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.iteye.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