Synchronized 和 Lock区别

188 阅读1分钟

Lock锁代码:

package com.chao.demo01;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
public class SaleTicketDemo02 {
    public static void main(String[] args) {
        //并发:多线程操作同一个资源类,把资源类丢入线程
        Ticket2 ticket = new Ticket2();
        //@FunctionalInterface 函数式接口,jdk1.8 lambda表达式 (参数)->{代码}
        new Thread(()->{for (int i = 1; i < 40; i++) ticket.sale();},"A").start();
        new Thread(()->{for (int i = 1; i < 40; i++) ticket.sale();},"B").start();
        new Thread(()->{for (int i = 1; i < 40; i++) ticket.sale();},"C").start();        
    }
}
//Lock三部曲
//1. new ReentrantLock();
//2. lock.lock(); //加锁
//3. finally => lock.unlock();//解锁
class Ticket2 {
    //属性、方法
    private int number = 30;
    Lock lock = new ReentrantLock();
    public  void sale(){
        lock.lock(); //加锁

        try {
            //业务代码
            if(number>0){
                System.out.println(Thread.currentThread().getName()+"卖出了"+(number--)+"票,剩余:"+number);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.unlock();//解锁
        }
    }
}

Synchronized 和 Lock区别:

1、Synchronized内置的java关键字,Lock是一个java类

2、Synchronized 无法判断获取锁的状态,Lock可以判断是否获取到了锁

3、Synchronized 会自动释放锁,Lock必须要手动释放锁!如果不释放锁,死锁

4、Synchronized 线程1(获得锁,阻塞)、线程2(等待,傻傻的等); Lock锁就不一定会等待下去;

5、Synchronized 可重入锁,不可以中断的,非公平;Lock,可重入锁,可以判断锁,非公平(可以自己设置)

6、Synchronized 适合锁少量的代码同步问题,Lock 适合锁大量的同步代码!