使用多线程优化for循环请求http接口

package com.test.list;

import com.alibaba.fastjson.JSON;
import com.google.common.util.concurrent.ThreadFactoryBuilder;

import java.util.*;
import java.util.concurrent.*;

public class OneWanListRepeat {

    private static ExecutorService executor = new ThreadPoolExecutor(20, 20, 0L, TimeUnit.MILLISECONDS,
            new LinkedBlockingQueue<>(1024), new ThreadFactoryBuilder().build(), new ThreadPoolExecutor.AbortPolicy());

    private static int page = 1;
    private static int size = 100;
    private static int total = 100000;

    public static void main(String[] args) {
        // 添加参数
        long startTime1 = System.currentTimeMillis();
        List<ElementTest> list = new ArrayList<>();
        for (int i = 0; i < total; i++) {
            ElementTest test = new ElementTest();
            test.setName("name_" + i);
            test.setId("id_" + i);
            list.add(test);

            if (i == 999) {
                ElementTest test999 = new ElementTest();
                test999.setName("name_" + i);
                test999.setId("id_" + i);
                list.add(test999);
            }

            if (i == 8888) {
                ElementTest test8888 = new ElementTest();
                test8888.setName("name_" + i);
                test8888.setId("id_" + i);
                list.add(test8888);
            }
        }
        long endTime1 = System.currentTimeMillis();
        System.out.println("time1=" + (endTime1 - startTime1));

        // 使用多线程模拟分页查询http接口，并获取返回值
        long startTime3 = System.currentTimeMillis();
        int maxPage = total % size == 0 ? total / size : total / size + 1;
        CountDownLatch downLatch = new CountDownLatch(maxPage);
        ConcurrentHashMap<Integer, String> map = new ConcurrentHashMap();
        try {
            for (int i = 1; i <= maxPage; i++) {
                Integer integer = new Integer(i);
                System.out.println("This is ==" + i + "==");
                Callable thread = () -> {
                    String uuid = httpRequest();
                    downLatch.countDown();
                    return uuid;
                };
                Future<String> futureUUid = (Future<String>) executor.submit(thread);
                map.put(integer, futureUUid.get());
            }
            downLatch.await();
        } catch (InterruptedException | ExecutionException e) {
            e.printStackTrace();
        } finally {
            downLatch.countDown();
            executor.shutdown();
        }
        long endTime3 = System.currentTimeMillis();
        System.out.println("This is main 主线程");
        System.out.println("mapSize=" + map.size());
        System.out.println("map==========" + map);
        System.out.println("time3=" + (endTime3 - startTime3));

        long startTime2 = System.currentTimeMillis();
        List<ElementTest> elementTests = getRepeat(list);
        long endTime2 = System.currentTimeMillis();
        System.out.println("time2=" + (endTime2 - startTime2));
        System.out.println("result=" + JSON.toJSON(elementTests));
    }

    // 模拟获取重复元素
    private static List<ElementTest> getRepeat(List<ElementTest> list) {
        List<ElementTest> result = new ArrayList<>();
        Map<String, Integer> map = new HashMap<>();
        int size = list.size();
        for (int i = 0; i < size; i++) {
            ElementTest test = list.get(i);
            if (map.get(test.getId()) == null) {
                map.put(test.getId(), 1);
            } else if (map.get(test.getId()) == 1) {
                result.add(test);
                map.put(test.getId(), 2);
            } else {
                map.put(test.getId(), 2);
            }
        }
        return result;
    }

    public static String httpRequest() {
        //模拟http耗时
        try {
            TimeUnit.SECONDS.toMillis(1000);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return UUID.randomUUID().toString().substring(0, 3);
    }
}


class ElementTest {
    private String name;
    private String id;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }
}

原文地址：http://www.cnblogs.com/likeloves/p/16818038.html