代码非常短，注释都在代码里了，相信都能理解

package com.rock.nio;import java.net.InetSocketAddress;import java.nio.ByteBuffer;import java.nio.channels.SelectionKey;import java.nio.channels.Selector;import java.nio.channels.SocketChannel;import java.util.Iterator;import java.util.Set;public class NioHttp2 {	public static void main(String[] args) throws Exception {				Selector selector = Selector.open();		InetSocketAddress remoteAddress = new InetSocketAddress("chushu.la", 80);		// 调用open的静态方法创建连接指定的主机的SocketChannel		SocketChannel socketChangel = SocketChannel.open(remoteAddress);		// 设置该sc已非阻塞的方式工作		socketChangel.configureBlocking(false);		// 将SocketChannel对象注册到指定的Selector		socketChangel.register(selector, SelectionKey.OP_READ);		sendMessage(socketChangel, createHttpMsg()); 				boolean remoteConnClosed = false;		while (!remoteConnClosed) {			int n = selector.select(1000*60);//设置超时为1分钟			if (n <= 0) {				break;//			}			Set
    
      selectedKeys = selector.selectedKeys();			Iterator
     
       iter = selectedKeys.iterator();			while (iter.hasNext()) {				SelectionKey key = iter.next();				if (key.isReadable()) {					ByteBuffer buffer = ByteBuffer.allocate(1024);//如果读取的数据大于1024, 则下次调用 selector.select 的数值还会大于0					SocketChannel client = (SocketChannel) key.channel();					int num = client.read(buffer);					while(num > 0){//如果num = 0, 表示读取不到远端数据，可能是远端网速慢或者其他网络原因， 下次selector.select返回时可再读; 如果num=-1,表示远端关闭了连接。						client.read(buffer);						String reString = new String(buffer.array(), "utf-8");						System.out.print(reString);						num = client.read(buffer);					}										if(num == -1){//远程连接主动关闭						System.out.println("remote server close connection~~");						client.close();                        key.cancel()						remoteConnClosed = true;					}									}                //这里必须移除掉该selectionKey, 否则下次select调用时还会存在				iter.remove();			}		}	}	private static String createHttpMsg() {		StringBuffer sBuffer = new StringBuffer();		sBuffer.append("GET / HTTP/1.1").append("\r\n");		sBuffer.append("Host: chushu.la").append("\r\n");//		sBuffer.append("Connection: Closed");		sBuffer.append("Connection: keep-alive");		sBuffer.append("\r\n").append("\r\n");		return sBuffer.toString();	}		public static void sendMessage(SocketChannel client, String msg)throws Exception {		ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());        client.write(buffer);    }}