过滤从 http 出站网关获得 200 状态的消息
filter messages that get 200 status from http outbound gateway
我有一个消息流，如果 GET HTTP 调用（通过 http:outbound-网关）的结果是 statusCode 200，我想 filter/drop 消息 - 即案例已经存在。换句话说，如果调用收到 404（未找到），流程应该继续。理想情况下，任何其他状态代码或异常都应该转到 errorHandler（就像现在一样）
我试过调用一个网关，该网关使用带有请求处理程序建议链的 http:outbound-gateway 链，我想我可以捕获 404，然后让事情继续，就好像它是不是错误，然后在 'filter' 中测试 statusCode 404。但是遇到了一些问题
- onFailureExpression 表达式未检测到 statusCode 404，日志显示 HttpClientErrorException，因此可能未捕获到异常？
- 我应该 return 从 onFailureExpression 得到什么值？ null 或 payload 或 #payload ？理想情况下，我希望 HTTP 调用之前的有效负载保持原样。
- 我需要 trapException true 吗？
- 惊讶没有更简单的方法吗？耻辱不能只在 http:outbound-gateway httpStatusCodes 上声明被允许并被视为正常。我不认为 errorChannel 和错误处理程序是正确的方法，因为如果出现 404 状态代码，我希望原始流程继续。因此，将需要的常规行为放入错误流中看起来很奇怪，并且已经有了更高级别的错误处理程序。
2020-11-24 10:46:45,060 [main] DEBUG org.springframework.web.client.RestTemplate - GET request for "http://localhost:9095/ccacase/V1/case/challenge/CHG123456789" resulted in 404 (Not Found); invoking error handler
2020-11-24 10:46:45,134 [main] DEBUG org.springframework.integration.channel.DirectChannel - postSend (sent=true) on channel 'getChallengeCaseChannel', message: GenericMessage [payload=uk.gov.voa.integration.ccacasecheck.json.CdbEvent@624b3544[id=22,eventType=MIGRATE_CHALLENGE_CASE,asstRef=<null>,ccaCaseRef=CHG123456789,assessmentStatus=<null>,settlementCode=<null>,eventDateTime=2020-11-23T12:05,uarn=<null>,sourceActivityId=<null>,activityAction=<null>,additionalProperties={}], headers={replyChannel=org.springframework.messaging.core.GenericMessagingTemplate$TemporaryReplyChannel@54f6b629, errorChannel=org.springframework.messaging.core.GenericMessagingTemplate$TemporaryReplyChannel@54f6b629, originalPayload=uk.gov.voa.integration.ccacasecheck.json.CdbEvent@624b3544[id=22,eventType=MIGRATE_CHALLENGE_CASE,asstRef=<null>,ccaCaseRef=CHG123456789,assessmentStatus=<null>,settlementCode=<null>,eventDateTime=2020-11-23T12:05,uarn=<null>,sourceActivityId=<null>,activityAction=<null>,additionalProperties={}], message_id=22, history=cdbEventsAMQPChannel,routeEventChain,migrateChallengeCaseEventChannel,migrateChallengeCaseEventChain,statusFlow,getChallengeCaseChannel, id=6d99e890-fc56-74a8-1187-fbc3457685c8, timestamp=1606214804576}]
2020-11-24 10:46:45,135 [main] DEBUG org.springframework.integration.handler.ExpressionEvaluatingMessageProcessor - SpEL Expression evaluation failed with Exception.org.springframework.web.client.HttpClientErrorException: 404 Not Found
Caused by: org.springframework.messaging.MessagingException: failed to transform message headers; nested exception is org.springframework.messaging.MessageHandlingException: Expression evaluation failed: @statusFlow.exchange(#root).headers[http_statusCode]; nested exception is org.springframework.web.client.HttpClientErrorException: 404 Not Found
at org.springframework.integration.transformer.HeaderEnricher.transform(HeaderEnricher.java:128)
at org.springframework.integration.transformer.MessageTransformingHandler.handleRequestMessage(MessageTransformingHandler.java:89)
... 72 more
Caused by: org.springframework.messaging.MessageHandlingException: Expression evaluation failed: @statusFlow.exchange(#root).headers[http_statusCode]; nested exception is org.springframework.web.client.HttpClientErrorException: 404 Not Found
at org.springframework.integration.util.AbstractExpressionEvaluator.evaluateExpression(AbstractExpressionEvaluator.java:143)
at org.springframework.integration.handler.ExpressionEvaluatingMessageProcessor.processMessage(ExpressionEvaluatingMessageProcessor.java:72)
at org.springframework.integration.transformer.support.ExpressionEvaluatingHeaderValueMessageProcessor.processMessage(ExpressionEvaluatingHeaderValueMessageProcessor.java:71)
