使用 ThreadPoolExecutor 建立多執行緒工具類

import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicInteger;

public class ThreadPoolUtils {

    private ThreadPoolExecutor pool = null;

    static Integer num = 0;


    /**
     * 獲取CPU核數
     */
    private static final int CORE_POOL_SIZE = Runtime.getRuntime().availableProcessors();
    private static final int MAXIMUM_POOL_SIZE = Runtime.getRuntime().availableProcessors() * 5;
    /**
     * 阻塞佇列大小
     */
    private  static  final int MAX_TASK_SIZE =  Integer.MAX_VALUE;

    /**
     * IO密集執行緒池配置
     * @return
     */
    public  ThreadPoolExecutor getIOInstance( ){
        return  getNewInstance(CORE_POOL_SIZE * 2 + 1 , MAXIMUM_POOL_SIZE,"IO",MAX_TASK_SIZE);
    }
    /**
     * CUP密集執行緒池配置
     * @return
     */
    public  ThreadPoolExecutor getCUPInstance( ){
        return  getNewInstance(CORE_POOL_SIZE, MAXIMUM_POOL_SIZE,"CUP",MAX_TASK_SIZE);
    }
    /**
     * 獲取物件
     * @param corePoolSize 核心執行緒數量
     * @param poolName 執行緒池名稱
     * @param maxThreadSize 最大執行緒數
     * @param maxTaskSize 最大阻塞任務數
     * @return
     */
    public ThreadPoolExecutor getNewInstance(int corePoolSize,int maxThreadSize,String poolName,int maxTaskSize){

        pool = createPool(corePoolSize,maxThreadSize,poolName,maxTaskSize);

        if(pool==null){
            throw new NullPointerException();
        }else{
            return pool;
        }
    }

    /**
     * 建立執行緒池
     * @param corePoolSize 核心執行緒數量
     * @param poolName 執行緒池名稱
     * @param maxThreadSize 最大執行緒數
     * @param maxTaskSize 最大阻塞任務數
     * @return
     */
    private ThreadPoolExecutor createPool(int corePoolSize,int maxThreadSize,String poolName,int maxTaskSize){

        return new ThreadPoolExecutor(corePoolSize,maxThreadSize,0,
                TimeUnit.SECONDS,new LinkedBlockingQueue<>(maxTaskSize),
                new CustomThreadFactory(poolName),
                new RejectedExecutionHandlerImpl());
    }

    /**
     * 執行緒工廠
     * 給執行緒命名
     */
    private class CustomThreadFactory implements ThreadFactory {

        private final String poolName;

        public CustomThreadFactory(String poolName){
            this.poolName = poolName;
        }

        private AtomicInteger count = new AtomicInteger(0);

        @Override
        public Thread newThread(Runnable r) {
            Thread t = new Thread(r);
            String nowThreadName = "";
            nowThreadName = poolName + count.addAndGet(1);
            t.setName(nowThreadName);
            return t;
        }
    }

    /**
     * 自定義拒絕策略
     */
    private class RejectedExecutionHandlerImpl implements RejectedExecutionHandler {

        @Override
        public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) {
            try{
                System.out.println("重回佇列");
                executor.getQueue().put(r);
            }catch (Exception e){

            }
        }
    }

    public static void main(String[] args){
        ThreadPoolExecutor executor = new ThreadPoolUtils().getNewInstance(3,8,"test",5);

        for (int i = 0;i<20;i++){
            System.out.println("提交第"+i+"個任務");
            executor.execute(()->{
                try {
                    System.out.println(Thread.currentThread().getName());
                    TimeUnit.SECONDS.sleep(10);
                    synchronized (num){
                        System.out.println("數字為："+num++);
                    }

                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            });
            System.out.println("提交第"+i+"個任務成功");
        }
        System.out.println("結束");
    }
}