之前在测试多线程发送邮件时，使用junit发现，junit在调用待测试的类的方法创建子线程处理任务，在主线程跳出该类方法回到junit test方法时，jvm被终止，所有还在处理任务的子线程都被关闭。
此时，可以用调用CountDownLatch类来进行子线程计数，子线程运行完时调用countDown()使计数减1，在主线程调用await()阻塞等待子线程全部处理完再返回junit test
代码如下：
/** * * @Title: sendTest * @Desc: junit测试 多线程发送多封邮件 * */ @Test public void sendTest() { MyMail mm = new MyMail(); List<MailParam> mails = new ArrayList<>(); for (int i = 20; i > 0; i--) { MailParam mail = new MailParam(); mail.setHost("smtp.163.com"); mail.setPort(25); mail.setUser("xxx.com"); mail.setPassword("*****"); mail.setFrom("xxx@163.com"); mail.setTo(TO); mail.setAgreement("smtp"); mail.setSSL(false); mail.setSubject("呵呵"); mail.setContant("23333333333333333"); mails.add(mail); } mm.doWorks(mails, SEND); } /** * * @Title: doWork * @Desc: 邮件工作开始,批量,多线程 * * @param mail * @param type * 0：发送邮件 ； 1：接收邮件 * */ public void doWorks(List<MailParam> mails, int type) { CountDownLatch count = new CountDownLatch(mails.size());//设置子线程数目 for (MailParam mail : mails) { new Thread(new MailThread(mail, type, count)).start(); try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } } try { count.await();//等待子线程全部运行完 } catch (InterruptedException e) { e.printStackTrace(); } } /** * @Title: MailThread.java * @desc: 邮件线程类 * @author mengchuan.li */ class MailThread implements Runnable { private MailParam mail; private int type; private CountDownLatch count; public MailThread(MailParam mail, int type, CountDownLatch count) { this.mail = mail; this.type = type; this.count = count; } @Override public void run() { new MyMail().doWork(mail, type); if (count != null) { count.countDown();//计数减1 } } }