解决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_Java教程

一、无异步线程得情况下feign远程调用：

1、登录拦截器：

				?

									@Component

									public class LoginUserInterceptor implements HandlerInterceptor {

									    public static ThreadLocal&lt;MemberResVo&gt; loginUser = new ThreadLocal&lt;&gt;();

									    @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;

									        }

									    }

									}

2.问题示例图：

解决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

3.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：

解决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

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

				?

									RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes()

				?

									@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;

									    }

									}