柵欄類似閉鎖,但是它們是有區別的.
1.閉鎖用來等待事件，而柵欄用于等待其他線程.什么意思呢?就是說閉鎖用來等待的事件就是countDown事件,只有該countDown事件執行后所有之前在等待的線程才有可能繼續執行;而柵欄沒有類似countDown事件控制線程的執行,只有線程的await方法能控制等待的線程執行.
2.CyclicBarrier強調的是n個線程，大家相互等待，只要有一個沒完成，所有人都得等著。
場景分析:10個人去春游,規定達到一個地點后才能繼續前行.代碼如下
import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;
class CyclicBarrierWorker implements Runnable {
private int id;
private CyclicBarrier barrier;
public CyclicBarrierWorker(int id, final CyclicBarrier barrier) {
this.id = id;
this.barrier = barrier;
}
@Override
public void run() {
// TODO Auto-generated method stub
try {
System.out.println(id + " th people wait");
barrier.await(); // 大家等待最后一個線程到達
} catch (InterruptedException | BrokenBarrierException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
public class TestCyclicBarrier {
public static void main(String[] args) {
int num = 10;
CyclicBarrier barrier = new CyclicBarrier(num, new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
System.out.println("go on together!");
}
});
for (int i = 1; i <= num; i++) {
new Thread(new CyclicBarrierWorker(i, barrier)).start();
}
}
}
輸出
1 th people wait
2 th people wait
3 th people wait
4 th people wait
5 th people wait
7 th people wait
8 th people wait
6 th people wait
9 th people wait
10 th people wait
go on together!
