Error(17) 解决多线程异步Feign调用请求头丢失问题

青旅半醒 2022-10-11 13:36 554阅读 0赞

###### 问题 ######

在微服务中，多线程异步+Feign调用会出现请求头丢失

###### 解决 ######

1.  在主线程中先获取请求头参数
2.  传入子线程中
3.  由子线程将请求头参数设置到上下文中
4.  最后在Feign转发处理中拿到子线程设置的上下文的请求头数据，转发到下游。

--------------------

获取上下文请求参数工具类

@Slf4j
    public class RequestContextUtil { 
    
        /** * 获取请求头数据 * * @return key->请求头名称 value->请求头值 * @author zhengqingya * @date 2021/6/30 9:39 下午 */
        public static Map<String, String> getHeaderMap() { 
            Map<String, String> headerMap = Maps.newLinkedHashMap();
            try { 
                ServletRequestAttributes requestAttributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
                if (requestAttributes == null) { 
                    return headerMap;
                }
                HttpServletRequest request = requestAttributes.getRequest();
                Enumeration<String> enumeration = request.getHeaderNames();
                while (enumeration.hasMoreElements()) { 
                    String key = enumeration.nextElement();
                    String value = request.getHeader(key);
                    headerMap.put(key, value);
                }
            } catch (Exception e) { 
                log.error("《RequestContextUtil》 获取请求头参数失败：", e);
            }
            return headerMap;
        }
    
    }

请求头上下文

@Slf4j
    public class RequestHeaderHandler { 
    
        public static final ThreadLocal<Map<String, String>> THREAD_LOCAL = new ThreadLocal<>();
    
        public static void setHeaderMap(Map<String, String> headerMap) { 
            THREAD_LOCAL.set(headerMap);
        }
    
        public static Map<String, String> getHeaderMap() { 
            return THREAD_LOCAL.get();
        }
    
        public static void remove() { 
            THREAD_LOCAL.remove();
        }
    
    }

Feign转发处理rpc调用传参

*/
    @Slf4j
    @Configuration
    public class FeignRequestInterceptor implements RequestInterceptor { 
    
        @Override
        @SneakyThrows
        public void apply(RequestTemplate requestTemplate) { 
            log.debug("========================== ↓↓↓↓↓↓ 《FeignRequestInterceptor》 Start... ↓↓↓↓↓↓ ==========================");
            Map<String, String> threadHeaderNameMap = RequestHeaderHandler.getHeaderMap();
            if (!CollectionUtils.isEmpty(threadHeaderNameMap)) { 
                threadHeaderNameMap.forEach((headerName, headerValue) -> { 
                    log.debug("《FeignRequestInterceptor》 多线程 headerName:【{}】 headerValue:【{}】", headerName, headerValue);
                    requestTemplate.header(headerName, headerValue);
                });
            }
            Map<String, String> headerMap = RequestContextUtil.getHeaderMap();
            headerMap.forEach((headerName, headerValue) -> { 
                log.debug("《FeignRequestInterceptor》 headerName:【{}】 headerValue:【{}】", headerName, headerValue);
                requestTemplate.header(headerName, headerValue);
            });
            log.debug("========================== ↑↑↑↑↑↑ 《FeignRequestInterceptor》 End... ↑↑↑↑↑↑ ==========================");
        }
    
    }

使用案例

@Slf4j
    @RestController
    @RequestMapping("/web/api/demo/test")
    @Api(tags = "测试api")
    @AllArgsConstructor
    public class RpcController extends BaseController { 
    
        private SystemTaskThread systemTaskThread;
    
        @GetMapping("getContextUserId")
        @ApiOperation("rpc调用测试 - Async")
        public void getContextUserId() { 
            Map<String, String> headerMap = RequestContextUtil.getHeaderMap();
            log.info("主线程请求头值: {}", headerMap.get("userId"));
            this.systemTaskThread.getRequestHeaderUserId(RequestContextUtil.getHeaderMap());
        }
    
    }
    
    @Slf4j
    @Component
    @AllArgsConstructor
    public class SystemTaskThread { 
    
        private ISystemClient systemClient;
    
        @SneakyThrows
        @Async(ThreadPoolConstant.SMALL_TOOLS_THREAD_POOL)
        public void getRequestHeaderUserId(Map<String, String> headerMap) { 
            RequestHeaderHandler.setHeaderMap(headerMap);
            log.info("子线程请求头值: {}", this.systemClient.getRequestHeaderUserId());
        }
    
    }

> 注：网上也有资料提到在主线程获取请求参数`RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();`传到子线程中，再重新赋值`RequestContextHolder.setRequestAttributes(requestAttributes);` 但是这种方式小编尝试无效，顺便记录在这里吧~

###### 本文案例demo源码 ######

[https://gitee.com/zhengqingya/small-tools][https_gitee.com_zhengqingya_small-tools]

--------------------

> 今日分享语句：  
> 在你失落时，千万不好失去对生活的信心;  
> 在你受挫折时，千万不好埋怨上天的不公;  
> 当你失败时，千万不好失去对成功的追求;  
> 人，总要经受住各种考验。

[https_gitee.com_zhengqingya_small-tools]: https://gitee.com/zhengqingya/small-tools