java线程池使用Demo（ThreadPoolExecutor方式）

川长思鸟来 2023-06-15 09:48 22阅读 0赞

package com.zhh.threadpool;
    
    import java.util.concurrent.*;
    
    /**
     * @Author: zhanghh
     * @Date: 2019/11/11 15:20
     * @Description: 线程池使用demo
     */
    public class TestThreadPool {
        public static void main(String[] args) throws ExecutionException, InterruptedException {
            ExecutorService executorService = getExecutorService();
            Future<String> f1 = submitTask(executorService, new Callable<String>() {
                @Override
                public String call() throws Exception {
                    System.out.println("Thread 1 is running……");
                    Thread.sleep(5000); //睡5秒
                    return "1 done!";
                }
            });
            Future<String> f2 = submitTask(executorService, new Callable<String>() {
                @Override
                public String call() throws Exception {
                    System.out.println("Thread 2 is running……");
                    Thread.sleep(5000); //睡5秒
                    return "2 done!";
                }
            });
    
            Future<String> f3 = submitTask(executorService, new Callable<String>() {
                @Override
                public String call() throws Exception {
                    System.out.println("Thread 3 is running……");
                    Thread.sleep(5000); //睡5秒
                    return "3 done!";
                }
            });
    
            Future<String> f4 = submitTask(executorService, new Callable<String>() {
                @Override
                public String call() throws Exception {
                    System.out.println("Thread 4 is running……");
                    Thread.sleep(5000); //睡5秒
                    return "4 done!";
                }
            });
    
            Future<String> f5 = submitTask(executorService, new Callable<String>() {
                @Override
                public String call() throws Exception {
                    System.out.println("Thread 5 is running……");
                    Thread.sleep(5000); //睡5秒
                    return "5 done!";
                }
            });
            Future<String> f6 = submitTask(executorService, new Callable<String>() {
                @Override
                public String call() throws Exception {
                    System.out.println("Thread 6 is running……");
                    Thread.sleep(5000); //睡5秒
                    return "6 done!";
                }
            });
    
            System.out.println(f1.get());
            System.out.println(f2.get());
            System.out.println(f3.get());
            System.out.println(f3.get());
            System.out.println(f5.get());
    
    
        }
    
        /**
         * 提交一个任务到线程池
         * 必须要自行处理提交异常，否则线程执行会中断，即使提交成功也无法继续执行
         * @param executorService
         * @param callable
         * @return
         */
        public static Future<String> submitTask(ExecutorService executorService, Callable<String> callable){
            try{
                Future<String> f = executorService.submit(callable);
                return f;
            }catch (Exception e){
                e.printStackTrace();
            }
            return null;
        }
    
        /**
         * 获取线程池
         * @return
         */
        public static ExecutorService getExecutorService(){
            //线程池的size = cpu核心数
            int poolSize = Runtime.getRuntime().availableProcessors();
            //超出队列的size，再继续添加任务，会直接根据RejectedExecutionHandler来决定处理新任务的策略
            //等待队列大小
            BlockingQueue<Runnable> queue = new ArrayBlockingQueue<>(100);
            //AbortPolicy : 对于超出队列大小后面再添加的任务直接抛异常
            //DiscardPolicy	: 什么也不做，直接忽略
            //CallerRunsPolicy : 使用此策略，如果添加到线程池失败，那么主线程会自己去执行该任务，不会等待线程池中的线程去执行。就像是个急脾气的人，我等不到别人来做这件事就干脆自己干。
            RejectedExecutionHandler handler = new ThreadPoolExecutor.CallerRunsPolicy();
            ExecutorService executorService = new ThreadPoolExecutor(poolSize, poolSize,
                    0, TimeUnit.SECONDS, queue, handler);
            return executorService;
        }
    
    }