Java-五种线程池，四种拒绝策略，三种阻塞队列-转

Java-五种线程池，四种拒绝策略，三种阻塞队列

三种阻塞队列：
    BlockingQueue workQueue = null;
    workQueue = new ArrayBlockingQueue<>(5);//基于数组的先进先出队列，有界
    workQueue = new LinkedBlockingQueue<>();//基于链表的先进先出队列，无界
    workQueue = new SynchronousQueue<>();//无缓冲的等待队列，无界
四种拒绝策略：
    RejectedExecutionHandler rejected = null;
    rejected = new ThreadPoolExecutor.AbortPolicy();//默认，队列满了丢任务抛出异常
    rejected = new ThreadPoolExecutor.DiscardPolicy();//队列满了丢任务不异常
    rejected = new ThreadPoolExecutor.DiscardOldestPolicy();//将最早进入队列的任务删，之后再尝试加入队列
    rejected = new ThreadPoolExecutor.CallerRunsPolicy();//如果添加到线程池失败，那么主线程会自己去执行该任务
五种线程池：
    ExecutorService threadPool = null;
    threadPool = Executors.newCachedThreadPool();//有缓冲的线程池，线程数 JVM 控制
    threadPool = Executors.newFixedThreadPool(3);//固定大小的线程池
    threadPool = Executors.newScheduledThreadPool(2);
    threadPool = Executors.newSingleThreadExecutor();//单线程的线程池，只有一个线程在工作
    threadPool = new ThreadPoolExecutor();//默认线程池，可控制参数比较多  

以下是创建无界队列，此处因为是无界队列，所以线程到了核心线程数不会再增加，队列默认Integer.MAX，基本不会遇到拒绝策略 

int corePoolSize = Runtime.getRuntime().availableProcessors();        
ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(corePoolSize, corePoolSize , 5L,
            TimeUnit.SECONDS, new LinkedBlockingQueue<>(), new ThreadPoolExecutor.CallerRunsPolicy());