leetcode 阻塞队列

package com.xkl.week2;

import java.util.concurrent.Semaphore;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

//阻塞队列,应该设计为循环队列
public class MyBlockingQueue {

    // 插入位置
    int enIndex;
    // 弹出位置
    int deIndex;

    ReentrantLock lock;
    Condition notFullCondition;
    Condition notEmptyCondition;
    //元素实际所在位置
    final Integer[] objs;
    //当前元素数量
    Integer capacity;

    //构造，初始化两个条件
    public MyBlockingQueue(int size) {
        notFullCondition = lock.newCondition();
        notEmptyCondition = lock.newCondition();
        objs = new Integer[size];

    }


    //插入元素，满则阻塞
    public void insertTail(int element) throws InterruptedException {
        try {
            //获取资源的锁
            lock.lock();
            //循环判断,满容量的时候，进入await（）；await 会释放掉锁
            while (capacity == objs.length) {
                notFullCondition.await();
            }
            objs[enIndex++] = element;
            //增加当前容量
            capacity ++;
            //唤醒非空条件
            notEmptyCondition.signalAll();
            if (enIndex >= capacity) {
                enIndex = 0;
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            //解锁
            lock.unlock();
        }
    }

    //头部弹出元素，空则阻塞，  信号量可以实现类似于条件等待的效果吗，即信号量满足的时候，则阻塞该线程，直到信号量减少，说明有新元素被插入了。
    public Integer getHead() {
        try {
            lock.lock();
            while(capacity ==0){
                notEmptyCondition.await();
            }
            Integer element = objs[deIndex];
            objs[deIndex] = null;
            deIndex ++;
            //容量减少
            capacity --;
            //唤醒 非满条件
            notFullCondition.signalAll();
            if (deIndex >= capacity) {
                deIndex = 0;
            }
            return element;
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            lock.unlock();
        }
        return null;
    }

    //判断非空
    public boolean isEmpty(){
        return capacity == 0;
    }

    //判断满了
    public boolean isFull(){
        return capacity == objs.length;
    }

}