015.1 Lock接口

内容：Lock接口使用步骤，同步生产大白兔奶糖的例子

同步代码块的锁是隐式的，显式容易让我们理解。所以我们使用这个显式的方法，方便理解代码。
######实现同步步骤：
1、获取锁：lock()
2、同步代码
3、释放锁：unlock()
但是同步代码可能出现异常，所以需要使用try{}finally{}

例子代码：

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

public class NewProducerConsumer
{

    public static void main(String[] args)
    {
        Res r = new Res();
        Producer producer = new Producer(r);
        Consumer consumer = new Consumer(r);
        Thread t0 = new Thread(producer);
        Thread t1 = new Thread(producer);
        Thread t2 = new Thread(consumer);
        Thread t3 = new Thread(consumer);
        t0.start();
        t1.start();
        t2.start();
        t3.start();
    }
}

class Res{
    private String name;
    private int count;
    private boolean flag = false;
    Lock lock = new ReentrantLock();   //产生一个锁
    public void set(String name)                   //Res的set方法和get方法是用的是同一个锁，所以同一个对象两个方法只会执行一个方法
    {
        lock.lock();   //获取锁
        try{
            while(flag){
                try {
                    wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            this.name = name + "--" + count;
            count++;
            System.out.println(Thread.currentThread().getName()+"____生产者______"+this.name);
            flag = true;
            notifyAll();
        }
        finally{
            lock.unlock();    //释放锁
        }
    }
    public void get()
    {
        lock.lock();
        try{
            while(!flag){
                try {
                    wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            System.out.println(Thread.currentThread().getName()+"....消费者。。。。"+this.name);
            flag = false;
            notifyAll();
        }
        finally{
            lock.unlock();
        }
    }
}

class Producer implements Runnable{
    private Res r;
    public Producer(Res r) {
        this.r = r;
    }
    public void run()
    {
        int i = 0;
        while(i<100){
            r.set("大白兔奶糖");
            i++;
        }
    }
}


class Consumer implements Runnable{
    private Res r;
    public Consumer(Res r) {
        this.r = r;
    }
    public void run()
    {
        int i = 0;
        while(i<100){
            r.get();
            i++;
        }
    }
}

如果看不懂例子，欢迎提问