java中list.spliterator以及多线程使用问题 - 知否问答 - 万象云+社区

//这是controller public List<ConcurrentHashMap<String,Object>> test(@RequestBody List<ConcurrentHashMap<String,Object>> list){ final List<ConcurrentHashMap<String, Object>> concurrentHashMaps = Collections.synchronizedList(list); List<ConcurrentHashMap<String, Object>> ListMap = calculateService.getListMap(concurrentHashMaps); return ListMap; } //这是service // 线程池我设置了线程数为4 并且countDownLatch也为4 public List<ConcurrentHashMap<String, Object>> getListMap(List<ConcurrentHashMap<String, Object>> list) { // 将list四等分 Spliterator<ConcurrentHashMap<String, Object>> allList = list.spliterator(); Spliterator<ConcurrentHashMap<String, Object>> halfList = allList.trySplit(); Spliterator<ConcurrentHashMap<String, Object>> quarterAllList = allList.trySplit(); Spliterator<ConcurrentHashMap<String, Object>> quarterHalfList = halfList.trySplit(); ServletRequestAttributes servletRequestAttributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes(); RequestContextHolder.setRequestAttributes(servletRequestAttributes,true); //将分好的List放进线程池 List<Spliterator<ConcurrentHashMap<String, Object>>> spliterators = Arrays.asList(allList, halfList, quarterAllList, quarterHalfList); for (Spliterator<ConcurrentHashMap<String, Object>> spliterator : spliterators) { if (ObjectUtil.isNotNull(spliterator)){ executor.execute(new SelectTask(taxInfoMapper,countDownLatch,spliterator)); } } try { // 阻塞住主线程，等待任务完成 countDownLatch.await(); } catch (InterruptedException e) { e.printStackTrace(); } return list; } public class SelectTask implements Runnable { private TaxInfoMapper taxInfoMapper; private CountDownLatch countDownLatch; private Spliterator<ConcurrentHashMap<String, Object>> list; public SelectTask(TaxInfoMapper taxInfoMapper, CountDownLatch countDownLatch, Spliterator<ConcurrentHashMap<String, Object>> list) { this.taxInfoMapper = taxInfoMapper; this.countDownLatch = countDownLatch; this.list = list; } @Override public void run() { list.forEachRemaining(map -> { String taxNo = (String) map.get("taxNo"); String deptNo = (String) map.get("deptNo"); String month = (String) map.get("month"); List<String> idList = (List<String>) map.get("idList"); // 这里我传进来一个mapper然后查询出一个对象List List<TaxInfoBO> taxInfoBOS = taxInfoMapper.selectTaxInfoList(taxNo, deptNo, month, idList); // 然后将他放在原先的map中 map.put("taxInfoList",taxInfoBOS); countDownLatch.countDown(); }); } }

{ "taxNo": "123124", "month": "2019-12", "deptNo": "1", "idList":[ "310104198603042438", "130130198907243027", "330722199110014512", "362322198903110046", "330402198703161239", "33062119820508869X", "33262419880810002X", "371002199204038253" ] }, 返回结果应该有一个taxInfoList

// 创建一个线程池，包含5个线程 ExecutorService executor = Executors.newFixedThreadPool(5); // 创建一个计数器，用于记录当前线程访问的元素数量 AtomicInteger count = new AtomicInteger(0); // 使用spliterator()方法获取列表的可迭代对象的迭代器 List<Integer> iterator = list.spliterator(); // 创建一个线程池的执行器，每个线程负责访问一个元素并更新计数器 for (int i = 0; i < 5; i++) { executor.execute(() -> { // 获取当前迭代的下一个元素 int element = iterator.next(); // 更新计数器 count.incrementAndGet(); // 在这里执行一些操作，如打印元素或执行其他耗时操作 System.out.println("Element " + element + " accessed, count: " + count.get()); }); } // 关闭线程池 executor.shutdown(); // 等待所有线程完成 while (!executor.isTerminated()) { try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } // 打印所有的元素和计数器 System.out.println("Elements accessed: " + list.size() + ", count: " + count.get()); }

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