java使用Future实现多线程执行和结果聚合

• • 场景
  • 解决

• 网站智能问答场景，需要对多个分类查询，结果聚合展示
• 由于每种分类都有自己的业务逻辑，有的需要查询数据库中间库，有的需要查询elasticsearch搜索引擎，有的需要调用第三方接口，数据查询要分开进行，没法一次查询搞定
• 实际上这几个查询不相关，可以同时进行，现在串行，使该场景下，智能问答返回较慢

• 最简单的逻辑，肯定就是java多线程，将串行改为并行
• 这样查询返回时间，就取决于最慢的一个查询，返回时间大大缩短
• 页面返回一般要求三秒内，实际项目上我们要求1秒内返回，多线程解决了这个问题
• 下面上代码，部分截取

	@Autowired
    private ThreadPoolTaskExecutor taskExecutor;

// 新闻查询
            SolrPageQueryVO newsQueryVO = new SolrPageQueryVO();
            BeanUtil.copyProperties(vo, newsQueryVO);
            newsQueryVO.setAllSite(vo.getAllSite());
            newsQueryVO.setTypeCode(SolrPageQueryVO.TypeCode.articleNews.toString().concat(",")
                    .concat(SolrPageQueryVO.TypeCode.pictureNews.toString())
                    .concat(",").concat(SolrPageQueryVO.TypeCode.videoNews.toString()));
            Future newsFuture = taskExecutor.submit(()->selectForAsk(map, sumMap, newsQueryVO, "news", context));

            //网上服务
            Future workGuideFuture = taskExecutor.submit(()->selectForAsk(map, sumMap, vo, "workGuide", context));

            //留言
            SolrPageQueryVO messageBoardQueryVO = new SolrPageQueryVO();
            BeanUtil.copyProperties(vo, messageBoardQueryVO);
            messageBoardQueryVO.setAllSite(vo.getAllSite());
            messageBoardQueryVO.setTypeCode(SolrPageQueryVO.TypeCode.messageBoard.toString());
            Future messageBoardFuture = taskExecutor.submit(()->selectForAsk(map, sumMap, messageBoardQueryVO, "messageBoard", context));

            //信息公开（isAllSite为true时，搜索所有集合，不区分集合和站点，只根据dn搜索，有区分需要的项目可以重写SearchEsServiceImpl类）
            SolrPageQueryVO publicContentQueryVO = new SolrPageQueryVO();
            BeanUtil.copyProperties(vo, publicContentQueryVO);
            publicContentQueryVO.setAllSite(vo.getAllSite());
            publicContentQueryVO.setTypeCode(SolrPageQueryVO.TypeCode.public_content.toString());
            Future publicContentFuture = taskExecutor.submit(()->selectForAsk(map, sumMap, publicContentQueryVO, "public_content", context));


            //问答知识库（isAllSite为true时，搜索所有集合，不区分集合和站点，有区分需要的项目可以重写或传false）
            SolrPageQueryVO knowledgebaseQueryVO = new SolrPageQueryVO();
            BeanUtil.copyProperties(vo, knowledgebaseQueryVO);
            knowledgebaseQueryVO.setAllSite(vo.getAllSite());
            knowledgebaseQueryVO.setTypeCode(SolrPageQueryVO.TypeCode.knowledgebase.toString());
            Future knowledgebaseFuture = taskExecutor.submit(()->selectForAsk(map, sumMap, knowledgebaseQueryVO, "knowledgebase", context));

            try {
                knowledgebaseFuture.get();
            } catch (Exception e) {
                e.printStackTrace();
            }
            try {
                messageBoardFuture.get();
            } catch (Exception e) {
                e.printStackTrace();
            }
            try {
                newsFuture.get();
            } catch (Exception e) {
                e.printStackTrace();
            }
            try {
                publicContentFuture.get();
            } catch (Exception e) {
                e.printStackTrace();
            }
            try {
                workGuideFuture.get();
            } catch (Exception e) {
                e.printStackTrace();
            }

            tabcount = sumMap.values().size();
            map.put("tabcount", tabcount);
            map.put("numMap", sumMap);

 private void selectForAsk(Map map, Map sumMap, SolrPageQueryVO vo, String type, Context context) {
        if ("news".equals(type)) {
            try {
                // do something
            } catch (Exception e) {
                e.printStackTrace();
            }
        } else if ("workGuide".equals(type)) {
            try {
                //网上办事查询调用接口
               // do something
            } catch (Exception e) {
                e.printStackTrace();
            }
        } else if ("messageBoard".equals(type)) {
            try {
                // do something
            } catch (Exception e) {
                e.printStackTrace();
            }
        } else if ("public_content".equals(type)) {
            try {
                Long queryCount = SearchQueryHolder.queryCount(vo);
                // do something
            } catch (Exception e) {
                e.printStackTrace();
            }
        } else if ("knowledgebase".equals(type)) {
            try {
                // do something
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }