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本篇內(nèi)容主要講解“FeignClient怎么共享Header及踩坑過(guò)程”,感興趣的朋友不妨來(lái)看看。本文介紹的方法操作簡(jiǎn)單快捷,實(shí)用性強(qiáng)。下面就讓小編來(lái)帶大家學(xué)習(xí)“FeignClient怎么共享Header及踩坑過(guò)程”吧!
我們?cè)谡{(diào)用feign的情況下,經(jīng)常需要用到客戶端所持有的header比如說(shuō)auth-token,我們需要將這些header傳遞下去
使用攔截器,在客戶端攔截feign的請(qǐng)求,并把所需要的header傳遞下去
代碼:
@Configuration public class FeignInterceptor implements RequestInterceptor { @Override public void apply(RequestTemplate requestTemplate) { Map<String,String> headers = getHeaders(getHttpServletRequest()); for(String headerName : headers.keySet()){ requestTemplate.header(headerName, getHeaders(getHttpServletRequest()).get(headerName)); } } private HttpServletRequest getHttpServletRequest() { try { return ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest(); } catch (Exception e) { e.printStackTrace(); return null; } } private Map<String, String> getHeaders(HttpServletRequest request) { Map<String, String> map = new LinkedHashMap<>(); Enumeration<String> enumeration = request.getHeaderNames(); while (enumeration.hasMoreElements()) { String key = enumeration.nextElement(); if(needThisHeader(key)){ String value = request.getHeader(key); map.put(key, value); } } return map; } private boolean needThisHeader(String headerName){ //todo:這里寫(xiě)你的邏輯,哪些header需要傳遞,千萬(wàn)不能把所有的header傳下去 return true; } }
@Configuration public class FeignSupportConfig { /** * feign請(qǐng)求攔截器 * * @return */ @Bean public RequestInterceptor requestInterceptor(){ return new FeignInterceptor(); } }
一定不能把所有的header都往下傳,這樣很可能會(huì)導(dǎo)致在調(diào)用feign的時(shí)候,請(qǐng)求類型混亂,應(yīng)該需要哪些header就穿哪些header
今天嘗試用feign去調(diào)用其他部門(mén)提供的一個(gè)HTTP接口,該接口要求在請(qǐng)求中設(shè)置一個(gè)username頭部,用于身份鑒權(quán)。
@FeignClient(name = "kafka-client", url = "http://kafka.xxx.com") public interface KafkaClient { @GetMapping(value = "/api/clusterManager/listTopics") @Headers( {"cache-control: no-cache", "username: wangyong@xxx.com"}) TopicsResponse listTopics(@RequestParam("clusterName") String clusterName, @RequestParam("clusterArea") String clusterArea); }
代碼寫(xiě)好好,嘗試去進(jìn)行訪問(wèn)
{ "timestamp": 1551768926170, "status": 500, "error": "Internal Server Error", "exception": "com.netflix.zuul.exception.ZuulException", "message": "pre:AuthAccessFilter" }
異常堆棧信息如下:
at feign.FeignException.errorStatus(FeignException.java:62)
at feign.codec.ErrorDecoder$Default.decode(ErrorDecoder.java:91)
at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:134)
at feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:76)
at feign.ReflectiveFeign$FeignInvocationHandler.invoke(ReflectiveFeign.java:103)
at com.sun.proxy.$Proxy147.listTopics(Unknown Source)
at com.yidian.data.exptmgr.controller.KafkaController.getKafkaTopics(KafkaController.java:35)
// 省略更多異常堆棧信息
于是我嘗試通過(guò)debug來(lái)找到問(wèn)題的根源,通過(guò)debug我發(fā)現(xiàn)feign會(huì)先將請(qǐng)求參數(shù)構(gòu)建成Request對(duì)象,request信息如下:
request
從圖中可看到,該Request實(shí)例的headers屬性為空,而Request又是根據(jù)RequestTemplate模板對(duì)象生成的,RequestTemplate實(shí)例信息如下:
RequestTemplate
到這里可以看出,問(wèn)題是出在RequestTemplate的構(gòu)建構(gòu)成中,于是我就去跟蹤RequestTemplate構(gòu)建的代碼,發(fā)現(xiàn)RequestTemplate是根據(jù)MethodMetadata構(gòu)建而成,而MethodMetadata就是對(duì)方法配置的抽象。
RequestTemplate template = resolve(argv, mutable, varBuilder); if (metadata.queryMapIndex() != null) { // add query map parameters after initial resolve so that they take // precedence over any predefined values template = addQueryMapQueryParameters(argv, template); } if (metadata.headerMapIndex() != null) { template = addHeaderMapHeaders(argv, template); }
從上述代碼可以看到,header的設(shè)置是由metadata的headerMapIndex 屬性決定的,那么,設(shè)置headerMapIndex的位置,必然就和Header的解析相關(guān),于是通過(guò)查看方法引用
private void parseHeaders(MethodMetadata md, Method method, RequestMapping annotation) { // TODO: only supports one header value per key if (annotation.headers() != null && annotation.headers().length > 0) { for (String header : annotation.headers()) { int index = header.indexOf('='); if (!header.contains("!=") && index >= 0) { md.template().header(resolve(header.substring(0, index)), resolve(header.substring(index + 1).trim())); } } } }
從代碼中我們可以清晰的看到,解析過(guò)程中是從@RequestMapping或其派生注解的header屬性中解析Header的,并且Header的key和value需要用“=”進(jìn)行分割。
于是我修改成下面的形式,
@GetMapping(value = "/api/clusterManager/listTopics", headers = {"cache-control=no-cache", "username=wangyong@xxx.com"}) TopicsResponse listTopics(@RequestParam("clusterName") String clusterName, @RequestParam("clusterArea") String clusterArea);
到此,相信大家對(duì)“FeignClient怎么共享Header及踩坑過(guò)程”有了更深的了解,不妨來(lái)實(shí)際操作一番吧!這里是億速云網(wǎng)站,更多相關(guān)內(nèi)容可以進(jìn)入相關(guān)頻道進(jìn)行查詢,關(guān)注我們,繼續(xù)學(xué)習(xí)!
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