Executors（线程池操作类）

一，常用方法

二，案例

package XianChengChildren;

import java.util.concurrent.*;

public class ThewadPoolTest1 {
    public static void main(String[] args) throws Exception {
//        ExecutorService pool = new ThreadPoolExecutor(3,5,8,
//                TimeUnit.SECONDS,
//                new LinkedBlockingQueue<>(4),
//                Executors.defaultThreadFactory(),
//                new ThreadPoolExecutor.AbortPolicy());
        //1,通过Executors创建一个线程池对象
        ExecutorService pool = Executors.newFixedThreadPool(3);
        //注意：核心线程数量应=CPU的核数+1（计算密集型任务）；CPU的核数*2（IO密集型任务）
        //例如；我的电脑为32核；计算密集型任务应填33，IO密集型任务应填64
        //Ctrl键+Alt键+Dcl键打开任务管理器查看性能逻辑处理器为CPU内核
       Future<String> f1 = pool.submit(new MyRunnable(100));
       Future<String> f2 = pool.submit(new MyRunnable(200));
       Future<String> f3 = pool.submit(new MyRunnable(300));
       Future<String> f4 = pool.submit(new MyRunnable(400));

        System.out.println(f1.get());
        System.out.println(f2.get());
        System.out.println(f3.get());
        System.out.println(f4.get());



    }
}

package XianChengChildren;

import java.util.concurrent.Callable;

public class MyRunnable implements Callable {
    private int n;

    public MyRunnable(int n) {
        this.n = n;
    }

    @Override
    public Object call() throws Exception {
        int sum=0;
        for (int i = 0; i <=n ; i++) {
            sum+=1;
        }
        return Thread.currentThread().getName()+"线程求出了1-"+n+"的和是"+sum;
    }
}

3，注意大型应用不能用Executors