wait , notify 模拟 Queue

package com.itdoc.multi.sync009;

import java.util.LinkedList;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * @BLOG http://www.cnblogs.com/goodcheap
 * @DESCRIBE wait, notify 模拟 Queue
 * @AUTHOR WángChéngDá
 * @DATE 2017-03-25 9:26
 */
public class MyQueue {

    //1.创建容器
    private LinkedList<Object> list = new LinkedList<>();

    //2.构建计数器
    private AtomicInteger count = new AtomicInteger(0);

    //3.设置容器的容量上下限
    private final int minSize = 0;
    private final int maxSize;

    //4.创建设置容器上限的构造器
    public MyQueue(int maxSize) {
        this.maxSize = maxSize;
    }

    //5.设置对象锁
    final Object lock = new Object();

    //put: 将对象放入容器中, 假如容器容量到达上限, 将线程阻塞, 等待唤醒。
    public void put(Object obj) {
        synchronized (lock) {
            if (this.maxSize == count.get()) {
                try {
                    lock.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            //将对象放入容器
            list.add(obj);
            //计入计数器
            count.incrementAndGet();
            //假如一线程提取容器中元素而因为容器为空进入阻塞状态, 容器中添加元素后将其唤醒。
            lock.notify();
            System.out.println("Add a new element to " + obj);
        }
    }
    //take: 将对象从容器中取出, 假如容器没有任何元素, 将线程阻塞, 等待唤醒。
    public Object take() {
        Object obj = null;
        synchronized (lock) {
            if (this.minSize == count.get()) {
                try {
                    lock.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            //获取容器中第一个元素
            obj = list.removeFirst();
            //计入计数器
            count.decrementAndGet();
            //假如一线程向容器中放入元素而因容器到达上限进入阻塞状态, 将容器第一个元素取出后将其唤醒。
            lock.notify();
            System.out.println("Remove an element to " + obj);
        }
        return obj;
    }

    public static void main(String[] args) throws InterruptedException {
        final MyQueue mq = new MyQueue(5);
        mq.put("a");
        mq.put("b");
        mq.put("c");
        mq.put("d");
        mq.put("e");
        System.out.println("容器中元素有: " + mq.size() + "个。");

        new Thread(() -> {
            System.out.println("Enter the " + Thread.currentThread().getName());
            mq.put("f");
            mq.put("g");
            System.out.println(Thread.currentThread().getName() + " Thread stop...");
        }, "T1").start();

        TimeUnit.SECONDS.sleep(2);

        new Thread(() -> {
            System.out.println("Enter the " + Thread.currentThread().getName());
            mq.take();
            mq.take();
            System.out.println(Thread.currentThread().getName() + " Thread stop...");
        }, "T2").start();
        /**
         * 解决: ERROR: JDWP Unable to get JNI 1.2 environment, jvm->GetEnv() return code = -2
         * JDWP exit error AGENT_ERROR_NO_JNI_ENV(183):  [util.c:840]
         */
        System.exit(0);
    }

    private int size() {
        return this.count.get();
    }
}

控制台输出：

Add a new element to a
Add a new element to b
Add a new element to c
Add a new element to d
Add a new element to e
容器中元素有: 5个。
Enter the T1
Enter the T2
Remove an element to a
Remove an element to b
T2 Thread stop...
Add a new element to f
Add a new element to g