版权声明:尊重原创,码字不易,转载需博主同意。 https://blog.csdn.net/qq_34626097/article/details/88935136
Condition
- Condition 接口描述了可能会与锁有关联的条件变量。这些变量在用法上与使用Object.wait 访问的隐式监视器类似,但提供了更强大的功能。需要特别指出的是,当个Lock可能与多个Condition对象相关联。为了避免兼容性问题,Condition方法的名称与对应的Object版本不同。
- 在Condition 对象中,与wait、notify 和 notifyAll 方法对应的是 await、signal 和 signalAll。
- Condition 实例实质上被绑定到一个锁上。要为特定Lock实例获得Condition实例,请使用其NewCondition()方法。
代码demo
/*
*虚假唤醒
*/
public class TestProductorAndConsumerForLock {
public static void main(String[] args) {
Clerk clerk = new Clerk();
Productor pro = new Productor(clerk);
Consumer cus = new Consumer(clerk);
new Thread(pro,"生产者A").start();
new Thread(pro,"生产者D").start();
new Thread(cus,"消费者C").start();
new Thread(cus,"消费者F").start();
}
}
//销售员
class Clerk{
private int product = 0 ;
private Lock lock = new ReentrantLock();
private Condition conditioin = lock.newCondition();
//进货
public void get() {
lock.lock();
try {
while(product >= 1) {//为了解决虚假唤醒问题,应该总是使用在循环中
System.out.println("产品已经满了");
try {
conditioin.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println(Thread.currentThread().getName()+ " : " + ++product);
conditioin.signalAll();
} finally {
lock.unlock();
}
}
//出售
public void sale() {
lock.lock();
try {
while(product <= 0) {
System.out.println("缺货");
try {
conditioin.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println(Thread.currentThread().getName() + " : " + --product);
conditioin.signalAll();
} finally {
lock.unlock();
}
}
}
//生产者
class Productor implements Runnable{
private Clerk clerk;
public Productor(Clerk clerk) {
super();
this.clerk = clerk;
}
@Override
public void run() {
for (int i = 0; i < 20; i++) {
clerk.get();
}
}
}
//消费者
class Consumer implements Runnable {
private Clerk clerk;
public Consumer(Clerk clerk) {
super();
this.clerk = clerk;
}
@Override
public void run() {
for (int i = 0; i < 20; i++) {
try {
Thread.sleep(200);
} catch (InterruptedException e) {
e.printStackTrace();
}
clerk.sale();
}
}
}