1.重入锁和synchronized比较
| 特征 | synchronized | reentrantLock |
| 底层原理 | JVM实现 | JDK实现 |
| 性能区别 | 低->高（JDK5+） | 高 |
| 锁的释放 | 自动释放（编译器保证） | 手动释放（finally保证） |
| 编码程度 | 简单 | 复杂 |
| 锁的粒度 | 读写不区分 | 读锁、写锁 |
| 高级功能 | 无 |
公平锁、非公平锁唤醒 Condition分组唤醒 中断等待锁 |
2.代码
public static int users = 100;
public static int downTotal = 50000;
public static int count = 0;
private static ReentrantLock lock = new ReentrantLock();
public static void main(String[] args) {
ExecutorService executorService = Executors.newCachedThreadPool();
final Semaphore semaphore = new Semaphore(users);
for (int i = 0; i < downTotal; i++) {
executorService.execute(new Runnable() {
@Override
public void run() {
try {
semaphore.acquire();
add();
semaphore.release();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
});
}
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("下载总数为："+count);
}
private static void add() {
lock.lock();
try {
count++;
} finally {
lock.unlock();//一定要放在finally中，防止死锁
}
}
标签：重入,int,lock,ReentrantLock,finally,static,public From： https://www.cnblogs.com/blanset/p/16785852.html