SuperClass的泛型

Question

到目前为止，我已经创建了一个包含webclient和一些方法的类

    public class CustomWebClient<T> {
            
    private final WebClient webClient;
        
            public CustomWebClient(WebClient.Builder builder, ClientProperties properties) {
                String rootUrl = properties.getHttp().getRootUrl();
                webClient = builder
                        .baseUrl(rootUrl)
                        .defaultHeader(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE)
                        .defaultHeaders(httpHeaders -> httpHeaders.setAll(properties.getHeaders()))
                        .build();
            }

     public ​Mono<ResponseEntity<T>> setRequest(final String uri,
                                               ​final HttpMethod httpMethod,
                                               ​final Class<T> classToMap) {
     WebClient.RequestHeadersSpec<?> requestHeadersSpec = webClient.method(httpMethod).uri(uri);
     ​WebClient.ResponseSpec responseSpec = setRetrievingOptions(requestHeadersSpec);
       ​return setEntity(responseSpec, classToMap);
   
  }  

private WebClient.ResponseSpec setRetrievingOptions(final WebClient.RequestHeadersSpec<?> requestHeadersSpec) {
    return requestHeadersSpec.retrieve()
            .onStatus(HttpStatus::is4xxClientError,
                    clientResponse -> Mono.error(new ResponseStatusException(clientResponse.statusCode(), NOT_FOUND_MSG)))
            .onStatus(HttpStatus::is5xxServerError,
                    clientResponse -> Mono.error(new ResponseStatusException(clientResponse.statusCode(), INTERNAL_SERVER_ERROR_MSG)));
}

private Mono<ResponseEntity<T>> setEntity(final WebClient.ResponseSpec responseSpec, Class<T> classToMap) {
    return responseSpec.toEntity(classToMap);
}
 } 

然后将CustomWebClient注入到另一个类中，它是一个服务。

      public class ABCServiceImpl implements ABCService {
    
         private final CustomWebClient<? extends BaseResponse> customClient;
        
         private Mono<PageResponse> invokeGetPageFromABC(final String storeId, final String site, final MultiValueMap<String, String> queryParams) {
          Mono<ResponseEntity<PageResult>> responseEntityMono = customClient.setRequest(String.format(PAGE_ENDPOINT, site), HttpMethod.GET, queryParams, PageResult.class);
    
      return responseEntityMono.map(content ->
                    new ContentResponse(content.getStatusCode(), customWebClient.SUCCESS_MSG, createContent(content.getBody())));
        }

    private ContentDTO createContent(ContentResult contentResult){
        return Optional.ofNullable(contentResult)
                .filter(c -> Objects.nonNull(c.getContent()))
                .map(ContentResult::getContent)
                .orElse(new ContentDTO());
    }
}

此时，获取编译时错误，该错误为

Required type: Class <capture of ? extends BaseResponse>
Provided: Class <ContentResult>

这是我要传递的对象

public class ContentResult extends BaseResponse {

    private ContentDTO content;
}

因为我是新来的仿制药，所以我可能遗漏了一些东西，或者我没有完全理解。知道问题出在哪里了吗？

老实说，考虑到我实际上已经在注入customWebClient时指定了超类，所以我希望能够工作。

提前谢谢你！

Answer 1

我仔细看过了，我想我明白你想做什么了。我建议不要使用通配符("?")用这种方式。调用customClient.setRequest(..)时，编译器无法确定您有哪个版本的customClient (即BaseResponse的哪个子类)，因此当您试图传递参数化的Class对象(它看起来是PageResult.class)时，它会抛出一个错误

您可以通过将ABCServiceImpl转换为参数化类(即具有字段属性为private final CustomWebClient<T extends BaseResponse> customClient的ABCServiceImpl<T extends BaseResponse> )来修复此问题；

但我也不会这么做，因为看起来您的自定义客户端根本不需要参数化类型！

所以我建议这样做：

1. 从CustomWebClient中删除参数化类型。(即public class CustomWebClient而不是public class CustomWebClient)

public <T> ​Mono<ResponseEntity<T>> setRequest(..)使

1. 使public ​Mono<ResponseEntity<T>> setRequest(..)方法成为参数化方法：

1. 调用customWebClient上的方法如下所示：

customWebClient.<ContentResult>setRequest(ContentResult.class, ...etc);