SpringCloud项目中Feign组件添加请求头所遇到的坑及解决
前言
在spring cloud的项目中用到了feign组件,简单配置过后即可完成请求的调用。
又因为有向请求添加Header头的需求,查阅了官方示例后,就觉得很简单,然后一顿操作之后调试报错...
按官方修改的示例:
#MidServerClient.java import feign.Param; import org.springframework.cloud.openfeign.FeignClient; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; @FeignClient(value = "edu-mid-server") public interface MidServerClient { @RequestMapping(value = "/test/header", method = RequestMethod.GET) @Headers({"userInfo:{userInfo}"}) Object headerTest(@Param("userInfo") String userInfo); }
提示错误:
java.lang.IllegalArgumentException: method GET must not have a request body.
分析
通过断点debug发现feign发请求时把userInfo参数当成了requestBody来处理,而okhttp3会检测get请求不允许有body(其他类型的请求哪怕不报错,但因为不是设置到请求头,依然不满足需求)。
查阅官方文档里是通过Contract(Feign.Contract.Default)来解析注解的:
Feign annotations define the Contract between the interface and how the underlying client should work. Feign's default contract defines the following annotations:
Annotation | Interface Target | Usage |
---|---|---|
@RequestLine | Method | Defines the HttpMethod and UriTemplate for request. Expressions, values wrapped in curly-braces {expression} are resolved using their corresponding @Param annotated parameters. |
@Param | Parameter | Defines a template variable, whose value will be used to resolve the corresponding template Expression, by name. |
@Headers | Method, Type | Defines a HeaderTemplate; a variation on a UriTemplate. that uses @Param annotated values to resolve the corresponding Expressions. When used on a Type, the template will be applied to every request. When used on a Method, the template will apply only to the annotated method. |
@QueryMap | Parameter | Defines a Map of name-value pairs, or POJO, to expand into a query string. |
@HeaderMap | Parameter | Defines a Map of name-value pairs, to expand into Http Headers |
@Body | Method | Defines a Template, similar to a UriTemplate and HeaderTemplate, that uses @Param annotated values to resolve the corresponding Expressions. |
从自动配置类找到使用的是spring cloud的SpringMvcContract(用来解析@RequestMapping相关的注解),而这个注解并不会处理解析上面列的注解
@Configuration public class FeignClientsConfiguration { ··· @Bean @ConditionalOnMissingBean public Contract feignContract(ConversionService feignConversionService) { return new SpringMvcContract(this.parameterProcessors, feignConversionService); } ···
解决
原因找到了
spring cloud使用了自己的SpringMvcContract来解析注解,导致默认的注解解析方式失效。
解决方案自然就是重新解析处理feign的注解,这里通过自定义Contract继承SpringMvcContract再把Feign.Contract.Default解析逻辑般过来即可(重载的方法是在SpringMvcContract基础上做进一步解析,否则Feign对RequestMapping相关对注解解析会失效)
代码如下(此处只对@Headers、@Param重新做了解析):
#FeignCustomContract.java import feign.Headers; import feign.MethodMetadata; import feign.Param; import org.springframework.cloud.openfeign.AnnotatedParameterProcessor; import org.springframework.cloud.openfeign.support.SpringMvcContract; import org.springframework.core.convert.ConversionService; import java.lang.annotation.Annotation; import java.lang.reflect.Method; import java.util.*; import static feign.Util.checkState; import static feign.Util.emptyToNull; public class FeignCustomContract extends SpringMvcContract { public FeignCustomContract(List<AnnotatedParameterProcessor> annotatedParameterProcessors, ConversionService conversionService) { super(annotatedParameterProcessors, conversionService); } @Override protected void processAnnotationOnMethod(MethodMetadata data, Annotation methodAnnotation, Method method) { //解析mvc的注解 super.processAnnotationOnMethod(data, methodAnnotation, method); //解析feign的headers注解 Class<? extends Annotation> annotationType = methodAnnotation.annotationType(); if (annotationType == Headers.class) { String[] headersOnMethod = Headers.class.cast(methodAnnotation).value(); checkState(headersOnMethod.length > 0, "Headers annotation was empty on method %s.", method.getName()); data.template().headers(toMap(headersOnMethod)); } } @Override protected boolean processAnnotationsOnParameter(MethodMetadata data, Annotation[] annotations, int paramIndex) { boolean isMvcHttpAnnotation = super.processAnnotationsOnParameter(data, annotations, paramIndex); boolean isFeignHttpAnnotation = false; for (Annotation annotation : annotations) { Class<? extends Annotation> annotationType = annotation.annotationType(); if (annotationType == Param.class) { Param paramAnnotation = (Param) annotation; String name = paramAnnotation.value(); checkState(emptyToNull(name) != null, "Param annotation was empty on param %s.", paramIndex); nameParam(data, name, paramIndex); isFeignHttpAnnotation = true; if (!data.template().hasRequestVariable(name)) { data.formParams().add(name); } } } return isMvcHttpAnnotation || isFeignHttpAnnotation; } private static Map<String, Collection<String>> toMap(String[] input) { Map<String, Collection<String>> result = new LinkedHashMap<String, Collection<String>>(input.length); for (String header : input) { int colon = header.indexOf(':'); String name = header.substring(0, colon); if (!result.containsKey(name)) { result.put(name, new ArrayList<String>(1)); } result.get(name).add(header.substring(colon + 1).trim()); } return result; } }
#FeignCustomConfiguration.java import feign.Contract; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty; import org.springframework.cloud.openfeign.AnnotatedParameterProcessor; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.core.convert.ConversionService; import java.util.ArrayList; import java.util.List; @Configuration public class FeignCustomConfiguration { ··· @Autowired(required = false) private List<AnnotatedParameterProcessor> parameterProcessors = new ArrayList<>(); @Bean @ConditionalOnProperty(name = "feign.feign-custom-contract", havingValue = "true", matchIfMissing = true) public Contract feignContract(ConversionService feignConversionService) { return new FeignCustomContract(this.parameterProcessors, feignConversionService); } ···
改完马上进行新一顿的操作, 看请求日志已经设置成功,响应OK!:
请求:{"type":"OKHTTP_REQ","uri":"/test/header","httpMethod":"GET","header":"{"accept":["/"],"userinfo":["{"userId":"sssss","phone":"13544445678],"x-b3-parentspanid":["e49c55484f6c19af"],"x-b3-sampled":["0"],"x-b3-spanid":["1d131b4ccd08d964"],"x-b3-traceid":["9405ce71a13d8289"]}","param":""}
响应{"type":"OKHTTP_RESP","uri":"/test/header","respStatus":0,"status":200,"time":5,"header":"{"cache-control":["no-cache,no-store,max-age=0,must-revalidate"],"connection":["keep-alive"],"content-length":["191"],"content-type":["application/json;charset=UTF-8"],"date":["Fri,11Oct201913:02:41GMT"],"expires":["0"],"pragma":["no-cache"],"x-content-type-options":["nosniff"],"x-frame-options":["DENY"],"x-xss-protection":["1;mode=block"]}"}
(另一种实现请求头的方式:实现RequestInterceptor,但是存在hystrix线程切换的坑)
总结
以上为个人经验,希望能给大家一个参考,也希望大家多多支持脚本之家。
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