由于我使用ResponseEntity<T>作为我的FeignClient方法的返回值，我希望它返回一个具有400状态的ResponseEntity，如果它是服务器返回的内容。但它会抛出FeignException。
如何从FeignClient获取正确的ResponseEntity而不是Exception？
这是我的FeignClient：
@FeignClient(value = "uaa", configuration = OauthFeignClient.Conf.class)
public interface OauthFeignClient {
@RequestMapping(
value = "/oauth/token",
method = RequestMethod.POST,
consumes = MULTIPART_FORM_DATA_VALUE,
produces = APPLICATION_JSON_VALUE)
ResponseEntity<OauthTokenResponse> token(Map<String, ?> formParams);
class Conf {
@Value("${oauth.client.password}")
String oauthClientPassword;
@Bean
public Encoder feignFormEncoder() {
return new SpringFormEncoder();
}
@Bean
public Contract feignContract() {
return new SpringMvcContract();
}
@Bean
public BasicAuthRequestInterceptor basicAuthRequestInterceptor() {
return new BasicAuthRequestInterceptor("web-client", oauthClientPassword);
}
}
}
以及我如何使用它：
@PostMapping("/login")
public ResponseEntity<LoginTokenPair> getTokens(@RequestBody @Valid LoginRequest userCredentials) {
Map<String, String> formData = new HashMap<>();
ResponseEntity<OauthTokenResponse> response = oauthFeignClient.token(formData);
//code never reached if contacted service returns a 400
...
}
答案 0 :(得分：2)
顺便说一下，我在工作之前给出的解决方案，但我最初的意图是坏主意：错误是一个错误，不应该在名义流程上处理。抛出异常，就像Feign那样，并用@ExceptionHandler处理它是一个更好的方式进入Spring MVC世界。
所以有两个解决方案：
@ExceptionHandler FeignException
FeignClient配置ErrorDecoder，以便在您的业务层知道的异常中转换错误（并且已经提供@ExceptionHandler）我更喜欢第二种解决方案，因为收到的错误消息结构可能会从客户端更改为另一种，因此您可以通过每客户端错误解码从这些错误中提取更精细的数据。
FeignClient with conf （抱歉由于假装形式引入的噪音）
@FeignClient(value = "uaa", configuration = OauthFeignClient.Config.class)
public interface OauthFeignClient {
@RequestMapping(
value = "/oauth/token",
method = RequestMethod.POST,
consumes = MULTIPART_FORM_DATA_VALUE,
produces = APPLICATION_JSON_VALUE)
DefaultOAuth2AccessToken token(Map<String, ?> formParams);
@Configuration
class Config {
@Value("${oauth.client.password}")
String oauthClientPassword;
@Autowired
private ObjectFactory<HttpMessageConverters> messageConverters;
@Bean
public Encoder feignFormEncoder() {
return new SpringFormEncoder(new SpringEncoder(messageConverters));
}
@Bean
public Decoder springDecoder() {
return new ResponseEntityDecoder(new SpringDecoder(messageConverters));
}
@Bean
public Contract feignContract() {
return new SpringMvcContract();
}
@Bean
public BasicAuthRequestInterceptor basicAuthRequestInterceptor() {
return new BasicAuthRequestInterceptor("web-client", oauthClientPassword);
}
@Bean
public ErrorDecoder uaaErrorDecoder(Decoder decoder) {
return (methodKey, response) -> {
try {
OAuth2Exception uaaException = (OAuth2Exception) decoder.decode(response, OAuth2Exception.class);
return new SroException(
uaaException.getHttpErrorCode(),
uaaException.getOAuth2ErrorCode(),
Arrays.asList(uaaException.getSummary()));
} catch (Exception e) {
return new SroException(
response.status(),
"Authorization server responded with " + response.status() + " but failed to parse error payload",
Arrays.asList(e.getMessage()));
}
};
}
}
}
常见业务例外
public class SroException extends RuntimeException implements Serializable {
public final int status;
public final List<String> errors;
public SroException(final int status, final String message, final Collection<String> errors) {
super(message);
this.status = status;
this.errors = Collections.unmodifiableList(new ArrayList<>(errors));
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (!(o instanceof SroException)) return false;
SroException sroException = (SroException) o;
return status == sroException.status &&
Objects.equals(super.getMessage(), sroException.getMessage()) &&
Objects.equals(errors, sroException.errors);
}
@Override
public int hashCode() {
return Objects.hash(status, super.getMessage(), errors);
}
}
错误处理程序（从ResponseEntityExceptionHandler扩展名中提取）
@ExceptionHandler({SroException.class})
public ResponseEntity<Object> handleSroException(SroException ex) {
return new SroError(ex).toResponse();
}
错误回复DTO
@XmlRootElement
public class SroError implements Serializable {
public final int status;
public final String message;
public final List<String> errors;
public SroError(final int status, final String message, final Collection<String> errors) {
this.status = status;
this.message = message;
this.errors = Collections.unmodifiableList(new ArrayList<>(errors));
}
public SroError(final SroException e) {
this.status = e.status;
this.message = e.getMessage();
this.errors = Collections.unmodifiableList(e.errors);
}
protected SroError() {
this.status = -1;
this.message = null;
this.errors = null;
}
public ResponseEntity<Object> toResponse() {
