Java多线程同步问题：信号量和Lock工具实例

原创灰太狼 2024-09-20 13:06 78阅读 0赞

在Java中，多线程同步主要依赖于两种工具：Semaphore（信号量）和ReentrantLock（可重入锁）。

1. 信号量示例：

```java
import java.util.concurrent.Semaphore;

public class SemaphoreExample {
    private final Semaphore semaphore = new Semaphore(1);

public void threadA() {
        try {
            semaphore.acquire();
            System.out.println("Thread A: Access granted.");
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

public void threadB() {
        try {
            semaphore.acquire();
            System.out.println("Thread B: Access granted.");
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        // After acquiring the lock, release it to allow other threads
        semaphore.release();
    }

public static void main(String[] args) {
        SemaphoreExample example = new SemaphoreExample();

Thread threadA = new Thread(example::threadA));
        Thread threadB = new Thread(example::threadB));

threadA.start();
        threadB.start();
    }
}
```

2. 锁工具实例：

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

public class LockExample {
    private final Lock lock = new ReentrantLock();

public void threadA() {
        try {
            // 获取锁
            lock.lock();
            System.out.println("Thread A: Lock acquired.");
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        // 使用完资源后释放锁
        lock.unlock();
    }

public void threadB() {
        try {
            // 获取锁
            lock.lock();
            System.out.println("Thread B: Lock acquired.");
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        // 与threadA类似，使用完资源后释放锁
        lock.unlock();
    }

public static void main(String[] args) {
        LockExample example = new LockExample();

Thread threadA = new Thread(example::threadA));
        Thread threadB = new Thread(example::threadB));

threadA.start();
        threadB.start();
    }
}
```

以上代码分别展示了信号量和锁工具在Java多线程同步中的使用。