第 7 周作业：web 性能测压工具

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.net.HttpURLConnection;
import java.net.URL;
import java.io.InputStream;
import java.util.concurrent.CountDownLatch;
public class CapacityTestingTool {
    private final String url;
    private final int totalRequest;
    private final ExecutorService pool;
    public CapacityTestingTool(String url, int totalRequest, ExecutorService pool) {
        this.url = url;
        this.totalRequest = totalRequest;
        this.pool =  pool;
    }
    public double[] test() {
        CountDownLatch doneSignal = new CountDownLatch(totalRequest);
        Queue<Long> timeQueue = new ConcurrentLinkedQueue<>();
        for (int i = 0; i < totalRequest; i++) {
            pool.execute(new Runnable() {
                @Override
                public void run() {
                    HttpURLConnection con = null;
                    long startTime = System.nanoTime();
                    // Make HTTP request to the specified URL
                    try {
                        URL link = new URL(url);
                        con = (HttpURLConnection) link.openConnection();
                        con.setUseCaches(false);
                        con.setConnectTimeout(3000);
                        con.setRequestMethod("GET");
                        InputStream in = con.getInputStream();
                        BufferedReader reader = new BufferedReader(new InputStreamReader(in));
                        StringBuilder result = new StringBuilder();
                        String line;
                        while((line = reader.readLine()) != null) {
                            result.append(line);
                        }
                        //System.out.println(result.toString());
                        in.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    } finally {
                        if (con != null) {
                            con.disconnect();
                        }
                    }
                    long endTime = System.nanoTime();
                    timeQueue.add(endTime - startTime);
                    System.out.println(endTime - startTime);
                    doneSignal.countDown();
                }
            });
        }
        try {
            doneSignal.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        List<Long> times = new ArrayList<>(timeQueue);
        double avgResponseTime = getAvg(times) / 1000000000.0;
        double ninetyFivePercentileTime = get95Percentile(times) / 1000000000.0;
        return new double[]{avgResponseTime, ninetyFivePercentileTime};
    }
    private static double getAvg(List<Long> times) {
        long total = 0;
        for (long time : times) {
            total += time;
        }
        return total / (float)times.size();
    }
    private static long get95Percentile(List<Long> times) {
        Collections.sort(times);
        int index = (int) Math.ceil(95 / 100.0 * times.size());
        return times.get(index-1);
    }
    public static void main(String[] args) {
        ExecutorService pool = Executors.newFixedThreadPool(10);
        CapacityTestingTool tool = new CapacityTestingTool("https://www.baidu.com/", 100, pool);
        double[] metrics = tool.test();
        System.out.println("The average response time is " + metrics[0] + " seconds and the 95 " +
                "percentile response time is " + metrics[1] + " seconds");
        pool.shutdown();
    }
}

The average response time is 0.109775896 seconds and the 95 percentile response time is 0.520162642 seconds