public class PerformanceTest {
    /**
     * 测试某个url的平均响应时间，95%响应时间
     *
     * @param url             测试url
     * @param totalRequestNum 总请求数
     * @param concurrentNum   并发数
     * @throws InterruptedException
     */
    public void test(String url, int totalRequestNum, int concurrentNum) throws InterruptedException {
        ExecutorService executorService = Executors.newFixedThreadPool(concurrentNum);
        AtomicLong atomicLong = new AtomicLong();
        CopyOnWriteArrayList<Long> copyOnWriteArrayList = new CopyOnWriteArrayList<>();
        CountDownLatch countDownLatch = new CountDownLatch(totalRequestNum);
        for (int i = 0; i < totalRequestNum; i++) {
            executorService.submit(() -> {
                try {
                    URL url1 = new URL(url);
                    HttpURLConnection urlConnection = (HttpURLConnection) url1.openConnection();
                    long st = System.currentTimeMillis();
                    urlConnection.connect();
                    long costTime = System.currentTimeMillis() - st;
                    atomicLong.addAndGet(costTime);
                    copyOnWriteArrayList.add(costTime);
                    countDownLatch.countDown();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            });
        }
        countDownLatch.await();
        System.out.println("平均响应时间:" + atomicLong.get() / totalRequestNum + "ms");
        copyOnWriteArrayList.sort(Long::compareTo);
        System.out.println("95%响应时间:" + copyOnWriteArrayList.get(Math.round(0.95f * copyOnWriteArrayList.size())) + "ms");
        executorService.shutdown();
    }
    public static void main(String[] args) throws IOException, InterruptedException {
        new PerformanceTest().test("http://www.baidu.com", 100, 10);
    }
}