学习笔记——多线程间的通信

黄兴旺

练习：生产者消费者。
这里面最主要的知识点是：另外一种线程间的通信，另外一种锁的表达。
import java.util.concurrent.locks.*;
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();//将同步替换成了lock操作。
  try
  {
while(flag)   //定义while判断标记是因为要让被唤醒的线程再一次判断标记。
condition_pro.await();
this.name = name+"--"+count++;
System.out.println(Thread.currentThread().getName()+"....生产者...."+this.name);
flag = true;
condition_con.signal();//实现了本方只唤醒对方的操作。
  }
  finally
  {
lock.unlock();//释放锁的动作一定要执行。
  }
}
public  void out()throws InterruptedException
{
  lock.lock();
  try
  {
while(!flag)
condition_con.await();
System.out.println(Thread.currentThread().getName()+"....消费者..........."+this.name);
flag = false;
condition_pro.signal();
  }
  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)
{
}
  }
}
}

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学习笔记——多线程间的通信

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