java-线程池工具类

package thread.pool;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

public class ThreadPoolUtil {

    static ExecutorService cachedThreadPool;

    static ExecutorService fixedThreadPool;

    static ScheduledExecutorService scheduledThreadPool;

    static ExecutorService singleThreadPool;

    static ExecutorService cachedThreadPoolRun(Runnable runnable) {
        if (cachedThreadPool == null)
            cachedThreadPool = Executors.newCachedThreadPool();
        cachedThreadPool.submit(runnable);
        return cachedThreadPool;
    }

    public static ExecutorService fixedThreadPoolRun(Runnable runnable) {
        if (fixedThreadPool == null)
            fixedThreadPool = Executors.newFixedThreadPool(Runtime.getRuntime()
                    .availableProcessors());
        fixedThreadPool.submit(runnable);
        return fixedThreadPool;
    }

    public static ExecutorService scheduledThreadPoolRun(Runnable runnable, long delay, TimeUnit unit) {
        if (scheduledThreadPool == null)
            scheduledThreadPool = Executors.newScheduledThreadPool(Runtime.getRuntime()
                    .availableProcessors());
        scheduledThreadPool.schedule(runnable, delay, unit);
        return scheduledThreadPool;
    }

    public static ExecutorService singleThreadPoolRun(Runnable runnable) {
        if (singleThreadPool == null)
            singleThreadPool = Executors.newSingleThreadExecutor();
        singleThreadPool.submit(runnable);
        return singleThreadPool;
    }

    public static void main(String[] args) {
        final Long startTime = System.currentTimeMillis();
        ExecutorService executorService = null;

        for (int i = 0; i < 1000000; i++) {
//            System.out.println(finalI);
            final int finalI = i;
            Runnable task = () -> System.out.println(finalI);
            executorService = ThreadPoolUtil.fixedThreadPoolRun(task);
        }

        if (executorService != null) {
            executorService.shutdown();
        }

        while (true) {
            if (executorService.isTerminated()) {
                System.out.println("所有的子线程都结束了！");
                break;
            }
        }

        final Long stopTime = System.currentTimeMillis();
        System.out.println("---------------------------");
        System.out.println(stopTime - startTime);

    }

}