return new ResponseEntity(this, HttpStatus.valueOf(this.status));
}
public ResponseEntity<Object> toResponse(HttpHeaders headers) {
return new ResponseEntity(this, headers, HttpStatus.valueOf(this.status));
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (!(o instanceof SroError)) return false;
SroError sroException = (SroError) o;
return status == sroException.status &&
Objects.equals(message, sroException.message) &&
Objects.equals(errors, sroException.errors);
}
@Override
public int hashCode() {
return Objects.hash(status, message, errors);
}
}
假设客户端使用，请注意@ControllerAdvice＆amp;和@ExceptionHandler({SroException.class})＆amp; @RestController
@RequestMapping("/uaa")
public class AuthenticationController {
private static final BearerToken REVOCATION_TOKEN = new BearerToken("", 0L);
private final OauthFeignClient oauthFeignClient;
private final int refreshTokenValidity;
@Autowired
public AuthenticationController(
OauthFeignClient oauthFeignClient,
@Value("${oauth.ttl.refresh-token}") int refreshTokenValidity) {
this.oauthFeignClient = oauthFeignClient;
this.refreshTokenValidity = refreshTokenValidity;
}
@PostMapping("/login")
public ResponseEntity<LoginTokenPair> getTokens(@RequestBody @Valid LoginRequest userCredentials) {
Map<String, String> formData = new HashMap<>();
formData.put("grant_type", "password");
formData.put("client_id", "web-client");
formData.put("username", userCredentials.username);
formData.put("password", userCredentials.password);
formData.put("scope", "openid");
DefaultOAuth2AccessToken response = oauthFeignClient.token(formData);
return ResponseEntity.ok(new LoginTokenPair(
new BearerToken(response.getValue(), response.getExpiresIn()),
new BearerToken(response.getRefreshToken().getValue(), refreshTokenValidity)));
}
@PostMapping("/logout")
public ResponseEntity<LoginTokenPair> revokeTokens() {
return ResponseEntity
.ok(new LoginTokenPair(REVOCATION_TOKEN, REVOCATION_TOKEN));
}
@PostMapping("/refresh")
public ResponseEntity<BearerToken> refreshToken(@RequestHeader("refresh_token") String refresh_token) {
Map<String, String> formData = new HashMap<>();
formData.put("grant_type", "refresh_token");
formData.put("client_id", "web-client");
formData.put("refresh_token", refresh_token);
formData.put("scope", "openid");
DefaultOAuth2AccessToken response = oauthFeignClient.token(formData);
return ResponseEntity.ok(new BearerToken(response.getValue(), response.getExpiresIn()));
}
}
library(dplyr)
filter(df, any(NUM > 2) & any(NUM < -2))
# A tibble: 16 x 3
# Groups: id, grp [2]
id grp NUM
<int> <chr> <dbl>
1 0 01 -4.00
2 0 01 -3.00
3 0 01 -2.00
4 0 01 -1.00
5 0 01 1.00
6 0 01 2.00
7 0 01 3.00
8 0 01 4.00
9 1 02 -3.00
10 1 02 -2.00
11 1 02 -1.00
12 1 02 1.00
13 1 02 2.00
14 1 02 3.00
15 1 02 4.00
16 1 02 5.00
答案 1 :(得分：1)
所以，看一下源代码，它认为只有解决方案实际上是使用feign.Response作为FeignClient方法的返回类型，并用new ObjectMapper().readValue(response.body().asReader(), clazz)之类的方式手动解码正文（保护2xx状态为当然，因为对于错误状态，身体很可能是错误描述而不是有效的有效载荷;）。
即使状态不在2xx范围内，也可以提取和转发状态，标题，正文等。
编辑： 这是一种转发状态，标题和映射JSON正文的方法（如果可能）：
public static class JsonFeignResponseHelper {
private final ObjectMapper json = new ObjectMapper();
public <T> Optional<T> decode(Response response, Class<T> clazz) {
if(response.status() >= 200 && response.status() < 300) {
try {
return Optional.of(json.readValue(response.body().asReader(), clazz));
} catch(IOException e) {
return Optional.empty();
}
} else {
return Optional.empty();
}
}
public <T, U> ResponseEntity<U> toResponseEntity(Response response, Class<T> clazz, Function<? super T, ? extends U> mapper) {
Optional<U> payload = decode(response, clazz).map(mapper);
return new ResponseEntity(
payload.orElse(null),//didn't find a way to feed body with original content if payload is empty
convertHeaders(response.headers()),
HttpStatus.valueOf(response.status()));
}
public MultiValueMap<String, String> convertHeaders(Map<String, Collection<String>> responseHeaders) {
MultiValueMap<String, String> responseEntityHeaders = new LinkedMultiValueMap<>();
responseHeaders.entrySet().stream().forEach(e ->
responseEntityHeaders.put(e.getKey(), new ArrayList<>(e.getValue())));
return responseEntityHeaders;
}
}
可以使用如下：
@PostMapping("/login")
public ResponseEntity<LoginTokenPair> getTokens(@RequestBody @Valid LoginRequest userCredentials) throws IOException {
Response response = oauthFeignClient.token();
return feignHelper.toResponseEntity(
response,
OauthTokenResponse.class,
oauthTokenResponse -> new LoginTokenPair(
new BearerToken(oauthTokenResponse.access_token, oauthTokenResponse.expires_in),
new BearerToken(oauthTokenResponse.refresh_token, refreshTokenValidity)));
}
这会保存标头和状态代码，但会丢失错误消息：/