package concurrent;
import java.util.concurrent.Semaphore;
/**
* 信号量,实现方法的多线程限量使用。
*/
public class SemaphoreTest extends Thread {
public static void main(String[] args) {
for (int i = 0; i <= 10; i++) {
new SemaphoreTest().start();
}
}
public void run() {
int i = 2;
OnlyTwo ot = new OnlyTwo();
while (i-- > 0) {
System.out.printf("[%3d]%d=%d\n",this.getId(),System.currentTimeMillis(),+ot.getSomthing());
try {
Thread.sleep(200);
} catch (InterruptedException e) {
e.printStackTrace();
}
ot.returnSomthing();
}
}
}
class OnlyTwo {
private static final int MAX_AVAILABLE = 3;
private static final Semaphore available = new Semaphore(MAX_AVAILABLE, false);
private static int NUM = 1;
/**
* 执行方法。
*
* @return
*/
public int getSomthing() {
try {
available.acquire();
} catch (InterruptedException e) {
e.printStackTrace();
}
return NUM++;
}
/**
* 归还
*/
public void returnSomthing() {
available.release();
}
}
运行效果
[ 9]1225837305234=1
[ 10]1225837305250=3
[ 8]1225837305250=2
[ 8]1225837305468=4
[ 10]1225837305468=6
[ 9]1225837305468=5
[ 12]1225837305250=7
[ 14]1225837305250=8
[ 16]1225837305250=9
[ 16]1225837305875=10
[ 12]1225837305875=12
[ 14]1225837305875=11
[ 18]1225837305250=13
[ 13]1225837305250=15
[ 11]1225837305250=14
[ 18]1225837306281=16
[ 13]1225837306281=18
[ 11]1225837306281=17
[ 15]1225837305250=19
[ 17]1225837305250=20
[ 17]1225837306687=21
[ 15]1225837306687=22
责任编辑：小草
