1.原始构成

        Synchronized是关键字属于JVM层面，

        monitorenter（底层是通过monitor对象来完成，其实wait/notify等方法也依赖montior对象只有在同步块或方法中才能调用wait/notify等方法）

        Lock是具体类(java.util.concurrent.locks.Lock)是api层面的锁

2.使用方法

        Synchronized不需要用户去手动释放锁，当Synchronized代码执行完成后系统会自动让线程释放对锁的占用

        ReentrantLock则需要用户手动释放锁若没有主动释放锁，就有肯定导致死锁的现象。需要lock()和unlock()方法配合try/finally语句块来完成

3.等待是否可中断

        Synchronized不可以中断，除非跑出异常或者正常的运行完成

        ReentrantLock可中断，

                1).设置超时方法tryLock(long timeout,TimeUnit unit)

                2).lockInteruptibly()放代码块中，调用interupt()方法可中断

4.加锁是否公平

        Synchronized非公平锁

        ReentrantLock两者都可以，默认非公平锁。构造方法可以传boolean值，true为公平锁，false为非公平锁

5.锁绑定多个条件Condition

        Synchronized没有

        ReentrantLock用来实现分组唤醒需要唤醒的线程们，可以精确唤醒，而不是像Synchronized要么随机唤醒一个线程要么唤醒全部线程。

//案例

package register;

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

/**
 * 题目：多线程之间按顺序调用  实现A->B->C三个线程启动，要求如下：
 *      A打印5次，B打印10次，C打印15次
 *      紧接着
 *      A打印5次，B打印10次，C打印15次
 *      .....来10轮
 */
class ShareDemo{
    private int number=1;//A:1   B:2   C:3
    private Lock lock=new ReentrantLock();
    private Condition c1=lock.newCondition();
    private Condition c2=lock.newCondition();
    private Condition c3=lock.newCondition();
    public void print5(){
        lock.lock();
        try {
            //1 判断
            while (number!=1){
                c1.await();
            }
            //2 干活
            for (int i = 1; i <=5 ; i++) {
                System.out.println(Thread.currentThread().getName()+"\t "+i);
            }
            //3 通知
            number=2;
            c2.signal();
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            lock.unlock();
        }
    }

    public void print10(){
        lock.lock();
        try {
            //1 判断
            while (number!=2){
                c2.await();
            }
            //2 干活
            for (int i = 1; i <=10 ; i++) {
                System.out.println(Thread.currentThread().getName()+"\t "+i);
            }
            //3 通知
            number=3;
            c3.signal();
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            lock.unlock();
        }
    }

    public void print15(){
        lock.lock();
        try {
            //1 判断
            while (number!=3){
                c3.await();
            }
            //2 干活
            for (int i = 1; i <=15 ; i++) {
                System.out.println(Thread.currentThread().getName()+"\t "+i);
            }
            //3 通知
            number=1;
            c1.signal();
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            lock.unlock();
        }
    }
}
public class SynAndReentranLockDemo {
    public static void main(String[] args) {
        ShareDemo shareDemo=new ShareDemo();

        new Thread(()->{
            for (int i = 1; i <=10 ; i++) {
                shareDemo.print5();
            }
        },"A").start();
        new Thread(()->{
            for (int i = 1; i <=10 ; i++) {
                shareDemo.print10();
            }
        },"B").start();
        new Thread(()->{
            for (int i = 1; i <=10 ; i++) {
                shareDemo.print15();
            }
        },"C").start();
    }
}