at org.springframework.integration.transformer.HeaderEnricher.transform(HeaderEnricher.java:119)
... 73 more
Caused by: org.springframework.web.client.HttpClientErrorException: 404 Not Found
at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:91)
<int:chain id="migrateChallengeCaseEventChain" input-channel="migrateChallengeCaseEventChannel">
<int:header-enricher>
<int:header name="caseStatusCode" expression="@statusFlow.exchange(#root).headers[http_statusCode]" />
</int:header-enricher>
<!-- to check http_statusCode header and drop any message with found 200 statusCode -->
<int:filter ref="status200Filter"/>
<int:transformer ref="migrateChallengeCaseTransformer" />
<int:transformer ref="jsonValidationTransformer" />
<int:object-to-json-transformer object-mapper="springJacksonObjectMapper" />
<int:header-enricher>
<int:header name="contentType" value="application/json;charset=UTF-8" overwrite="true"/>
</int:header-enricher>
<int-amqp:outbound-channel-adapter
amqp-template="amqpTemplate" exchange-name="cdbEvents.exchange"
routing-key="migrateCdbCcaChallengeCase.request.queue.binding" />
</int:chain>
<int:gateway id="statusFlow" default-request-channel="getChallengeCaseChannel" />
<int:channel id="getChallengeCaseChannel" />
<!-- Call API to see if Case already exists, 200 status code we want to filter/drop message -->
<int:chain id="getChallengeCaseChain" input-channel="getChallengeCaseChannel">
<int-http:outbound-gateway id="httpOutboundGatewayChallengeCaseGet"
expected-response-type="java.lang.String"
http-method="GET" charset="UTF-8"
extract-request-payload="true"
request-factory="httpRequestFactory"
url="${mule.case.data.service.uri}/${case.challenge.subpath}/{ccaCaseRefValue}">
<int-http:uri-variable name="ccaCaseRefValue" expression="headers['originalPayload'].ccaCaseRef"/>
<int-http:request-handler-advice-chain>
<bean class="org.springframework.integration.handler.advice.ExpressionEvaluatingRequestHandlerAdvice">
<!-- If true, the result of evaluating the onFailureExpression will be returned as the result -->
<property name="returnFailureExpressionResult" value="true" />
<property name="onSuccessExpression" value="payload" />
<!-- If true, any exception will be caught and null returned. Default false -->
<property name="trapException" value="true" />
<!-- Set the expression to evaluate against the root message after a failed handler invocation. The exception is available as the variable #exception. Defaults to payload, if failureChannel is configured. -->
<property name="onFailureExpression" value="#exception.cause.statusCode == 404 ? payload : #exception"/>
<!-- Set the channel name to which to send the ErrorMessage after evaluating the failure expression. -->
<!-- <property name="failureChannel" ref="#headers['replyChannel']" /> -->
</bean>
</int-http:request-handler-advice-chain>
</int-http:outbound-gateway>
</int:chain>
使用的解决方案是实现自定义 ErrorHandler，它扩展默认值并覆盖 hasError
/**
* To be used with an 'int-http:outbound-gateway' to make a HTTP call and allow a statusCode 404
* response to be treated as normal (as well as a 200 statusCode).
* Normally a statusCode 404 would throw a
* org.springframework.web.client.HttpClientErrorException: 404 Not Found
* and expect the caller to deal with an error-channel.
* This allows processing to continue and subsequently test for a 404 response
* and route differently
*
*/
public class Allow404StatusCodeResponseHandler extends DefaultResponseErrorHandler {
/**
* OVERRIDEN
*
* Indicate whether the given response has any errors.
* <p>Implementations will typically inspect the
* {@link ClientHttpResponse#getStatusCode() HttpStatus} of the response.
