多线程执行的3种场景示例代码

1.环境

语言：java

jdk版本：1.8

2.三种线程池场景使用

2.1 固定线程数执行，每个线程只执行1次，最后全部执行完毕后再进入最终方法处理收尾

java 复制代码

 public static void testEveryThreadFixedExecuteOne() {
        int threadNum = 4;
        ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(threadNum,
                threadNum, 0L, TimeUnit.MILLISECONDS,
                new LinkedBlockingQueue<Runnable>());
        CyclicBarrier cyclicBarrier = new CyclicBarrier(threadNum, () -> {
            //必须保证线程池的线程数与该类的值一致CyclicBarrier(int parties, Runnable barrierAction)parties一致
            // 线程池线程执行cyclicBarrier.await()会减一并阻塞线程等待cyclicBarrier所有操作完为0则进入该方法。
            // 所有执行完毕，执行这里面操作。
            System.out.println("全部线程执行结束了，这里可以处理最后收尾的逻辑");
        });
        for (int curentPageNum = 1; curentPageNum <= threadNum; curentPageNum++) {
            int finalCurentPageNum = curentPageNum;
            threadPoolExecutor.execute(() -> {
                try {
                    System.out.println("执行线程逻辑" + finalCurentPageNum);
                } catch (Exception exception) {
                    exception.printStackTrace();
                } finally {
                    try {
                        cyclicBarrier.await();
                    } catch (InterruptedException e) {
                        throw new RuntimeException(e);
                    } catch (BrokenBarrierException e) {
                        throw new RuntimeException(e);
                    }
                }
            });
        }
        //发送停止标志，线程全部执行完毕会直接关闭
        threadPoolExecutor.shutdown();
    }

2.2 线程池的线程可被重复利用，直到所有任务都执行完成

java 复制代码

public static void testThreadRepeatUse() {
        int threadNum = 4;
        int totalPageNum = 10;
        ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(threadNum,
                threadNum, 0L, TimeUnit.MILLISECONDS,
                new LinkedBlockingQueue<Runnable>());
        for (int curentPageNum = 1; curentPageNum <= totalPageNum; curentPageNum++) {
            int finalCurentPageNum = curentPageNum;
            threadPoolExecutor.execute(() -> {
                System.out.println("执行" + finalCurentPageNum + " " + Thread.currentThread().getName());
            });
        }
        //发送停止标志，线程全部执行完毕会直接关闭
        threadPoolExecutor.shutdown();
        try {
            boolean awaitLoop = true;
            //阻塞判断
            do {
                awaitLoop = !threadPoolExecutor.awaitTermination(2, TimeUnit.SECONDS);
            } while (awaitLoop);
        } catch (Exception exception) {
            exception.printStackTrace();
            threadPoolExecutor.shutdownNow();
        }
        System.out.println("线程都执行结束了，可以执行后续操作");
    }

2.3 线程池的每个线程只执行一件事，最终得到所有线程的执行结果

java 复制代码

public static void testGetAllThreadResult() throws Exception {
        int threadNum = 2;
        int execNum = 2;
        ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(threadNum,
                threadNum, 0L, TimeUnit.MILLISECONDS,
                new LinkedBlockingQueue<Runnable>());
        List<Callable<List<Map<String, String>>>> callableList = new ArrayList<>();
        final AtomicInteger atomicInteger = new AtomicInteger(0);
        for (int i = 0; i < execNum; i++) {
            callableList.add(new Callable<List<Map<String, String>>>() {
                @Override
                public List<Map<String, String>> call() throws Exception {
                    List<Map<String, String>> singleResultList = new ArrayList<>();
                    int automicInt = atomicInteger.incrementAndGet();
                    if (automicInt == 1) {
                        System.out.println("我做第一件事，扫地");
                        singleResultList = new ArrayList<>();
                        LinkedHashMap<String, String> sweepMap = new LinkedHashMap<>();
                        sweepMap.put("action", "sweep");
                        singleResultList.add(sweepMap);
                    } else if (automicInt == 2) {
                        System.out.println("我做第二件事，擦玻璃");
                        singleResultList = new ArrayList<>();
                        LinkedHashMap<String, String> wipeMap = new LinkedHashMap<>();
                        wipeMap.put("action", "wipe glass");
                        singleResultList.add(wipeMap);
                    }
                    return singleResultList;
                }
            });
        }
        //这里会去调用执行并等待线程池内的所有任务执行完毕
        List<Future<List<Map<String, String>>>> futureList = threadPoolExecutor.invokeAll(callableList,
                7, TimeUnit.SECONDS);
        //全部执行完毕获取每个线程的返回值
        List<Map<String,String>> resultList =new ArrayList<>();
        for (int i = 0; i <futureList.size() ; i++) {
            resultList.addAll(futureList.get(i).get());
        }
        System.out.println(String.format("全部执行完毕,结果集:%s",resultList));
        threadPoolExecutor.shutdown();
    }

以上就是3种场景使用，可进行参考。