一：基本特性

二：实现原理

三：实现代码

一：基本特性

    先进先出、写入队列空间不足时会阻塞、获取队列数据是队列为空会阻塞

二：实现原理

    初始化队列、写入队列、消费队列

初始化队列

private String[] items = new String[5];private Object full = new Object();private Object empty = new Object();private static int count;private static int putIndex = 0;private static int getIndex = 0;

写入队列

/**	 * 写入锁put	 */	public void put(String t) {		synchronized (full) {			while (count == items.length) {				try {					full.wait();				} catch (InterruptedException e) {					break;				}			}		}		synchronized (empty) {			items[putIndex] = t;			putIndex++;			count++;			if (putIndex == items.length) {				putIndex = 0;			}			empty.notify();		}	}

消费队列

/**	 * 消费锁	 * @return	 */	public String get() {		synchronized (empty) {			while (count == 0) {				try {					empty.wait();				} catch (InterruptedException e) {					return null;				}			}		}		synchronized (full) {			Object result = items[getIndex];			items[getIndex] = null;			getIndex++;			count--;			if (getIndex == items.length) {				getIndex = 0;			}			full.notify();			return (String) result;		}	}

这样就可以实现一个队列先进先出的功能。

原理很简单：写入队列，在写入队列是先判断队列中元素是否已满，如果满则进入等待状态；消费队列，在消费前先看下队列中是否有元素，如果有就消费，没有进入等待。和消费者生产者模式类似。

三：实现代码：

我们了解了基本的原理，现在看下jdk是如何实现的

package com.block;import java.util.concurrent.TimeUnit;import java.util.concurrent.locks.Condition;import java.util.concurrent.locks.ReentrantLock;/** * 重写ArrayBlockingQueue
    
      * @author l * * @param 
     
       */public class ArrayQueueryTest3
      
        {	private final E[] items;//数组	private final ReentrantLock lock;//锁	private final Condition notEmpty;//	private final Condition notFull;//	private int count;//总数	private int takeIndex;//	private int putIndex;//			public ArrayQueueryTest3(int capacity){		this(capacity,false);	}		public ArrayQueueryTest3(int capacity,boolean fair){		if(capacity <= 0)			throw new IllegalArgumentException();		this.items = (E[]) new Object[capacity];		lock = new ReentrantLock(fair);		notEmpty = lock.newCondition();		notFull = lock.newCondition();	}		public void put(E e) throws InterruptedException{		if(e == null) throw new NullPointerException();		final E[] items = this.items;		final ReentrantLock lock = this.lock;		lock.lockInterruptibly();				try {			try {				while(count == items.length){					notFull.await();//等待				}			} catch (Exception e2) {				notFull.signal();				throw e2;			}			insert(e);//插入队列		} finally{			lock.unlock();		}	}	private void insert(E x){		items[putIndex] = x;		putIndex = inc(putIndex);		++count;		notEmpty.signal();	}		public E take() throws InterruptedException {		final ReentrantLock lock = this.lock;		lock.lockInterruptibly();		try{			try{				while(count == 0)					notEmpty.await();//等待			}catch(InterruptedException ie){				notEmpty.signal();				throw ie;			}			E x = extract();			return x;		}finally{			lock.unlock();		}	}		public E poll(){		final ReentrantLock lock = this.lock;		lock.lock();		try {			if(count == 0)				return null;			E x = extract();			return x;		} finally {			lock.unlock();		}	}		private E extract(){		final E[] items = this.items;		E x = items[takeIndex];		items[takeIndex] = null;		takeIndex = inc(takeIndex);		--count;		notFull.signal();		return x;	}		final int inc(int i){		return (++i == items.length)? 0: i;	}		private boolean isEmpty(){		final ReentrantLock lock = this.lock;		lock.lock();		try{			return items.length == 0;		}finally{			lock.unlock();		}	}		public int size(){		final ReentrantLock lock = this.lock;		lock.lock();		try{			return count;		}finally{			lock.unlock();		}	}		public E poll(long timeout, TimeUnit unit) throws Exception{		long nanos = unit.toNanos(timeout);		final ReentrantLock lock = this.lock;		lock.lockInterruptibly();		try {			for (;;) {				if(count != 0){					E x = extract();					return x;				}				if(nanos <= 0)					return null;				try {					nanos = notEmpty.awaitNanos(nanos);//等待时长				} catch (Exception e) {					notEmpty.signal();					throw e;				}			}		} finally {			lock.unlock();		}	}		public static void main(String[] args) throws Exception {		ArrayQueueryTest3
       
         at = new ArrayQueueryTest3<>(4, false);		at.put("123");		at.put("123");		at.put("123");		System.out.println(at.size());		while(!at.isEmpty())		//如果生产者没有数据，则会一直进入等待状态，即使生产出数据，依旧会处在等待状态			System.out.println(at.take());		//每隔3s会进行一次get即使没有也会去get，当生产数据后可以依旧可以正常执行			System.out.println(at.poll(3000,TimeUnit.MILLISECONDS));			}}