* @param response the response to inspect
* @return {@code true} if the response indicates an error; {@code false} otherwise
* @throws IOException in case of I/O errors
*/
@Override
public boolean hasError(ClientHttpResponse response) throws IOException {
int rawStatusCode = response.getRawStatusCode();
return (rawStatusCode == 404 || rawStatusCode == 200) ? false : true; // 404 to be treated as normal and testable downstream
}
}
然后在 int-http:outbound-gateway
中设置
<int-http:outbound-gateway> 完全基于来自 Spring Web 的 RestTemplate。
那个带有 DefaultResponseErrorHandler，它确实将 4xx 视为错误 - 标准 HTTP 协议行为：https://www.restapitutorial.com/httpstatuscodes.html#.
另请参阅 class JavaDocs：
/**
* Spring's default implementation of the {@link ResponseErrorHandler} interface.
*
* <p>This error handler checks for the status code on the
* {@link ClientHttpResponse}. Any code in the 4xx or 5xx series is considered
* to be an error. This behavior can be changed by overriding
* {@link #hasError(HttpStatus)}. Unknown status codes will be ignored by
* {@link #hasError(ClientHttpResponse)}.
*
* <p>See {@link #handleError(ClientHttpResponse)} for more details on specific
* exception types.
*
* @author Arjen Poutsma
* @author Rossen Stoyanchev
* @author Juergen Hoeller
* @since 3.0
* @see RestTemplate#setErrorHandler
*/
public class DefaultResponseErrorHandler implements ResponseErrorHandler {
是的，您可以将任何自定义 ResponseErrorHandler 设置到 <int-http:outbound-gateway> 中以抑制默认行为，但我仍然认为最好处理 ExpressionEvaluatingRequestHandlerAdvice 来处理 HttpClientErrorException 及其 getStatusCode()。是的，您可能需要将 trapException 设置为 true 以避免 HttpClientErrorException 的 re-throw。是的，在失败流程中，您可以在请求之前访问原始消息。参见 ErrorMessage，MessagingException 作为其 payload 和 failedMessage 属性。
您可能会尝试使用更简单的您的 use-case 特定逻辑来实现您自己的 AbstractRequestHandlerAdvice：忽略 200 并适当地处理 404：https://docs.spring.io/spring-integration/docs/current/reference/html/messaging-endpoints.html#message-handler-advice-chain
状态代码 200 将出现在回复 AbstractIntegrationMessageBuilder 的 HttpHeaders.STATUS_CODE header 中，供您在建议中考虑。
我有一个消息流，如果 GET HTTP 调用（通过 http:outbound-网关）的结果是 statusCode 200，我想 filter/drop 消息 - 即案例已经存在。换句话说，如果调用收到 404（未找到），流程应该继续。理想情况下，任何其他状态代码或异常都应该转到 errorHandler（就像现在一样）
我试过调用一个网关，该网关使用带有请求处理程序建议链的 http:outbound-gateway 链，我想我可以捕获 404，然后让事情继续，就好像它是不是错误，然后在 'filter' 中测试 statusCode 404。但是遇到了一些问题
- onFailureExpression 表达式未检测到 statusCode 404，日志显示 HttpClientErrorException，因此可能未捕获到异常？
- 我应该 return 从 onFailureExpression 得到什么值？ null 或 payload 或 #payload ？理想情况下，我希望 HTTP 调用之前的有效负载保持原样。
- 我需要 trapException true 吗？
- 惊讶没有更简单的方法吗？耻辱不能只在 http:outbound-gateway httpStatusCodes 上声明被允许并被视为正常。我不认为 errorChannel 和错误处理程序是正确的方法，因为如果出现 404 状态代码，我希望原始流程继续。因此，将需要的常规行为放入错误流中看起来很奇怪，并且已经有了更高级别的错误处理程序。
2020-11-24 10:46:45,060 [main] DEBUG org.springframework.web.client.RestTemplate - GET request for "http://localhost:9095/ccacase/V1/case/challenge/CHG123456789" resulted in 404 (Not Found); invoking error handler
2020-11-24 10:46:45,134 [main] DEBUG org.springframework.integration.channel.DirectChannel - postSend (sent=true) on channel 'getChallengeCaseChannel', message: GenericMessage [payload=uk.gov.voa.integration.ccacasecheck.json.CdbEvent@624b3544[id=22,eventType=MIGRATE_CHALLENGE_CASE,asstRef=<null>,ccaCaseRef=CHG123456789,assessmentStatus=<null>,settlementCode=<null>,eventDateTime=2020-11-23T12:05,uarn=<null>,sourceActivityId=<null>,activityAction=<null>,additionalProperties={}], headers={replyChannel=org.springframework.messaging.core.GenericMessagingTemplate$TemporaryReplyChannel@54f6b629, errorChannel=org.springframework.messaging.core.GenericMessagingTemplate$TemporaryReplyChannel@54f6b629, originalPayload=uk.gov.voa.integration.ccacasecheck.json.CdbEvent@624b3544[id=22,eventType=MIGRATE_CHALLENGE_CASE,asstRef=<null>,ccaCaseRef=CHG123456789,assessmentStatus=<null>,settlementCode=<null>,eventDateTime=2020-11-23T12:05,uarn=<null>,sourceActivityId=<null>,activityAction=<null>,additionalProperties={}], message_id=22, history=cdbEventsAMQPChannel,routeEventChain,migrateChallengeCaseEventChannel,migrateChallengeCaseEventChain,statusFlow,getChallengeCaseChannel, id=6d99e890-fc56-74a8-1187-fbc3457685c8, timestamp=1606214804576}]
