java中的加锁机制-Lock

package procus2;

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

public class ProduceCosumer {
public static void main(String[] args) {
/*
*  jdk1.5提供了多线程的升级解决方法（显示的锁机制）
*  将同步synchronized替换成了显示的Lock操作----》lock()  unlock()
*  将Object中的wait、notify/notifyAll  替换成了 Condition (await/signal/signalAll)
*  该对象可以 Lock.newCondition() 获取
*  一个锁可以绑定多个condition对象，避免了因同步嵌套导致死锁问题的发生。
*     释放锁的操作必须放在我们的try/finally代码块或者try..catch/finally代码块当中使用
*
*     实现了本方只唤醒对方的操作！
*
* */
Resource r = new Resource();
Product product = new Product(r);
Customer customer = new Customer(r);
Thread t1 = new Thread(product);
Thread t2 = new Thread(product);
Thread t3 = new Thread(customer);
Thread t4 = new Thread(customer);
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_cus = 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()+"生产者生产的..."+this.name);
flag = true;
condition_cus.signal();
} finally {
lock.unlock();
}

}
public void get() throws InterruptedException{
lock.lock();
try {
while(!flag){
condition_cus.await();
}
System.out.println(Thread.currentThread().getName()+"消费者消费的.........."+this.name);
flag = false;
condition_pro.signal();
} finally {
lock.unlock();
}
}
}
class Product implements Runnable{
private Resource resource;
public Product(Resource r) {
this.resource = r;
}
public void run(){
while(true){
try {
resource.set("【商品】");
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
class Customer implements Runnable{
private Resource resource;
public Customer(Resource r) {
this.resource = r;
}
@Override
public void run() {
while(true){
try {
resource.get();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}