java8 CompletableFuture使用示例

 /**
     * 并发请求接口  将数据整理到一起处理
     */
    @SuppressWarnings("unchecked")
    private void parallelReqBigData(SegmentUVArgs segmentUVArgs, Map<Integer, Tag> tagMap, AreaTag areaTag) {
        List<SegmentTagsReply> list = Collections.synchronizedList(new ArrayList<>(16));
        List<CompletableFuture<Void>> cfList = new ArrayList<>();

        //存储 请求uv的uv值
        Map<Integer, Integer> mapping = new HashMap<>();

        // 单独处理请求uv
        CompletableFuture<Void> cfUv =
            CompletableFuture.runAsync(() -> areaTag.setUv(DppUtils.processErrorAndReturnData(bdsClient.execute(segmentUVArgs)).getUv()), executorService);
        cfList.add(cfUv);

        Arrays.stream(TagCategoryEnum.values()).forEach(type -> {
           //异步请求
            CompletableFuture<Void> cf = CompletableFuture.runAsync(() -> {

                SegmentTagsArgs segmentTagsArgs = new SegmentTagsArgs();
                BeanUtils.copyProperties(segmentUVArgs, segmentTagsArgs);
                segmentTagsArgs.setTagCategory(type.getCode());
                SegmentTagsReply segmentTagsReply = DppUtils.processErrorAndReturnData(bdsClient.execute(segmentTagsArgs));
                list.add(segmentTagsReply);
            }, executorService);
            cfList.add(cf);
        });

        CompletableFuture<Void>[] completableFutures = cfList.toArray(new CompletableFuture[0]);
    //异步请求完成
        CompletableFuture<Void> c4 = 
CompletableFuture.allOf(completableFutures).whenComplete((ret, err) -> {
            if (err != null) {
                log.error("failed to select to big data", err);
                throw new OpenApiException(ErrorCode.COMMON_ERROR, ImmutableMap.of("err", err.toString()));
            } else {
                for (SegmentTagsReply segmentTagsReply : list) {
                    if (CollectionUtil.isNotEmpty(segmentTagsReply.getResidenceList())) {
                        areaTag.setResidenceList(segmentTagsReply.getResidenceList());
                    }
                    if (CollectionUtil.isNotEmpty(segmentTagsReply.getShoppingMallList())) {
                        areaTag.setShoppingMallList(segmentTagsReply.getShoppingMallList());
                    }
                    if (CollectionUtil.isNotEmpty(segmentTagsReply.getWorkPlaceList())) {
                        areaTag.setWorkPlaceList(segmentTagsReply.getWorkPlaceList());
                    }
                    mapping.putAll(segmentTagsReply.getTagCountMap());
                    mapping.forEach((k, v) -> {
                        Tag tag = tagMap.get(k);
                        if (null != tag) {
                            tag.setCount((long) v);
                        }
                    });
                }
            }
        });
        //　join()和get()方法都是阻塞调用它们的线程（通常为主线程）来获取CompletableFuture异步之后的返回值。
        c4.join();
    }