在微服务环境下，远程调用feign和异步线程存在请求数据丢失问题

一、无异步线程得情况下feign远程调用：

0、登录拦截器：

@Component
public class LoginUserInterceptor implements HandlerInterceptor {
    public static ThreadLocal<MemberResVo> loginUser = new ThreadLocal<>();
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {

        //获取登录用户的键
        MemberResVo attribute = (MemberResVo) request.getSession().getAttribute(AuthServerConstant.LONG_USER);
        if (attribute!=null){
            loginUser.set(attribute);
            return true;
        }else {
            request.getSession().setAttribute("msg","请先进行登录！");
            response.sendRedirect("http://auth.gulimall.com/login.html");
            return false;
        }
    }
}

1、问题示例图：

解决方法：

import feign.RequestInterceptor;
import feign.RequestTemplate;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.servlet.http.HttpServletRequest;

@Configuration
public class GuliFeignConfig {
    //fegin过滤器
    @Bean("requestInterceptor")
    public RequestInterceptor requestInterceptor() {
        return new RequestInterceptor() {
            public void apply(RequestTemplate template) {
                //上下文环境保持器,拿到刚进来这个请求包含的数据，而不会因为远程数据请求头被清除
                ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
                HttpServletRequest request = attributes.getRequest();//老的请求
                if (request != null) {
                    //同步老的请求头中的数据，这里是获取cookie
                    String cookie = request.getHeader("Cookie");
                    template.header("Cookie", cookie);
                }
            }
        };
    }
}

二、异步情况下丢失上下文问题：

① 在同一线程下进行远程调用，即一连串调用的情况下OrederService通过远程调用先查找adress信息，再查找cart信息，则仅需配置GuliFeignConfig就够了

② 由于采用的异步任务，所以101、102线程在自己的线程中调用登录拦截器interceptor，而其实只有在72号线程中登陆拦截器才进行放行（有请求头数据），这就导致101、102的request为null

解决方式（高亮部分）：从总线中获取request数据放入子线程中

@Service("orderService")
public class OrderServiceImpl extends ServiceImpl<OrderDao, OrderEntity> implements OrderService {
    @Autowired
    MemberFeignService memberFeignService;

    @Autowired
    CartFeginService cartFeginService;

    @Autowired
    ThreadPoolExecutor executor;

    @Autowired
    WmsFeignService wmsFeignService;

    /**
     * 订单确认页返回的数据
     * @return
     */
    @Override
    public OrderConfirmVo confirmOrder() throws ExecutionException, InterruptedException {
        OrderConfirmVo confirmVo = new OrderConfirmVo();
        MemberResVo memberResVo = LoginUserInterceptor.loginUser.get();
        //从主线程中获得所有request数据
        RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();

        CompletableFuture<Void> getAddressFuture = CompletableFuture.runAsync(() -> {
            //1、远程查询所有地址列表
            RequestContextHolder.setRequestAttributes(requestAttributes);
            List<MemberAddressVo> address = memberFeignService.getAddress(memberResVo.getId());

            confirmVo.setAddress(address);
        }, executor);

        //2、远程查询购物车所选的购物项,获得所有购物项数据
        CompletableFuture<Void> cartFuture = CompletableFuture.runAsync(() -> {
            //放入子线程中request数据
            RequestContextHolder.setRequestAttributes(requestAttributes);
            List<OrderItemVo> items = cartFeginService.getCurrentUserCartItems();
            confirmVo.setItem(items);
        }, executor).thenRunAsync(()->{
            RequestContextHolder.setRequestAttributes(requestAttributes);
            List<OrderItemVo> items = confirmVo.getItem();
            List<Long> collect = items.stream().map(item -> item.getSkuId()).collect(Collectors.toList());
            //远程调用查询是否有库存
            R hasStock = wmsFeignService.getSkusHasStock(collect);
            //形成一个List集合，获取所有物品是否有货的情况
            List<SkuStockVo> data = hasStock.getData(new TypeReference<List<SkuStockVo>>() {
            });
            if (data!=null){
                //收集起来，Map<Long,Boolean> stocks;
                Map<Long, Boolean> map = data.stream().collect(Collectors.toMap(SkuStockVo::getSkuId, SkuStockVo::getHasStock));
                confirmVo.setStocks(map);
            }
        },executor);
        //feign远程调用在调用之前会调用很多拦截器，因此远程调用会丢失很多请求头

        //3、查询用户积分
        Integer integration = memberResVo.getIntegration();
        confirmVo.setIntegration(integration);
        //其他数据自动计算

        CompletableFuture.allOf(getAddressFuture,cartFuture).get();
        return confirmVo;
    }

}