只唤醒对方

package comm;

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

public class ProducerConsumerDemo2 {

public static void main(String[] args) {
Resource r = new Resource();
Producer pro = new Producer(r);
Consumer con = new Consumer(r);

Thread t1 = new Thread(pro);
Thread t2 = new Thread(pro);
Thread t3 = new Thread(con);
Thread t4 = new Thread(con);

t1.start();
t2.start();
t3.start();
t4.start();

}
}

class Resource {
private String name;
private int count = 1;
private boolean flag = false;

private Lock lock = new ReentrantLock();
private Condition condition_pro = lock.newCondition();
private Condition condition_con = lock.newCondition();

public void set(String name) throws InterruptedException {

lock.lock();
try {
while (flag)
condition_pro.await();
this.name = name + "==" + (count++);
System.out.println(Thread.currentThread().getName()
+ "==producer==" + this.name);
flag = true;
condition_con.signal(); // 唤醒对方
} finally {
lock.unlock();
}
}

public void out() throws InterruptedException {
lock.lock();
try {
while (!flag)
condition_con.await();
System.out.println(Thread.currentThread().getName()
+ "====consumer====" + this.name);
flag = false;
condition_pro.signal(); // 唤醒对方
} finally {
lock.unlock();
}
}
}

class Producer implements Runnable {
private Resource res;

Producer(Resource res) {
this.res = res;
}

public void run() {
while (true) {
try {
res.set("+商品+");
} catch (InterruptedException e) {
}
}
}
}

class Consumer implements Runnable {
private Resource res;

Consumer(Resource res) {
this.res = res;
}

public void run() {
while (true)
try {
res.out();
} catch (InterruptedException e) {
}
}
}