捕获用户按键"Ctrl+C"

  在Console下，用户按下Ctrl+C后，进程就会收到相应的中断信号(Signal). 然后，该进程就会作手处理(或默认不处理)。

  下面，看看Java中怎么处理用户按下Ctrl+C(linux下 kill -15 pid也可).

	public static void hookBySignal(){
		  SignalHandler handler = new SignalHandler(){
			public void handle(Signal sig) { 
				System.out.println("hooking shutdown signal");
			} };
			Signal.handle(new Signal("INT"),handler);
			//hook ctrl+c
			Signal.handle(new Signal("TERM"),handler);
			//hook alt+f4 
	}

备注： 上面是引用sun.misc Package下的Class,非Sun的JVM,可能就不适用。


再来看看Jetty 是怎么处理这类的?

/* ------------------------------------------------------------ */
    /* ------------------------------------------------------------ */
    /* ------------------------------------------------------------ */
    /**
     * ShutdownHook thread for stopping all servers.
     * 
     * Thread is hooked first time list of servers is changed.
     */
    private static class ShutdownHookThread extends Thread
    {
        private boolean hooked = false;
        private ArrayList servers = new ArrayList();

        /**
         * Hooks this thread for shutdown.
         * 
         * @see java.lang.Runtime#addShutdownHook(java.lang.Thread)
         */
        private void createShutdownHook()
        {
            if (!Boolean.getBoolean("JETTY_NO_SHUTDOWN_HOOK") && !hooked)
            {
                try
                {
                    Method shutdownHook = java.lang.Runtime.class.getMethod("addShutdownHook", new Class[]
                    { java.lang.Thread.class});
                    shutdownHook.invoke(Runtime.getRuntime(), new Object[]
                    { this});
                    this.hooked = true;
                }
                catch (Exception e)
                {
                    if (Log.isDebugEnabled())
                        Log.debug("No shutdown hook in JVM ", e);
                }
            }
        }

        /**
         * Add Server to servers list.
         */
        public boolean add(Server server)
        {
            createShutdownHook();
            return this.servers.add(server);
        }

        /**
         * Contains Server in servers list?
         */
        public boolean contains(Server server)
        {
            return this.servers.contains(server);
        }

        /**
         * Append all Servers from Collection
         */
        public boolean addAll(Collection c)
        {
            createShutdownHook();
            return this.servers.addAll(c);
        }

        /**
         * Clear list of Servers.
         */
        public void clear()
        {
            createShutdownHook();
            this.servers.clear();
        }

        /**
         * Remove Server from list.
         */
        public boolean remove(Server server)
        {
            createShutdownHook();
            return this.servers.remove(server);
        }

        /**
         * Remove all Servers in Collection from list.
         */
        public boolean removeAll(Collection c)
        {
            createShutdownHook();
            return this.servers.removeAll(c);
        }

        /**
         * Stop all Servers in list.
         */
        public void run()
        {
            setName("Shutdown");
            Log.info("Shutdown hook executing");
            Iterator it = servers.iterator();
            while (it.hasNext())
            {
                Server svr = (Server) it.next();
                if (svr == null)
                    continue;
                try
                {
                    svr.stop();
                }
                catch (Exception e)
                {
                    Log.warn(e);
                }
                Log.info("Shutdown hook complete");

                // Try to avoid JVM crash
                try
                {
                    Thread.sleep(1000);
                }
                catch (Exception e)
                {
                    Log.warn(e);
                }
            }
        }
    }
	

注意到他为什么要使用反射，而不直接使用java.lang.Runtime.addShutdownHook ?
仔细想一下，应该主要是考虑到jdk版本兼容问题(低版本1.2.2下不被支持)。


再贴上java.lang.Runtime#addShutdownHook的注释