i am using spring boot to call a openfeign client and from the Response of that feign i need to extract some header values.how can i do that.
can anybody help please.
just help me wheather we can do that or not!

我正在使用Spring Boot调用一个OpenFeign客户端，从该伪装的响应中我需要提取一些头值。我该如何做到这一点。有谁能帮帮忙。帮帮我，不管我们能不能做到这一点！

Yes, you can do that. With Feign, we usually declare our interface with the method returning our class and Feign will automatically de-serialise the response from JSON into our POJO.

是的，你可以做到的。使用Feign时，我们通常使用返回类的方法声明接口，Feign会自动将来自JSON的响应反序列化到POJO中。

Here is the interface (operation):

下面是接口(操作)：

@FeignClient(name = "library-book-service")
@RequestMapping("books")
public interface BookClient {

    @GetMapping
    public List<Book> getBooks(
        @RequestParam("page") Optional<Integer> pageNum,
        @RequestParam("size") Optional<Integer> pageSize,
        @RequestParam("reader") Optional<Long> readerId);
}

And then you can use the feign client like this:

然后您可以像这样使用Feign客户端：

@Service
@RequiredArgsConstructor
public class BookService {
    private final @NonNull BookClient bookClient;

    public List<Book> retrieveBooks(
        Optional<Integer> pageNum, 
        Optional<Integer> pageSize, 
        Optional<Long> readerId) {

            return bookClient.getBooks(pageNum, pageSize, readerId);
    }

However, in order to have access to the response headers, you need to declare your methods to return feign.Response.

但是，为了能够访问响应头，您需要声明您的方法以返回feign.Response。

import feign.Response;

@FeignClient(name = "library-book-service")
@RequestMapping("books")
public interface BookClient {

    @GetMapping
    public Response getBooks(
        @RequestParam("page") Optional<Integer> pageNum,
        @RequestParam("size") Optional<Integer> pageSize,
        @RequestParam("reader") Optional<Long> readerId);
}

This way you can have access to the response body and headers:

这样，您就可以访问响应正文和标头：

@Service
@RequiredArgsConstructor
public class BookService {
    private final @NonNull BookClient bookClient;
    private final @NonNull ObjectMapper objectMapper;

    public List<Book> retrieveBooks(
        Optional<Integer> pageNum, 
        Optional<Integer> pageSize, 
        Optional<Long> readerId) {

          var response = bookClient.getBooks(pageNum, pageSize, readerId);
          if (response == null) {
            return Collections.emptyList();
          }

          // retrieve body
          var books = objectMapper.readValue(
            new BufferedReader(new InputStreamReader(response.body().asInputStream(), StandardCharsets.UTF_8)),
            new TypeReference<List<Book>>(){});

          // retrieve headers
          Map<String, Collection<String>> headers = response.headers();
          // ... do whatever you need with the headers

          return books;
    }

You can use import feign.Response as a response like:

您可以使用导入feign.Response作为响应，如下所示：

@PostMapping("/test")
Response test(@RequestBody TestRequest testRequest);

then you can reach http header

然后您可以访问http标头。

response.headers().get(HEADER_NAME).toString();

if you want get body in this case you have to some json-string manipulation by use response.body() this page may help you for this

在这种情况下，如果您想要获取Body，则必须使用Response.Body()进行一些json字符串操作。此页面可能会为您提供帮助

Presumably you want to retrieve both the (deserialized) response body as well as the response headers. In that case, returning a ResponseEntity is ideal because it includes both.

假设您希望检索(反序列化的)响应正文和响应头。在这种情况下，返回ResponseEntity是理想的，因为它包括两者。

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import static org.springframework.http.MediaType.APPLICATION_JSON_VALUE;

@FeignClient(name = "HttpStatusClient", url = "https://httpstat.us")
interface HttpStatusClient {
    record HttpStatus(int code, String description){}

    @GetMapping(path = "/200", produces = APPLICATION_JSON_VALUE)
    ResponseEntity<HttpStatus> twoHundred();
}