2020-11-24 10:46:45,135 [main] DEBUG org.springframework.integration.handler.ExpressionEvaluatingMessageProcessor - SpEL Expression evaluation failed with Exception.org.springframework.web.client.HttpClientErrorException: 404 Not Found
Caused by: org.springframework.messaging.MessagingException: failed to transform message headers; nested exception is org.springframework.messaging.MessageHandlingException: Expression evaluation failed: @statusFlow.exchange(#root).headers[http_statusCode]; nested exception is org.springframework.web.client.HttpClientErrorException: 404 Not Found
at org.springframework.integration.transformer.HeaderEnricher.transform(HeaderEnricher.java:128)
at org.springframework.integration.transformer.MessageTransformingHandler.handleRequestMessage(MessageTransformingHandler.java:89)
... 72 more
Caused by: org.springframework.messaging.MessageHandlingException: Expression evaluation failed: @statusFlow.exchange(#root).headers[http_statusCode]; nested exception is org.springframework.web.client.HttpClientErrorException: 404 Not Found
at org.springframework.integration.util.AbstractExpressionEvaluator.evaluateExpression(AbstractExpressionEvaluator.java:143)
at org.springframework.integration.handler.ExpressionEvaluatingMessageProcessor.processMessage(ExpressionEvaluatingMessageProcessor.java:72)
at org.springframework.integration.transformer.support.ExpressionEvaluatingHeaderValueMessageProcessor.processMessage(ExpressionEvaluatingHeaderValueMessageProcessor.java:71)
at org.springframework.integration.transformer.HeaderEnricher.transform(HeaderEnricher.java:119)
... 73 more
Caused by: org.springframework.web.client.HttpClientErrorException: 404 Not Found
at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:91)
<int:chain id="migrateChallengeCaseEventChain" input-channel="migrateChallengeCaseEventChannel">
<int:header-enricher>
<int:header name="caseStatusCode" expression="@statusFlow.exchange(#root).headers[http_statusCode]" />
</int:header-enricher>
<!-- to check http_statusCode header and drop any message with found 200 statusCode -->
<int:filter ref="status200Filter"/>
<int:transformer ref="migrateChallengeCaseTransformer" />
<int:transformer ref="jsonValidationTransformer" />
<int:object-to-json-transformer object-mapper="springJacksonObjectMapper" />
<int:header-enricher>
<int:header name="contentType" value="application/json;charset=UTF-8" overwrite="true"/>
</int:header-enricher>
<int-amqp:outbound-channel-adapter
amqp-template="amqpTemplate" exchange-name="cdbEvents.exchange"
routing-key="migrateCdbCcaChallengeCase.request.queue.binding" />
</int:chain>
<int:gateway id="statusFlow" default-request-channel="getChallengeCaseChannel" />
<int:channel id="getChallengeCaseChannel" />
<!-- Call API to see if Case already exists, 200 status code we want to filter/drop message -->
<int:chain id="getChallengeCaseChain" input-channel="getChallengeCaseChannel">
<int-http:outbound-gateway id="httpOutboundGatewayChallengeCaseGet"
expected-response-type="java.lang.String"
http-method="GET" charset="UTF-8"
extract-request-payload="true"
request-factory="httpRequestFactory"
url="${mule.case.data.service.uri}/${case.challenge.subpath}/{ccaCaseRefValue}">
<int-http:uri-variable name="ccaCaseRefValue" expression="headers['originalPayload'].ccaCaseRef"/>
<int-http:request-handler-advice-chain>
