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