synchronized:隐式锁
jdk 1.5 后,同步锁 Lock
- 同步锁 Lock是一个显示锁,需要通过 lock() 方法上锁,必须通过 unlock() 方法进行释放锁。
示例代码:
public class TestLock {
public static void main(String[] args) {
Ticket ticket = new Ticket();
new Thread(ticket, "1号窗口").start();
new Thread(ticket, "2号窗口").start();
new Thread(ticket, "3号窗口").start();
}
}
class Ticket implements Runnable{
private int tick = 100;
private Lock lock = new ReentrantLock();
@Override
public void run() {
while(true){
lock.lock(); //上锁
try{
if(tick > 0){
try {
Thread.sleep(20);
} catch (InterruptedException e) {
}
System.out.println(Thread.currentThread().getName() + " 完成售票,余票为:" + --tick);
}else {
break;
}
}finally{
lock.unlock(); //释放锁
}
}
}
}