使用工具类Exectors创建线程池

大型并发项目不能使用Executors 通过ThreadPoolExector的方式

核心线程配置方式:

计算密集型的任务核心线程数量 =CPU的核数 + 1
IO密集型的任务核心线程数量 =CPU的核数*2

演示:

Callable

import java.util.concurrent.Callable;public class MyCallable implements Callable<String> {private int n;public MyCallable(int n){this.n = n;}@Overridepublic  String call() throws Exception{int sum = 0;for (int i = 0; i <= n; i++) {sum +=i;}return Thread.currentThread().getName() + "输出"+sum;}
}

使用:

import java.util.concurrent.*;public class ThreadpoolTest3 {public static void main(String[] args) throws Exception {/** public ThreadPoolExecutor(int corePoolSize,int maximumPoolSize,long keepAliveTime,TimeUnit unit,BlockingQueue<Runnable> workQueue)*///创建线程池对象/** ExecutorService pool =  new ThreadPoolExecutor(3,5,8,TimeUnit.SECONDS,new LinkedBlockingQueue<>(4),Executors.defaultThreadFactory(),new ThreadPoolExecutor.AbortPolicy());//线程池满了的拒绝策略*///使用工具类创建线程池//大型并发项目 不能使用Executors  通过ThreadPoolExector的方式ExecutorService pool = Executors.newFixedThreadPool(3);//计算密集型的任务  核心线程数量 =CPU的核数 + 1//IO密集型的任务 核心线程数量 =CPU的核数*2//线程池处理Runnable任务Future<String> f1 = pool.submit(new MyCallable(100));Future<String> f2 = pool.submit(new MyCallable(200));Future<String> f3 = pool.submit(new MyCallable(300));Future<String> f4 = pool.submit(new MyCallable(400));System.out.println(f1.get());System.out.println(f2.get());System.out.println(f3.get());System.out.println(f4.get());pool.shutdown();      //当所有线程都被处理完  关闭//pool.shutdownNow(); //立即关闭 返回未处理的线程}
}

效果: