.class);
        if (pathAnnotationOnMethod != null) {
            uriBuilder.path(pathAnnotationOnMethod.value());
        }

        return context.proceed();
    }
}

在请求过滤器中：

    @Inject
    SubresourcesTracked subresourcesTracked;

    private String getUri() {
        var uriBuilder = subresourcesTracked.getUriBuilder().map(UriBuilder::toTemplate).map(UriBuilder::fromPath).orElseGet(() -> UriBuilder.fromResource(resourceInfo.getResourceClass()));
        var path = resourceInfo.getResourceMethod().getAnnotation(Path.class);
        if (path != null) {
            uriBuilder = uriBuilder.path(resourceInfo.getResourceMethod());
        }
        return uriBuilder.toTemplate();
    }