Java 创建线程池的四种方式

痛定思痛。 2022-11-29 11:27 146阅读 0赞

1、newCachedThreadPool 创建一个可缓存线程池，如果线程池长度超过处理需要，可灵活回收空闲线程，若无可回收，则新建线程。

2、newFixedThreadPool 创建一个定长线程池，可控制线程最大并发数，超出的线程会在队列中等待。

3、newScheduledThreadPool 创建一个定长线程池，支持定时及周期性任务执行。

4、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(FIFO, LIFO, 优先级)执行。

**newCachedThreadPool**

创建一个可缓存线程池，如果线程池长度超过处理需要，可灵活回收空闲线程，

若无可回收，则新建线程。

package cn.dandelioncloud.thread;
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    public class Test111907 {
        public static void main(String[] args) {
            ExecutorService executorService = Executors.newCachedThreadPool();
            for(int i = 0; i < 10; i++) {
                final int temp = i;
                executorService.execute(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            Thread.sleep(1000);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                        System.out.println(Thread.currentThread().getName() + "  i=" + temp);
                    }
                });
            }
        }
    }
    public static ExecutorService newCachedThreadPool() {
        return new ThreadPoolExecutor(0, Integer.MAX_VALUE,60L, TimeUnit.SECONDS,new SynchronousQueue());
    }

**newFixedThreadPool**

创建一个定长线程池，可控制线程最大并发数，超出的线程会在队列中等待。

package cn.dandelioncloud.thread;
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    public class Test111907 {
        public static void main(String[] args) {
            ExecutorService executorService = Executors.newFixedThreadPool(3);
            for (int i = 0; i < 10; i++) {
                final int temp = i;
                executorService.execute(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            Thread.sleep(100);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                        System.out.println(Thread.currentThread().getName() + "  i=" + temp);
                    }
                });
            }
        }
    }
    public static ExecutorService newFixedThreadPool(int nThreads) {
        return new ThreadPoolExecutor(nThreads, nThreads,0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue());
    }

**newScheduledThreadPool**

创建一个定长线程池，支持定时及周期性任务执行。

package cn.dandelioncloud.thread;
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    import java.util.concurrent.ScheduledExecutorService;
    import java.util.concurrent.TimeUnit;
    public class Test111907 {
        public static void main(String[] args) {
            final long begin = System.currentTimeMillis();
            ExecutorService executorService = Executors.newScheduledThreadPool(3);
            for (int i = 0; i < 10; i++) {
                final int temp = i;
                final long time = begin;
                executorService.schedule(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            Thread.sleep(100);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                        System.out.println(Thread.currentThread().getName() + "  i=" + temp + "  time=" + (System.currentTimeMillis() - time));
                    }
                }, 5, TimeUnit.SECONDS);
            }
        }
    }
    public static ScheduledExecutorService newScheduledThreadPool(int corePoolSize) {
        return new ScheduledThreadPoolExecutor(corePoolSize);
    }
    public ScheduledThreadPoolExecutor(int corePoolSize) {
        super(corePoolSize, Integer.MAX_VALUE, 0, TimeUnit.NANOSECONDS, new DelayedWorkQueue());
    }

**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(FIFO, LIFO, 优先级)执行。