Java 基于AQS实现一个同步器

package com.example.demo.Lock;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.AbstractQueuedSynchronizer;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;

public class MyNonLock implements Lock, java.io.Serializable {
 
 //创建一个具体的MySync来做具体的工作
 private final MySync mySync = new MySync();

 @Override
 public void lock() {
 mySync.acquire(1);
 }

 @Override
 public boolean tryLock() {
 return mySync.tryAcquire(1);
 }
 
 @Override
 public boolean tryLock(long time, TimeUnit unit) throws InterruptedException {
 return mySync.tryAcquireNanos(1, unit.toNanos(time));
 
 }
 
 //带了Interruptibly的方法表示对中断进行响应，就是当一个线程在阻塞队列中被挂起的时候，
 //其他线程调用该线程的中断方法中断了该线程，该线程会抛出InterruptedException异常
 @Override
 public void lockInterruptibly() throws InterruptedException {
  mySync.acquireInterruptibly(1);
 }

 @Override
 public void unlock() {
 mySync.release(1);
 }

 //很方便的获取条件变量
 @Override
 public Condition newCondition() {
 return mySync.newCondition();
 }
 
 

 private static class MySync extends AbstractQueuedSynchronizer {

 // 锁是否已经被持有
 protected boolean isHeldExclusively() {
  return getState() == 1;
 }

 // 如果state为0，就尝试获取锁，将state修改为1
 public boolean tryAcquire(int acquires) {
  assert acquires == 1;
  if (compareAndSetState(0, 1)) {
  setExclusiveOwnerThread(Thread.currentThread());
  return true;
  }
  return false;
 }

 // 尝试释放锁，将state设置为0
 protected boolean tryRelease(int releases) {
  assert releases == 1;
  if (getState() == 0) {
  throw new IllegalMonitorStateException();
  }
  setExclusiveOwnerThread(null);
  setState(0);
  return true;
 }

 //提供条件变量接口
 Condition newCondition() {
  return new ConditionObject();
 }
 }

}

package com.example.demo.study;

import java.util.Queue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.locks.Condition;

import com.example.demo.Lock.MyNonLock;

public class Study0202 {
 // 我们往这个队列中添加字符串
 final static Queue<String> queue = new LinkedBlockingQueue<String>();
 // 创建我们自己的锁对象
 final static MyNonLock lock = new MyNonLock();
 // 当队列queue中字符串满了，其他的生产线程就丢到这个条件队列里面
 final static Condition full = lock.newCondition();
 // 当队列queue是空的，其余的消费线程就丢到这个条件队列里面
 final static Condition empty = lock.newCondition();
 // 队列queue中存字符串最多只能是3个
 final static int queue_MAX_SIZE = 3;

 //往队列queue中压入字符串
 public static void add() {
 lock.lock();
 try {
  // 当队列满了，就将其他生产线程丢进full的条件队列中
  while (queue.size() == queue_MAX_SIZE) {
  full.await();
  }
  System.out.println("prd:" + "hello");
  // 往队列queue中添加字符串
  queue.add("hello");
  // 生产成功，唤醒消费条件队列中的所有线程赶紧去消费
  empty.signalAll();
 } catch (Exception e) {
  //
 } finally {
  lock.unlock();
 }
 }

 //从队列queue弹出字符串
 public static void poll() {
 lock.lock();
 try {
  // 当队列queue中一个字符串都没有，就将剩下的消费线程丢进enpty对应的队列中
  while (queue.size() == 0) {
  empty.await();
  }
  // 消费队列queue中的字符串
  String poll = queue.poll();
  System.out.println("consumer:" + poll);
  // 消费成功，就唤醒full中所有的生产线程去生产字符串
  full.signalAll();
 } catch (Exception e) {
  //
 } finally {
  lock.unlock();
 }
 }

 public static void main(String[] args) {
 // 生产者线程
 for (int i = 0; i < 5; i++) {
  new Thread(() -> {
  add();
  }).start();
 }

 // 消费者线程
 for (int i = 0; i < 5; i++) {
  new Thread(() -> {
  poll();
  }).start();
 }
 }
}