如果是web项目，会启动端口监听，主线程阻塞不会退出。但如果是普通的java项目对外提供服务，主线程一旦跑完，整个进程就退出了。
之前见过有使用死循环方式来防止退出的。着实捏了把冷汗，这会导致cpu占用变高。那有没有更优雅的方式呢，我从阿里开源RPC框架dubbo中找到了答案
public class StartMain {
private static final ReentrantLock LOCK = new ReentrantLock();
private static final Condition STOP = LOCK.newCondition();
public static void main(String[] args) {
AbstractApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
applicationContext.start();
logger.info("service start success !~");
addHook(applicationContext);
//主线程阻塞等待，守护线程释放锁后退出
try {
LOCK.lock();
STOP.await();
} catch (InterruptedException e) {
logger.warn(" service stopped, interrupted by other thread!", e);
} finally {
LOCK.unlock();
}
}
/**
* Created on 2017年12月12日
* <p>
* Discription:[添加一个守护线程]
*
* @param applicationContext
*
*/
private static void addHook(AbstractApplicationContext applicationContext) {
Runtime.getRuntime().addShutdownHook(new Thread(() -> {
try {
applicationContext.stop();
} catch (Exception e) {
logger.error("StartMain stop exception ", e);
}
logger.info("jvm exit, all service stopped.");
try {
LOCK.lock();
STOP.signal();
} finally {
LOCK.unlock();
}
}, "StartMain-shutdown-hook"));
}
}