<bean class="org.springframework.integration.handler.advice.ExpressionEvaluatingRequestHandlerAdvice">
<!-- If true, the result of evaluating the onFailureExpression will be returned as the result -->
<property name="returnFailureExpressionResult" value="true" />
<property name="onSuccessExpression" value="payload" />
<!-- If true, any exception will be caught and null returned. Default false -->
<property name="trapException" value="true" />
<!-- Set the expression to evaluate against the root message after a failed handler invocation. The exception is available as the variable #exception. Defaults to payload, if failureChannel is configured. -->
<property name="onFailureExpression" value="#exception.cause.statusCode == 404 ? payload : #exception"/>
<!-- Set the channel name to which to send the ErrorMessage after evaluating the failure expression. -->
<!-- <property name="failureChannel" ref="#headers['replyChannel']" /> -->
</bean>
</int-http:request-handler-advice-chain>
</int-http:outbound-gateway>
</int:chain>
使用的解决方案是实现自定义 ErrorHandler，它扩展默认值并覆盖 hasError
/**
* To be used with an 'int-http:outbound-gateway' to make a HTTP call and allow a statusCode 404
* response to be treated as normal (as well as a 200 statusCode).
* Normally a statusCode 404 would throw a
* org.springframework.web.client.HttpClientErrorException: 404 Not Found
* and expect the caller to deal with an error-channel.
* This allows processing to continue and subsequently test for a 404 response
* and route differently
*
*/
public class Allow404StatusCodeResponseHandler extends DefaultResponseErrorHandler {
/**
* OVERRIDEN
*
* Indicate whether the given response has any errors.
* <p>Implementations will typically inspect the
* {@link ClientHttpResponse#getStatusCode() HttpStatus} of the response.
* @param response the response to inspect
* @return {@code true} if the response indicates an error; {@code false} otherwise
* @throws IOException in case of I/O errors
*/
@Override
public boolean hasError(ClientHttpResponse response) throws IOException {
int rawStatusCode = response.getRawStatusCode();
return (rawStatusCode == 404 || rawStatusCode == 200) ? false : true; // 404 to be treated as normal and testable downstream
}
}
然后在 int-http:outbound-gateway
中设置<int-http:outbound-gateway> 完全基于来自 Spring Web 的 RestTemplate。
那个带有 DefaultResponseErrorHandler，它确实将 4xx 视为错误 - 标准 HTTP 协议行为：https://www.restapitutorial.com/httpstatuscodes.html#.
另请参阅 class JavaDocs：
/**
* Spring's default implementation of the {@link ResponseErrorHandler} interface.
*
* <p>This error handler checks for the status code on the
* {@link ClientHttpResponse}. Any code in the 4xx or 5xx series is considered
* to be an error. This behavior can be changed by overriding
* {@link #hasError(HttpStatus)}. Unknown status codes will be ignored by
* {@link #hasError(ClientHttpResponse)}.
*
* <p>See {@link #handleError(ClientHttpResponse)} for more details on specific
* exception types.
*
* @author Arjen Poutsma
* @author Rossen Stoyanchev
* @author Juergen Hoeller
* @since 3.0
* @see RestTemplate#setErrorHandler
*/
public class DefaultResponseErrorHandler implements ResponseErrorHandler {
是的，您可以将任何自定义 ResponseErrorHandler 设置到 <int-http:outbound-gateway> 中以抑制默认行为，但我仍然认为最好处理 ExpressionEvaluatingRequestHandlerAdvice 来处理 HttpClientErrorException 及其 getStatusCode()。是的，您可能需要将 trapException 设置为 true 以避免 HttpClientErrorException 的 re-throw。是的，在失败流程中，您可以在请求之前访问原始消息。参见 ErrorMessage，MessagingException 作为其 payload 和 failedMessage 属性。
您可能会尝试使用更简单的您的 use-case 特定逻辑来实现您自己的 AbstractRequestHandlerAdvice：忽略 200 并适当地处理 404：https://docs.spring.io/spring-integration/docs/current/reference/html/messaging-endpoints.html#message-handler-advice-chain
状态代码 200 将出现在回复 AbstractIntegrationMessageBuilder 的 HttpHeaders.STATUS_CODE header 中，供您在建议中考虑。