java中的加鎖機制-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提供了多線程的升級解決方法（顯示的鎖機制）
         *  將同步synchronized替換成了顯示的Lock操作----》lock()  unlock()
         *  將Object中的wait、notify/notifyAll  替換成了 Condition (await/signal/signalAll)
         *  該對象可以 Lock.newCondition() 獲取
         *  一個鎖可以綁定多個condition對象，避免了因同步嵌套導致死鎖問題的發生。
         *     釋放鎖的操作必須放在我們的try/finally代碼塊或者try..catch/finally代碼塊當中使用
         * 
         *     實現了本方只喚醒對方的操作！
         * 
         * */
        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()+"生產者生產的..."+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()+"消費者消費的.........."+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();
            } 
        }
    }
}