锁的理解

   /**
     * 公平锁 非公平锁
     * 公平锁 非常公平 不可以插队
     * 非公平锁 可以插队
     */

公平锁非公平锁.png

/**
    * 可重入锁  递归锁
    * 
    */

//方式一
/**
 * @Author: wz
 * @Date: 2022/7/12 23:23
 */
public class lock {
    /**
     *  可重入锁
     */

    public static void main(String[] args) {
        Phone phone = new Phone();

        new Thread(()->{
            phone.sms();
        },"A").start();

        new Thread(()->{
            phone.sms();
        },"B").start();

    }
}
class Phone {
    public synchronized  void sms(){
        System.out.println(Thread.currentThread().getName()+"sms");
        call();
    }

    public synchronized  void call(){
        System.out.println(Thread.currentThread().getName()+"call");
    }
}

// 方式二
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 * @Author: wz
 * @Date: 2022/7/12 23:23
 */
public class lock2 {
    /**
     * 可重入锁
     */

    public static void main(String[] args) {
        Phone2 phone = new Phone2();

        new Thread(() -> {
            phone.sms();
        }, "A").start();

        new Thread(() -> {
            phone.sms();
        }, "B").start();

    }
}

class Phone2 {
    Lock lock = new ReentrantLock();

    public void sms() {
        lock.lock();
        try {
            System.out.println(Thread.currentThread().getName() + "sms");
            call();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }


    }

    public void call() {
        lock.lock();
        try {
            System.out.println(Thread.currentThread().getName() + "call");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }
}