SpringCloud中分析講解Feign組件添加請求頭有哪些坑梳理

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);
}

提示錯誤:

java.lang.IllegalArgumentException: method GET must not have a request body.

分析

通過斷點debug發現feign發請求時把userInfo參數當成瞭requestBody來處理,而okhttp3會檢測get請求不允許有body(其他類型的請求哪怕不報錯,但因為不是設置到請求頭,依然不滿足需求)。

查閱官方文檔裡是通過Contract(Feign.Contract.Default)來解析註解的:

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.

從自動配置類找到使用的是spring cloud的SpringMvcContract(用來解析@RequestMapping相關的註解),而這個註解並不會處理解析上面列的註解

@Configuration
public class FeignClientsConfiguration {
	@Bean
	@ConditionalOnMissingBean
	public Contract feignContract(ConversionService feignConversionService) {
		return new SpringMvcContract(this.parameterProcessors, feignConversionService);
	}

解決

原因找到瞭:spring cloud使用瞭自己的SpringMvcContract來解析註解,導致默認的註解解析方式失效。 解決方案自然就是重新解析處理feign的註解,這裡通過自定義Contract繼承SpringMvcContract再把Feign.Contract.Default解析邏輯般過來即可(重載的方法是在SpringMvcContract基礎上做進一步解析,否則Feign對RequestMapping相關對註解解析會失效)

代碼如下(此處隻對@Headers、@Param重新做瞭解析):

#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的註解
        super.processAnnotationOnMethod(data, methodAnnotation, method);
        //解析feign的headers註解
        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);
    }

改完馬上進行新一頓的操作, 看請求日志已經設置成功,響應OK!:

請求: {"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":""}

響應 {"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"]}"}

feign官方鏈接

spring cloud feign 鏈接

(另一種實現請求頭的方式:實現RequestInterceptor,但是存在hystrix線程切換的坑)

到此這篇關於SpringCloud中分析講解Feign組件添加請求頭有哪些坑梳理的文章就介紹到這瞭,更多相關SpringCloud Feign組件內容請搜索WalkonNet以前的文章或繼續瀏覽下面的相關文章希望大傢以後多多支持WalkonNet!

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