import java.net.InetSocketAddress;import java.nio.ByteBuffer;import java.nio.channels.SelectionKey;import java.nio.channels.Selector;import java.nio.channels.ServerSocketChannel;import java.nio.channels.SocketChannel;import java.util.Iterator;import java.util.Set;public class ServerChannelTest{    public static void main(String[] args)    {	new ServerChannelTest().listen();    }    public void listen()    {	try	{	    ByteBuffer bb = ByteBuffer.allocate(1024);				    ServerSocketChannel ssc = ServerSocketChannel.open();	    ssc.socket().bind(new InetSocketAddress(10011));//绑定端口10011，wildcard ip	    ssc.configureBlocking(false);// 设置为非阻塞	    Selector selector = Selector.open();	    ssc.register(selector, SelectionKey.OP_ACCEPT);// 注册监听	    debug("注册监听成功！");				    while (true)	    {		Thread.sleep(1000);// 为了方便看到输出。						debug("检测是否有SelectionKey，并且select");					if (selector.select(1000) <= 0)// 设置timeout为1秒，否则会阻塞在select() 		{			continue;		}// 没有事件被选中						Set
    
      set = selector.selectedKeys();		Iterator
     
       it = set.iterator();		while (it.hasNext())		{		    SelectionKey key = it.next();							    debug("取出SelectedKeys");		    if (key.isAcceptable())		    {			debug("ACCEPT key");			ServerSocketChannel ssChannel = (ServerSocketChannel)key.channel();			SocketChannel sc = ssChannel.accept();// accept a connection			// 重要！否则抛出java.nio.channels.IllegalBlockingModeException。                        // 要与ServerSocketChannel一致。			sc.configureBlocking(false);				// 注意！不要注册SelectionKey.OP_WRITE.否则每次都能select到它，性能降低。//			sc.register(selector, SelectionKey.OP_READ | SelectionKey.OP_WRITE);			sc.register(selector, SelectionKey.OP_READ);		    }		    else if (key.isReadable())		    {			debug("READ key");			SocketChannel sc = (SocketChannel)key.channel();			bb.clear();			if (sc.read(bb) < 0)			{			    // read()返回-1表明到达输入流尾。经验证也就是客户端断开了连接。			    System.out.println("客户端断开了连接");			    sc.close();			    break;			}			bb.flip();			System.out.println(bb.get(0));		    }//		    else if (key.isWritable())//		    {//		        debug("WRITE key");//		    }// 每次都会取得WRITE key,即使你 不需要。							    it.remove();//删除处理过的key	        }	    }	}	catch (Exception e)	{	     e.printStackTrace();	}    }    public static void debug(String str)    {	System.out.println(str);    }}