自定义简单线程池

                                 第一节

package threadpool;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.stream.IntStream;

/*
 * 
 */
public class SimpleThreadPool {
	private final int size;
	private final static int DEFAULT_SIZE = 10;
	private static volatile int seq = 0;
	private final static String THREAD_PREFIX = "SIMPLE_THREAD_POOL_";
	private final static ThreadGroup GROUP = new ThreadGroup("POOL_GROUP");
	private final static LinkedList<Runnable> TASK_QUEUE = new LinkedList<>();
	private final static List<WorkerTask> THREAD_QUEUE = new ArrayList<>();

	private static enum TaskState {
		FREE, RUNNING, BLOCKED, DEAD
	}

	public SimpleThreadPool() {
		this(DEFAULT_SIZE);
	}

	public SimpleThreadPool(int size) {
		this.size = size;
		init();
	}

	/*
	 * 初始化10个工作队列
	 */
	private void init() {
		for (int i = 0; i < size; i++) {
			createWorkTask();
		}
	}

	/**
	 * 提交任务
	 * 
	 * @param runnable
	 */
	public void submit(Runnable runnable) {
		synchronized (TASK_QUEUE) {
			TASK_QUEUE.addLast(runnable);
			TASK_QUEUE.notifyAll();

		}

	}

	/**
	 * 工作任务 每个任务需要开启一个线程
	 */
	private void createWorkTask() {
		WorkerTask task = new WorkerTask(GROUP, THREAD_PREFIX + (seq++));
		task.start();
		TASK_QUEUE.add(task);
	}


	public static void main(String[] args) {
		SimpleThreadPool threadPool = new SimpleThreadPool();
		IntStream.range(0, 10).forEach(i -> threadPool.submit(
				() -> {
					System.out.println("The runable: " + i + " be serviced by: " + Thread.currentThread() + " start");
						try {
							Thread.sleep(10000);
						} catch (InterruptedException e) {
							e.printStackTrace();
						}
					System.out
							.println(
									"The runable: " + i + " be serviced by: " + Thread.currentThread() + " finished");
				})
		
			);
	}

	private static class WorkerTask extends Thread {
		private volatile TaskState taskState = TaskState.FREE;

		public TaskState getTaskState() {
			return this.taskState;

		}
		public WorkerTask(ThreadGroup group, String name) {
			super(group, name);
		}

		@Override
		public void run() {
			OUTER:
			if (this.taskState != TaskState.DEAD) {
				Runnable runnable;
				synchronized (TASK_QUEUE) {
					while (TASK_QUEUE.isEmpty()) {
						try {
							taskState=TaskState.BLOCKED;
							TASK_QUEUE.wait();
						} catch (InterruptedException e) {
							e.printStackTrace();
							break OUTER;
						}

					}
					runnable = TASK_QUEUE.removeFirst();

				}
				if (runnable != null) {
					taskState = TaskState.RUNNING;
					runnable.run();
					taskState = TaskState.FREE;
				}
			}
		}

	}
}