Java可重入锁的实现示例

package com.wnhz.lock.reentrant;

public class SychronizedDemo {

    class A {
        void a() {

        }
    }

    class B {
        void b() {
        }
    }

    public static void main(String[] args) {
        System.out.println("准备锁住class A >>>>");
        synchronized (A.class) {
            System.out.println("锁住class A--> 成功");
            System.out.println("准备再次锁住class A >>>>");
            synchronized (A.class) {
                System.out.println("锁住class A--> 成功");
            }
            System.out.println("释放class A");
        }
    }
}

package com.wnhz.lock.reentrant;

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

public class ReentrantLockDemo {

    private static final Lock lock = new ReentrantLock();
    class A {
        void a() {
        }
    }

    class B {
        void b() {
        }
    }

    public static void main(String[] args) {
        System.out.println("准备锁住class A >>>>");
        lock.lock();
        try {
            System.out.println("锁住class A--> 成功");
            System.out.println("准备再次锁住class A >>>>");
            lock.lock();
            try {
                System.out.println("锁住class A--> 成功");
            } finally {
                System.out.println("释放第二次锁住的class A");
            }
        } finally {
            lock.unlock();
            System.out.println("释放第一次锁住的Class A对象");
        }
    }
}