Java 线程池 四种创建方式

public static void main(String[] args) {
		ExecutorService cachedThreadPool = Executors.newCachedThreadPool();
		for (int i = 0; i < 10; i++) {
			final int index = i;
			try {
				Thread.sleep(10);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
			cachedThreadPool.execute(new Runnable() {
				public void run() {
					System.out.println(index);
				}
			});
		}
	}

public static ExecutorService newCachedThreadPool() {
        return new ThreadPoolExecutor(0, Integer.MAX_VALUE,
                                      60L, TimeUnit.SECONDS,
                                      new SynchronousQueue<Runnable>());
    }

public static void main(String[] args) {
		ExecutorService fixedThreadPool = Executors.newFixedThreadPool(3);
		for (int i = 0; i < 10; i++) {
			final int index = i;
			fixedThreadPool.execute(new Runnable() {
				public void run() {
					try {
						System.out.println(index);
						Thread.sleep(10);
					} catch (InterruptedException e) {
						e.printStackTrace();
					}
				}
			});
		}
	}

public static ExecutorService newFixedThreadPool(int nThreads) {
        return new ThreadPoolExecutor(nThreads, nThreads,
                                      0L, TimeUnit.MILLISECONDS,
                                      new LinkedBlockingQueue<Runnable>());
    }

public static void main(String[] args) {
		ScheduledExecutorService scheduledThreadPool = Executors.newScheduledThreadPool(5);
		for (int i = 0; i < 10; i++) {
			scheduledThreadPool.schedule(new Runnable() {
				public void run() {
					System.out.println("delay 3 seconds");
				}
			}, 3, TimeUnit.SECONDS);
		}
	}

public static ScheduledExecutorService newScheduledThreadPool(int corePoolSize) {
        return new ScheduledThreadPoolExecutor(corePoolSize);
    }

public ScheduledThreadPoolExecutor(int corePoolSize) {
        super(corePoolSize, Integer.MAX_VALUE, 0, NANOSECONDS,
              new DelayedWorkQueue());
    }

public ThreadPoolExecutor(int corePoolSize,
                              int maximumPoolSize,
                              long keepAliveTime,
                              TimeUnit unit,
                              BlockingQueue<Runnable> workQueue) {
        this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,
             Executors.defaultThreadFactory(), defaultHandler);
    }

public static void main(String[] args) {
	ExecutorService singleThreadExecutor = Executors.newSingleThreadExecutor();
	for (int i = 0; i < 10; i++) {
		final int index = i;
		singleThreadExecutor.execute(new Runnable() {
			public void run() {
/*					System.out.println(index);*/
				try {
					System.out.println(index);
					Thread.sleep(2000);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
		});
	}
}

public static ExecutorService newSingleThreadExecutor() {
        return new FinalizableDelegatedExecutorService
            (new ThreadPoolExecutor(1, 1,
                                    0L, TimeUnit.MILLISECONDS,
                                    new LinkedBlockingQueue<Runnable>()));
    }

/**
 * ThreadPoolExecutor类的使用方法
 * 实现高并发: 在线程类中的run（）方法内设置Thread.sleep（long delta）； delta取值为: （并发开始时间戳 - 线程开始时间戳）
 * Created by Administrator on 2016/11/19.
 */
public class ThreadPoolExecutorTest {
    public static void main(String[] args) {

        //设置核心池大小
        int corePoolSize = 5;

        //设置线程池最大能接受多少线程

        //当前线程数大于corePoolSize、小于maximumPoolSize时, 超出corePoolSize的线程数的生命周期
        long keepActiveTime = 200;

        //设置时间单位, 秒
        TimeUnit timeUnit = TimeUnit.SECONDS;

        //设置线程池缓存队列的排队策略为FIFO, 并且指定缓存队列大小为5
        BlockingQueue<Runnable> workQueue = new ArrayBlockingQueue<Runnable>(5);

        //创建ThreadPoolExecutor线程池对象, 并初始化该对象的各种参数
        ThreadPoolExecutor executor = new ThreadPoolExecutor(corePoolSize, maximumPoolSize, keepActiveTime, timeUnit,workQueue);

        //往线程池中循环提交线程
        for (int i = 0; i < 15; i++) {
            //创建线程类对象
            MyTask myTask = new MyTask(i);
            //开启线程
            executor.execute(myTask);
            //获取线程池中线程的相应参数
            System.out.println("线程池中线程数目: " +executor.getPoolSize() + ", 队列中等待执行的任务数目: "+executor.getQueue().size() + ", 已执行完的任务数目: "+executor.getCompletedTaskCount());
        }
        //待线程池以及缓存队列中所有的线程任务完成后关闭线程池. 
        executor.shutdown();
    }
}
/**
 *线程类
 */
class MyTask implements Runnable {
    private int num;

    public MyTask(int num) {
        this.num = num;
    }

    @Override
    public void run() {
        System.out.println("正在执行task " + num );
        try {
            Thread.currentThread().sleep(5000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("task " + num + "执行完毕");
    }

    /**
     * 获取（未来时间戳-当前时间戳）的差值, 
     * 也即是: （每个线程的睡醒时间戳-每个线程的入睡时间戳）
     * 作用: 用于实现多线程高并发
     * @return
     * @throws ParseException
     */
    public long getDelta() throws ParseException {
        //获取当前时间戳
        long t1 = new Date().getTime();
        //获取未来某个时间戳（自定义, 可写入配置文件）
        String str = "2016-11-11 15:15:15";
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        long t2 = simpleDateFormat.parse(str).getTime();
        return t2 - t1;
    }
}