阻塞队列实现

class MyBlockingQueue {
    private String[] elems = null;
    private int head = 0;
    private int tail = 0;
    private int size = 0;
    private Object locker = new Object();//锁对象
    
    public MyBlockingQueue(int capacity) {
        elems = new String[capacity];
    }
    
    public void put(String elem) throws InterruptedException {
        synchronized (locker) {
            while (size >= elems.length) {
                //队列满了,产生阻塞
                locker.wait();
            }
            elems[tail] = elem;
            tail ++;
            if (tail >= elems.length) { //循环队列
                tail = 0;
            }
            size ++;
            locker.notify(); //入队之后重新唤醒
        }
    }
    
    public String take() throws InterruptedException {
        String elem = null;
        synchronized (locker) {
            while (size == 0) {
                locker.wait();//队列空了,产生阻塞
            }
            elem = elems[head];
            head ++;
            if (head >= elems.length) {
                head = 0;
            }
            size --;
            locker.notify();//元素出队列之后, 唤醒
        }
        return elem;
    }
}