Lock的实现类 ReentrantLock

怼烎@ 2022-12-17 11:57 145阅读 0赞

## **Lock的实现类 ReentrantLock** ##

ReentrantLock，即 可重入锁。ReentrantLock是唯一实现了Lock接口的类，并且ReentrantLock提供了更多的方法。下面通过一些实例学习如何使用 ReentrantLock

构造方法（不带参数 和带参数  true： 公平锁； false: 非公平锁）：

/**
         * Creates an instance of {@code ReentrantLock}.
         * This is equivalent to using {@code ReentrantLock(false)}.
         */
        public ReentrantLock() {
            sync = new NonfairSync();
        }
    
        /**
         * Creates an instance of {@code ReentrantLock} with the
         * given fairness policy.
         *
         * @param fair {@code true} if this lock should use a fair ordering policy
         */
        public ReentrantLock(boolean fair) {
            sync = fair ? new FairSync() : new NonfairSync();
        }

## 代码示例: ##

import java.util.concurrent.locks.Lock;  
    import java.util.concurrent.locks.ReentrantLock;
    public class LockThread {
        Lock lock = new ReentrantLock(); 
        public void lock(String name) {  
            // 获取锁  
            lock.lock();  
            try {  
                System.out.println(name + " get the lock");  
                // 访问此锁保护的资源  
            } finally {  
                // 释放锁  
                lock.unlock();  
                System.out.println(name + " release the lock");  
            }  
        }  
    
        public static void main(String[] args) {
            LockThread lt = new LockThread();  
            new Thread(() -> lt.lock("A")).start();  
            new Thread(() -> lt.lock("B")).start();  
        }
    }