import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.atomic.AtomicInteger;

public class IncrTest {
    public static void concurrenceTest() {
        /**
         * 模擬高並發情況代碼
         */
        final
 
 AtomicInteger atomicInteger = new AtomicInteger(0);
        final CountDownLatch countDownLatch = new CountDownLatch(1000); // 相當於計數器，當所有都準備好了，再一起執行，模仿多並發，保證並發量
        final CountDownLatch countDownLatch2 = new CountDownLatch(1000); // 保證所有線程執行完了再打印atomicInteger的值
        ExecutorService executorService = Executors.newFixedThreadPool(10);
        
 
try {
            for (int i = 0; i < 1000; i++) {
                executorService.submit(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            countDownLatch.await(); //一直阻塞當前線程，直到計時器的值為0,保證同時並發
                        } catch
 
 (InterruptedException e) {
                            e.printStackTrace();
                        }
                        //每個線程增加1000次，每次加1
                        for (int j = 0; j < 1000; j++) {
                            atomicInteger.incrementAndGet();
                        }
                        countDownLatch2.countDown();
                    }
                });
                countDownLatch.countDown();
            }

            countDownLatch2.await();// 保證所有線程執行完
            System.out.println(atomicInteger);
            executorService.shutdown();
        }catch (Exception e){
            e.printStackTrace();
        }
    }

    public static void main(String[] args) throws InterruptedException {
        concurrenceTest();
    }
}

使用CountDownLatch模擬高並發場景