java在for循环中使用concurrent包进行多线程编程

最近在做接口的时候总是遇到一个for语句中 每次循环会涉及很多资源,包括 ftp io db,总想用现场来控制太.找到一篇文章 http://daoger.javaeye.com/blog/142485 写的不错.自己写了2个demo

1. 主线程不等待

public class CopyOfTestThreadPool {
public static void main(String args[]) throws InterruptedException {
// only two threads

ExecutorService exec = Executors.newFixedThreadPool(20);
List<Long> list = new ArrayList<Long>();
for(int index = 0; index < 1000000; index++){
list.add(System.nanoTime());
}

long start = System.currentTimeMillis();
for (Long long1 : list) {
final Long l = long1;
exec.execute(new Runnable(){

public void run() {
System.out.println(l);
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}});
}
// must shutdown
exec.shutdown();
long end = System.currentTimeMillis();
System.out.print("共计用时 ");
System.out.println(end - start);
}
}

2 主线程会等待

public class TestCountDownLatch {
public static void main(String[] args) throws InterruptedException {
long start = System.currentTimeMillis();
// 开始的倒数锁
final CountDownLatch begin = new CountDownLatch(1);
// 结束的倒数锁
final CountDownLatch end = new CountDownLatch(10000);
// 十名选手
final ExecutorService exec = Executors.newFixedThreadPool(10);
for (int index = 0; index < 10000; index++) {
final int NO = index + 1;
Runnable run = new Runnable() {
public void run() {
try {
begin.await();
Thread.sleep((long) (Math.random() * 10));
} catch (InterruptedException e) {
} finally {
end.countDown();
}
}
};
exec.submit(run);
}
System.out.println("Game Start");
begin.countDown();
end.await();
System.out.println("Game Over");
exec.shutdown();
System.out.print("共计用时 ");
System.out.println(System.currentTimeMillis() - start);
}
}

详细看上面那位老兄的blog