【JUC】ThreadPoolExecutor构造函数及拒绝策略

构造函数实现

public ThreadPoolExecutor(int corePoolSize,
                              int maximumPoolSize,
                              long keepAliveTime,
                              TimeUnit unit,
                              BlockingQueue<Runnable> workQueue,
                              ThreadFactory threadFactory,
                              RejectedExecutionHandler handler) {
    if (corePoolSize < 0 ||
        maximumPoolSize <= 0 ||
        maximumPoolSize < corePoolSize ||
        keepAliveTime < 0)
        throw new IllegalArgumentException();
    if (workQueue == null || threadFactory == null || handler == null)
        throw new NullPointerException();
    this.corePoolSize = corePoolSize;
    this.maximumPoolSize = maximumPoolSize;
    this.workQueue = workQueue;
    this.keepAliveTime = unit.toNanos(keepAliveTime);
    this.threadFactory = threadFactory;
    this.handler = handler;
}
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构造函数说明

ThreadPoolExecutor构造函数的参数最多有7个参数，参数分别为：

拒绝策略

拒绝策略是ThreadPoolExecutor无法执行任务且任务也无法排队时的处理策略，这种情况下ThreadPoolExecutor中的线程数量为maximumPoolSize且workQueue已满。
ThreadPoolExecutor内置四种任务拒绝策略：