问JVM如何终止守护进程线程？或者如何编写优雅终止的守护进程线程

EN

public class DaemonThreadPlay {
    public static void main(String [] args) {
        Thread daemonThread = new Thread() {
            public void run() {
                while (true) {
                    try {
                        System.out.println("Try block executed");
                        Thread.sleep(1000l);
                    } catch (Throwable t) {
                        t.printStackTrace();
                    }
                }
            }

            @Override
            public void finalize() {
                System.out.println("Finalize method called");
            }
        };
        daemonThread.setDaemon(true);
        daemonThread.start();

        try {
            Thread.sleep(2500l);
        } catch (Throwable t) {
            //NO-OP
        }
    }
}    

Thread shutdownHook = ... // construct thread that somehow
                          // knows about all the daemon threads
Runtime.getRuntime().addShutdownHook(shutdownHook);

ExecutorService execPool = Executors.newSingleThreadExecutor(new ThreadFactory() {

    @Override    
    public Thread newThread(Runnable runnable) {       
         Thread thread = Executors.defaultThreadFactory().newThread(runnable);
         thread.setDaemon(true);
         return thread;    
    } 
}); 

Runtime.getRuntime().addShutdownHook(....)