Java使用线程池和多线程实现并行计算(案例一)

Posted 2022-04-21 泡^泡

主要实现:

• 任务分割分步骤计算执行
• 执行结果有序的聚合在一起

package thread;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class ParallelComputeDemo 
    public static void main(String[] args) 
        long startTime = System.currentTimeMillis();
        List<Integer> results = getMultiple(1, 200);
        long endTime = System.currentTimeMillis();
        System.out.println("耗时1：" + (endTime -startTime));

        ExecutorService service = Executors.newFixedThreadPool(4);
        MyCallable t1 = new MyCallable(1, 30);
        MyCallable t2 = new MyCallable(31, 70);
        MyCallable t3 = new MyCallable(71, 140);
        MyCallable t4 = new MyCallable(141, 200);

    Future<List<Integer>> s1 = service.submit(t1);
    Future<List<Integer>> s2 = service.submit(t2);
    Future<List<Integer>> s3 = service.submit(t3);
    Future<List<Integer>> s4 = service.submit(t4);

    startTime = System.currentTimeMillis();
        try 
        System.out.println(s1.get());
        System.out.println(s2.get());
        System.out.println(s3.get());
        System.out.println(s4.get());
    catch (Exception e)
        e.printStackTrace();
    
    endTime = System.currentTimeMillis();
        System.out.println("耗时2：" + (endTime - startTime));
        service.shutdown();


    static class MyCallable implements Callable<List<Integer>>

        private int start;

        private int end;

        public int getStart() 
            return start;
        

        public void setStart(int start) 
            this.start = start;
        

        public int getEnd() 
            return end;
        

        public void setEnd(int end) 
            this.end = end;
        

        public MyCallable(int start, int end) 
            this.start = start;
            this.end = end;
        

        @Override
        public List<Integer> call() throws Exception 
            List<Integer> result = getMultiple(start, end);
            return result;
        
    

    public static List<Integer> getMultiple(int start, int end) 
        List<Integer> results = new ArrayList<>();
       for (int i = start; i <= end; i++)
           if(i % 6 == 0 && i != 0)
               results.add(i);
           
       
       return results;