CompletableFuture、parallelStream学习测试对比

参考链接：https://www.cnblogs.com/taiyonghai/p/9397394.html

import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Date;
import java.util.List;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.stream.Collectors;

public class Main {

  public static void main(String[] args) {

    System.out.println("Hello World!");
    testAllOfAnyOf();
    testParallelStream();
    testOneFunAsync();
    testOneFunAsyncWithThreadPool();
  }

  public static void printlnConsole(String msg){
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    String time=sdf.format(new Date());
    System.out.println(String.format("[%s]%s", time, msg));
  }

  /**
   * 多任务单次异步执行
   */
  public static void testMyFun(){
    long start=System.currentTimeMillis();
    try{
      int id=1;
      printlnConsole("调度异步任务。。。。。");
      CompletableFuture futureClassCount=CompletableFuture.supplyAsync(()->getClassCount(id));
      CompletableFuture futureStudentCount=CompletableFuture.supplyAsync(()->getStudentCount(id));

      printlnConsole("获取异步过程。。。。");
      Object classCount=futureClassCount.get();
      Object studentCount=futureStudentCount.get();
      printlnConsole("异步任务结果获取完成");
      printlnConsole("classCount:"+classCount);
      printlnConsole("studentCount:"+studentCount);
    }catch (Exception e){
      e.printStackTrace();
    }
    long end=System.currentTimeMillis();
    printlnConsole("系统运行时间为："+(end-start)/1000);
  }

  /**
   * 并行指定等待全部结果或等待任意结果
   */
  public static void testAllOfAnyOf(){
    long start=System.currentTimeMillis();
    try{
      List ids = Arrays.asList(1, 2,3,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,8,9,0,3, 5);//准备的请求参数
      printlnConsole("调度异步任务。。。。。testAllOfAnyOf*******************************8");
      //创建异步方法数组
      CompletableFuture[] futures = ids.stream().map(id -> CompletableFuture.supplyAsync(() -> getClassName(id))).toArray(size -> new CompletableFuture[size]);
      //指定该异步方法数组的子任务线程等待类型
      //CompletableFuture.anyOf(futures).join();//anyOf()为任意一个子任务线程执行完毕后返回
      CompletableFuture.allOf(futures).join();//allOf()为等待所有子任务线程全部执行完毕后返回


      printlnConsole("获取异步任务结果：");
      for (CompletableFuture f : futures) {
        //Object obj = f.getNow(1);//getNow()表示我需要立即拿到结果，如果当前的线程并未执行完成，则使用我传入的值进行任务调用，参数为无法获取结果时使用我传入的值
        Object obj = f.get();//get()获取子线程运算的结果，会抛出检查到的异常
        //Object obj = f.join();//join()获取子线程运算的结果，不会抛出异常
        printlnConsole(String.valueOf(obj));
      }
    }catch (Exception e){
      e.printStackTrace();
    }
    long end=System.currentTimeMillis();
    printlnConsole("系统运行时间为："+(end-start)/1000);
  }

  public static String getClassName(int id) {
    try {
      Thread.sleep(id * 1000);
      printlnConsole("getClassName(" + id + ")执行完毕");
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
    return "taiyonghai-" + id;
  }

  public static void testParallelStream(){
    long start=System.currentTimeMillis();
    try{
      printlnConsole("调用异步任务...****************testParallelStream*************");
      List ids = Arrays.asList(1, 2,3,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,8,9,0,3, 5);//准备的请求参数
      //串行执行会等待每一个方法执行完毕后在继续执行下一个
      //List names = ids.stream().map(id -> getStudentName(id)).collect(Collectors.toList());
      //并行执行会同时调用多个方法待全部执行完毕后一起返回（parallelStream是非线程安全的，配合collect达到线程安全，后续验证一下）
      List names = ids.parallelStream().map(id -> getClassName(id)).collect(Collectors.toList());

      printlnConsole("获取异步任务结果：");
      names.forEach(item -> printlnConsole(item));

    }catch (Exception e){
      e.printStackTrace();
    }
    long end=System.currentTimeMillis();
    printlnConsole("系统运行时间为："+(end-start)/1000);
  }

  /**
   * 单任务多次异步执行
   */
  public static void testOneFunAsync(){
    long start=System.currentTimeMillis();
    try{
      printlnConsole("调用异步任务...****************testOneFunAsync*************");
      List ids = Arrays.asList(1, 2,3,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,8,9,0,3, 5);//准备的请求参数
      List> futures = ids.stream().map(id -> CompletableFuture.supplyAsync(() -> getClassName(id))).collect(Collectors.toList());

      //不用并行流parallelStream()调用时就不会阻断线程执行

      printlnConsole("获取异步任务结果：");
      futures.forEach(f -> {
        try {
          Object obj = f.get();
          printlnConsole(String.valueOf(obj));
        } catch (InterruptedException e) {
          e.printStackTrace();
        } catch (ExecutionException e) {
          e.printStackTrace();
        }
      });

    }catch (Exception e){
      e.printStackTrace();
    }
    long end=System.currentTimeMillis();
    printlnConsole("系统运行时间为："+(end-start)/1000);
  }

  /**
   * 手动配置线程执行器的线程池大小
   */
  private final static Executor myExecutor = Executors.newFixedThreadPool(20, new ThreadFactory() {
    @Override
    public Thread newThread(Runnable r) {
      Thread t = new Thread(r);
      //使用守护线程保证不会阻止程序的关停
      t.setDaemon(true);
      return t;
    }
  });

  /**
   *
   */
  public static void testOneFunAsyncWithThreadPool(){
    long start=System.currentTimeMillis();
    try{
      printlnConsole("调用异步任务...****************testOneFunAsyncWithThreadPool带有线程池的*************");
      List ids = Arrays.asList(1, 2,3,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,8,9,0,3, 5);//准备的请求参数
      List> futures = ids.stream().map(id -> CompletableFuture.supplyAsync(() -> getClassName(id), myExecutor)).collect(Collectors.toList());

      //不用并行流parallelStream()调用时就不会阻断线程执行

      printlnConsole("获取异步任务结果：");
      futures.forEach(f -> {
        try {
          Object obj = f.get();
          printlnConsole(String.valueOf(obj));
        } catch (InterruptedException e) {
          e.printStackTrace();
        } catch (ExecutionException e) {
          e.printStackTrace();
        }
      });

    }catch (Exception e){
      e.printStackTrace();
    }
    long end=System.currentTimeMillis();
    printlnConsole("系统运行时间为："+(end-start)/1000);
  }
  public static int getClassCount(int id) {

    try {
      Thread.sleep(2000);
      printlnConsole("getClassCount(" + id + ")执行完毕");
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
    return 20;
  }

  public static int getStudentCount(int id) {
    try {
      Thread.sleep(1000);
      printlnConsole("getStudentCount(" + id + ")执行完毕");
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
    return 100;
  }
}

结果：

调度异步任务。。。。。testAllOfAnyOf*******************************

系统运行时间为：38

调用异步任务...****************testParallelStream*************

系统运行时间为：29

调用异步任务...****************testOneFunAsync*************

系统运行时间为：38

调用异步任务...****************testOneFunAsyncWithThreadPool带有线程池的*************

系统运行时间为：9