/**
 * 自定义请求响应类
 */
public class HttpResponse {
    // 响应内容
    private String content;
    // 响应时间
    private long respTime;
    public String getContent() {
        return content;
    }
    public void setContent(String content) {
        this.content = content;
    }
    public long getRespTime() {
        return respTime;
    }
    public void setRespTime(long respTime) {
        this.respTime = respTime;
    }
    @Override
    public String toString() {
        return "HttpResponse{" +
                "content='" + content + '\'' +
                ", respTime='" + respTime +
                "ms'}";
    }
}

/**
 * 请求访问工具类
 */
public class HttpClient {
    /**
     * 获取连接信息
     *
     * @param url
     * @return
     */
    private static URLConnection getConnection(String url) {
        URLConnection connection = null;
        if (Optional.ofNullable(url).isPresent()) {
            try {
                connection = new URL(url).openConnection();
                connection.setRequestProperty("accept", "*/*");
                connection.setRequestProperty("connection", "Keep-Alive");
                connection.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return connection;
    }
    /**
     * GET方式请求简单实现
     *
     * @param url
     * @return
     */
    public static HttpResponse get(String url) {
        HttpResponse response = new HttpResponse();
        StringBuilder content = new StringBuilder();
        URLConnection connection = getConnection(url);
        try (BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()))) {
            long start = System.currentTimeMillis();
            connection.connect();
            String line = null;
            while ((line = in.readLine()) != null) {
                content.append(line);
            }
            response.setContent(content.toString());
            response.setRespTime(System.currentTimeMillis() - start);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return response;
    }
}

/**
 * 压力测试模拟器
 */
public class Simulator {
    private String url = null;
    private int sbc = 1;
    private int times = 1;
    /**
     * 测试模拟器构造方法
     *
     * @param url   测试地址
     * @param sbc   并发数
     * @param times 请求总次数
     */
    public Simulator(String url, int sbc, int times) {
        this.url = url;
        this.sbc = sbc;
        this.times = times;
    }
    /**
     * 启动压测
     * @return
     * @throws InterruptedException
     */
    public List<HttpResponse> start() throws InterruptedException {
        List<HttpResponse> respList = new ArrayList<>();
        ThreadPoolExecutor executor = new ThreadPoolExecutor(sbc, sbc,
                0L, TimeUnit.MILLISECONDS,
                new LinkedBlockingQueue<Runnable>());
        for (int i = 0; i < this.times; i++) {
            executor.execute(() -> {
                HttpResponse resp = HttpClient.get(this.url);
                respList.add(resp);
            });
        }
        while (executor.getActiveCount() > 0) {
            Thread.sleep(100);
        }
        executor.shutdown();
        return respList;
    }
    /**
     * 获取平均响应时间
     *
     * @param respList
     * @return
     */
    public long getAvgRespTime(List<HttpResponse> respList) {
        return Optional.ofNullable(respList).orElse(new ArrayList<>()).stream()
                .map(HttpResponse::getRespTime)
                .collect(Collectors.averagingLong(Long::longValue)).longValue();
    }
    /**
     * 获取${percent}%响应时间
     *
     * @param respList
     * @return
     */
    public long getAvgRespTime(List<HttpResponse> respList, int percent) {
        long avgRespTime = 0L;
        Optional<List<HttpResponse>> respTimesOptional = Optional.ofNullable(respList);
        if (respTimesOptional.isPresent()) {
            avgRespTime = respTimesOptional.get().stream()
                    .map(HttpResponse::getRespTime)
                    .sorted()
                    .collect(Collectors.toList())
                    .get(Math.max(Math.floorDiv(respList.size() * percent, 100) - 1, 0));
        }
        return avgRespTime;
    }
    /**
     * 打印压测结果
     *
     * @param respList
     */
    public void print(List<HttpResponse> respList) {
        System.out.println(String.format("并发 %d 访问 %s，总计访问 %d 次，压测结果：", this.sbc, this.url, this.times));
        System.out.println(String.format("平均响应时间: %d ms", this.getAvgRespTime(respList)));
        System.out.println(String.format("95%s响应时间: %d ms", "%", this.getAvgRespTime(respList, 95)));
    }
}

/**
 * 压力测试baidu
 */
public class SimulatorTest {
    @Test
    public void testSimulator() throws InterruptedException {
        String url = "http://www.baidu.com";
        int sbc = 10;
        int times = 100;
        Simulator testSimulator = new Simulator(url, sbc, times);
        List<HttpResponse> respList = testSimulator.start();
        testSimulator.print(respList);
    }
}