并发同步与锁

1.一个生产者和一个消费者。
存在资源竞争情况：1).生产者和消费者同时访问fuilt store，当时fuilt store库存为0时，生产者生产一个产品，但未修改库存数量时，消费者这时访问fuilt store发现库存数量为0，无法购买产品；当fuilt store库存为100时，消费者购买一个产品后，未来得及修改库存数量，生产者这时访问fuilt store发现库存满了，不在生产产品。  

这种资源竞争的情况，还不算糟糕，虽然造成了某一次的判断错误，但并没有影响整体业务功能。

class  FuiltStore {
	public int curFuiltNum = 0;
	public boolean increase()
	{
		if (curFuiltNum < 100) {
		    this.curFuiltNum++;
		    return true;
		}
		return false;
	}
	public boolean decrease()
	{
		if (curFuiltNum > 0) {
		    this.curFuiltNum--;
		    return true;
		}
		return false;
	}
}

class FuiltWorkerTom implements Runnable{
	private FuiltStore fuiltStore;
	private int stockNum = 0;
	public FuiltWorkerTom(FuiltStore fuiltStore)
	{
		this.fuiltStore = fuiltStore;
	}
	public boolean stockFuilt() {
		if (this.fuiltStore.increase())
		{
			System.out.println("stock");
			return true;
		}
		return false;
	}
	@Override
	public void run() {
		while (this.stockNum < 100) {
			if (this.stockFuilt()) {
				this.stockNum++;
				Thread.yield();
			}
		}
	}
}
class FuiltBuyerMary implements Runnable{
	private FuiltStore fuiltStore;
	private int buyNum = 0;
	public FuiltBuyerMary(FuiltStore fuiltStore)
	{
		this.fuiltStore = fuiltStore;
	}
	public boolean buyFuilt() {
		if (this.fuiltStore.decrease()) {
			System.out.println("buy");
			return true;
		}
		return false;
	}
	@Override
	public void run() {
		while (this.buyNum < 100) {
			if (this.buyFuilt()) {
				this.buyNum++;
			    Thread.yield();
			}
		}
	}
}
public class MainThread {

	public static void main(String[] args) {
		FuiltStore fuiltStore = new FuiltStore();
        Thread fuiltWorkerTom = new Thread(new FuiltWorkerTom(fuiltStore));
        fuiltWorkerTom.start();
        Thread fuiltBuyerMary = new Thread(new FuiltBuyerMary(fuiltStore));
        fuiltBuyerMary.start();
        try {
			fuiltWorkerTom.join();
	        fuiltBuyerMary.join();
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
        System.out.println(fuiltStore.curFuiltNum);  
	}

}

并发同步与锁

原文：http://blog.csdn.net/guoguo11191/article/details/44263007