多線程並發查詢mysql數據庫中的數據

用10個一次拉2噸的卡車代替1個一次拉10噸的卡車。前提是有資源折騰，比如線程池，多核cpu,也要考慮線程的切換代價。把java服務器和數據庫服務器綜合利用起來，傳統的方式是java服務器發送一條指令給數據庫就坐等喝茶拿結果，數據庫累個半死才出結果，而且出力不討好，嫌干活慢，現在也要讓java服務器也要干點事，這樣大家都心里比較平衡點。

List<CompletableFuture<List<TimesAndAmount>>>  allStationsTimesAmount =
        inputParamArrayList.stream()
                .map(inputParam -> CompletableFuture.supplyAsync(() ->nonOilSalesAndPerCustomerTransactionDao.getTimesHoursInterval(inputParam), executorService))
                .collect(Collectors.toList());

List<List<TimesAndAmount>>  timesAmount = allStationsTimesAmount.stream()
        .map(CompletableFuture::join)
        .collect(Collectors.toList());

private List<String> getBarcodeList(String[] deptIds, String[] ids) {

    List<String> list = new ArrayList<>();
    List<String> list1 = new ArrayList<>();
    if (deptIds != null){
        list = Arrays.asList(deptIds);

        List<CompletableFuture<List<String>>>  allBarcodes =
                list.stream()
                        .map(inputParam -> CompletableFuture.supplyAsync(() ->nonOilSalesAndPerCustomerTransactionDao.getBarcodesBydeptid(inputParam), executorService))
                        .collect(Collectors.toList());

        List<List<String>>  listList = allBarcodes.stream()
                .map(CompletableFuture::join)
                .collect(Collectors.toList());

//List<List<String>> 轉換為List<String> ，使用flatMap

        list1 =
                listList.stream()
                        .flatMap(inner -> inner.stream()).collect(Collectors.toList());


    }

    if (ids != null){
        list1.addAll(Arrays.asList(ids));
    }

    return list1;

}