Executors提供四种线程池

Java通过Executors提供四种线程池，分别为：

• newCachedThreadPool创建一个可缓存线程池，如果线程池长度超过处理需求，可以灵活回收空闲线程，若无可回收则新建线程
• newFixedThreadPool创建一个定长线程池，可以控制线程最大并发数，超过的线程会在队列中等待
• newScheduledThreadPool创建一个定长线程池，支持定时及周期性任务执行
• newSingleThreadExecutor创建一个单线程化的线程池，它只会用唯一的工作线程来执行任务，保证所有任务按照指定顺序执行

newCachedThreadPool

ExecutorService cachedThreadPool = Executors.newCachedThreadPool();
cachedThreadPool.execute(new Runnable() {
    @Override
    public void run() {
        //do something
    }
});

newFixedThreadPool

ExecutorService fixedThreadPool = Executors.newFixedThreadPool(3);
fixedThreadPool.execute(new Runnable() {
    @Override
    public void run() {
        //do something
    }
});

newScheduledThreadPool

//延迟三秒执行
ScheduledExecutorService scheduledThreadPool = Executors.newScheduledThreadPool(5);
scheduledThreadPool.schedule(new Runnable() {
    @Override
    public void run() {
        //do something
    }
}, 3, TimeUnit.SECONDS);

//表示延迟1秒后每隔3秒钟执行一次
scheduledThreadPool.scheduleAtFixedRate(new Runnable() {
    @Override
    public void run() {
        //do something
    }
}, 1, 3, TimeUnit.SECONDS);

newSingleThreadExecutor

ExecutorService singleThreadExecutor = Executors.newSingleThreadExecutor();
singleThreadExecutor.execute(new Runnable() {
    @Override
    public void run() {
        //do something
    }
});