public?void?execute(Runnable?command)?{
????if?(command?==?null)
????????throw?new?NullPointerException();
????int?c?=?ctl.get();
????//?當(dāng)前工作的線程數(shù)小于核心線程數(shù)
????if?(workerCountOf(c)?<?corePoolSize)?{
????????//?創(chuàng)建新的線程執(zhí)行此任務(wù)
????????if?(addWorker(command,?true))
????????????return;
????????c?=?ctl.get();
????}
????//?檢查線程池是否處于運(yùn)行狀態(tài)，如果是則把任務(wù)添加到隊(duì)列
????if?(isRunning(c)?&&?workQueue.offer(command))?{
????????int?recheck?=?ctl.get();
????????//?再次檢線程池是否處于運(yùn)行狀態(tài)，防止在第一次校驗(yàn)通過后線程池關(guān)閉
????????//?如果是非運(yùn)行狀態(tài)，則將剛加入隊(duì)列的任務(wù)移除
????????if?(!?isRunning(recheck)?&&?remove(command))
????????????reject(command);
????????//?如果線程池的線程數(shù)為?0?時(shí)（當(dāng)?corePoolSize?設(shè)置為?0?時(shí)會(huì)發(fā)生）
????????else?if?(workerCountOf(recheck)?==?0)
????????????addWorker(null,?false);?//?新建線程執(zhí)行任務(wù)
????}
????//?核心線程都在忙且隊(duì)列都已爆滿，嘗試新啟動(dòng)一個(gè)線程執(zhí)行失敗
????else?if?(!addWorker(command,?false))?
????????//?執(zhí)行拒絕策略
????????reject(command);
}

public static void main(String[] args) {
    // 任務(wù)的具體方法
    Runnable runnable = new Runnable() {
        @Override
        public void run() {
            System.out.println("當(dāng)前任務(wù)被執(zhí)行,執(zhí)行時(shí)間:" + new Date() +
                               " 執(zhí)行線程:" + Thread.currentThread().getName());
            try {
                // 等待 1s
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    };
    // 創(chuàng)建線程,線程的任務(wù)隊(duì)列的長度為 1
    ThreadPoolExecutor threadPool = new ThreadPoolExecutor(1, 1,
                                                           100, TimeUnit.SECONDS, new LinkedBlockingQueue<>(1),
                                                           new ThreadPoolExecutor.DiscardPolicy());
    // 添加并執(zhí)行 4 個(gè)任務(wù)
    threadPool.execute(runnable);
    threadPool.execute(runnable);
    threadPool.execute(runnable);
    threadPool.execute(runnable);
    // 線程池執(zhí)行完任務(wù)，關(guān)閉線程池
    threadPool.shutdown();
}

public static void main(String[] args) {
    // 任務(wù)的具體方法
    Runnable runnable = new Runnable() {
        @Override
        public void run() {
            System.out.println("當(dāng)前任務(wù)被執(zhí)行,執(zhí)行時(shí)間:" + new Date() +
                               " 執(zhí)行線程:" + Thread.currentThread().getName());
            try {
                // 等待 1s
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    };
    // 創(chuàng)建線程,線程的任務(wù)隊(duì)列的長度為 1
    ThreadPoolExecutor threadPool = new ThreadPoolExecutor(1, 1,
                                                           100, TimeUnit.SECONDS, new LinkedBlockingQueue<>(1),
                                                           new ThreadPoolExecutor.AbortPolicy()); // 顯式指定拒絕策略，也可以忽略此設(shè)置，它為默認(rèn)拒絕策略
    // 添加并執(zhí)行 4 個(gè)任務(wù)
    threadPool.execute(runnable);
    threadPool.execute(runnable);
    threadPool.execute(runnable);
    threadPool.execute(runnable);
    // 線程池執(zhí)行完任務(wù)，關(guān)閉線程池
    threadPool.shutdown();
}

public static void main(String[] args) {
    // 任務(wù)的具體方法
    Runnable runnable = new Runnable() {
        @Override
        public void run() {
            System.out.println("當(dāng)前任務(wù)被執(zhí)行,執(zhí)行時(shí)間:" + new Date() +
                               " 執(zhí)行線程:" + Thread.currentThread().getName());
            try {
                // 等待 1s
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    };
    // 創(chuàng)建線程,線程的任務(wù)隊(duì)列的長度為 1
    ThreadPoolExecutor threadPool = new ThreadPoolExecutor(1, 1,
                                                           100, TimeUnit.SECONDS, new LinkedBlockingQueue<>(1),
                                                           new RejectedExecutionHandler() {
                                                               @Override
                                                               public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) {
                                                                   // 執(zhí)行自定義拒絕策略的相關(guān)操作
                                                                   System.out.println("我是自定義拒絕策略~");
                                                               }
                                                           });
    // 添加并執(zhí)行 4 個(gè)任務(wù)
    threadPool.execute(runnable);
    threadPool.execute(runnable);
    threadPool.execute(runnable);
    threadPool.execute(runnable);
}