boundedbuffer.java

jsp+javabean+servlet实现的在线书店

package thread;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
public class BoundedBuffer {
	static final int PutInterval=15000;
	static final int TakeInterval=40000;
	final Lock lock = new ReentrantLock();
	   final Condition notFull  = lock.newCondition(); 
	   final Condition notEmpty = lock.newCondition(); 
	   final static int BufferSize=10; 
	   final Object[] buffer = new Object[BufferSize];
	   int putptr, takeptr, count;
	   public void put(Object x) throws InterruptedException {
		   	System.out.println("put: waiting lock...");
		     lock.lock();
		     System.out.println("put: locked and wait notFull ...");
		     try {		    	 
		       while (count == buffer.length)
		         notFull.await();
		       System.out.println("put:  count="+(count+1));
		       buffer[putptr] = x;
		       if (++putptr == buffer.length) putptr = 0;
		       ++count;
		       notEmpty.signal(); 		       
		       System.out.println("Put: sleeping...");		       
		       Thread.sleep(PutInterval);
		     } 
		     finally {
		    	 lock.unlock();
		    	 System.out.println("put: unlock");
		     }
	   }
	   public Object take() throws InterruptedException {
		   System.out.println("take: waiting lock ... ");
	     lock.lock();
	     System.out.println("take: locked and wait for notEmpty ... ");
	     try {	    	 
	       while (count == 0)
	         notEmpty.await();
	       System.out.println("take:  count="+(count-1));
	       Object x = buffer[takeptr];
	       if (++takeptr == buffer.length) takeptr = 0;
	       --count;
	       notFull.signal();	      
	       System.out.println("Take: sleeping...");
	       Thread.sleep(PutInterval);
	       return x;
	     } finally {
	        lock.unlock();
	       System.out.println("take: unlock");
	     }
	   }
}