标签：.exe pre nal 使用 thread next long down 执行
java.util.concurrency中的CountDownLatch，主要用于等待一个或多个其他线程完成任务。CountDownLatch在初始化时，会被赋一个整数，每次执行countDown()方法，该整数都会减一，直至到0，这一过程不可逆转。其await()方法会在该整数不为0时当前线程阻塞，为0时当前线程进行下去。阻塞时，其他线程得到执行。
下面是一个普通的案例：
Player
import java.util.Random;
import java.util.concurrent.CountDownLatch;
public class Player implements Runnable {
private CountDownLatch begin;
private CountDownLatch end;
private String playerNO;
public Player(String playerNO, CountDownLatch begin, CountDownLatch end) {
this.playerNO = playerNO;
this.begin = begin;
this.end = end;
}
@Override
public void run() {
// 等待枪响
try {
begin.await();
long timeUsed = new Random().nextInt(10000);
Thread.sleep(timeUsed);
System.out.println("运动员" + playerNO + "耗时" + timeUsed + "完成比赛");
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
end.countDown();
}
}
}
OlympicsGame
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class OlympicsGame {
private static final int PLAYER_SIZE = 5;
private CountDownLatch begin;
private CountDownLatch end;
public CountDownLatch getBegin() {
return begin;
}
public void setBegin(CountDownLatch begin) {
this.begin = begin;
}
public CountDownLatch getEnd() {
return end;
}
public void setEnd(CountDownLatch end) {
this.end = end;
}
public OlympicsGame() {
begin = new CountDownLatch(1);
end = new CountDownLatch(PLAYER_SIZE);
}
public static void main(String[] args) {
// 举办一场比赛
OlympicsGame olympic = new OlympicsGame();
// 设定比赛开始，枪声
CountDownLatch begin = olympic.getBegin();
// 所有运动员结束比赛，才算结束比赛
CountDownLatch end = olympic.getEnd();
// 运动员进场，并编号,等待枪响
Player[] players = new Player[PLAYER_SIZE];
ExecutorService ex = Executors.newFixedThreadPool(PLAYER_SIZE);
for (int i = 0; i < 5; i++) {
players[i] = new Player("NO" + (i + 1), begin, end);
ex.submit(players[i]);
}
// 枪响
begin.countDown();
try {
// 等待所有运动员到达终点
end.await();
System.out.println("比赛结束，所有运动员完成比赛");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
某次执行结果是：
标签：.exe pre nal 使用 thread next long down 执行
原文地址：http://www.cnblogs.com/ecoowu/p/java-util-concurrency-CountDownLatch.html
