java基于NIO实现群聊模式

package com.qst.chat;

import java.io.IOException;
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.Scanner;

public class GroupChatClient {
 private final int PORT = 9999;
 private final String HOST = "localhost";
 private SocketChannel channel;
 private static Selector selector;

 private String name;
 
 public GroupChatClient() throws IOException {

  selector = Selector.open();
  // 连接服务器
  channel = SocketChannel.open(new InetSocketAddress(HOST, PORT));
  // 设置非阻塞
  channel.configureBlocking(false);
  // 将channel 注册到selector
  channel.register(selector, SelectionKey.OP_READ);
   name = channel.getLocalAddress().toString().substring(1);

  System.out.println(name + "is ok ....");

 }
 // 向服务器发送消息
 public void sendTO(String msg) {
  
  ByteBuffer buffer = ByteBuffer.wrap((name+":"+msg).getBytes());
  try {
   channel.write(buffer);
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }

 }
 // 读取从服务器端回复的消息
 public static void getInfo() {
  
  try {
   if(selector.select() >0) {
    Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
    
    while(iterator.hasNext()) {
     SelectionKey key = iterator.next();
     
     if(key.isReadable()) {
     // 得到通道
     SocketChannel sc =  (SocketChannel) key.channel();
     
     ByteBuffer buffer = ByteBuffer.allocate(1024);
     
     int len;
     
     // 把读到的缓冲区的数据转成字符串
     while((len = sc.read(buffer)) > 0) {
      System.out.println(new String(buffer.array()));
     }
     
     }
  
     
    }
    // 删除当前的selectionKey, 防止重复操作
    iterator.remove();
    
   }
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  
 }
 
 public static void main(String[] args) {
  try {
   GroupChatClient client = new GroupChatClient();
   
   
   new Thread() {
    
    
    public void run() {
     while(true)
     {
      try {
       Thread.sleep(3000);
       GroupChatClient.getInfo();
      } catch (InterruptedException e) {
       // TODO Auto-generated catch block
       e.printStackTrace();
      }
     }
     
    };
   }.start();
   
   
   Scanner sc = new Scanner(System.in);
//   while(true) {
//    String name = sc.nextLine();
//    client.sendTO(name);
//   }
   while(sc.hasNextLine()) {
      String s = sc.nextLine();
              client.sendTO(s);
   }
   
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
 }

}

package com.qst.chat;

import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.ByteBuffer;
import java.nio.channels.SelectableChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.time.chrono.IsoChronology;
import java.util.Iterator;

import com.sun.accessibility.internal.resources.accessibility;

import sun.print.resources.serviceui;

public class GroupChatServer {

 private static ServerSocketChannel socketChannel;
 private static Socket socket;
 private static Selector selector;
 private static SocketChannel accept;

 public GroupChatServer() throws IOException {

  socketChannel = ServerSocketChannel.open();

  selector = Selector.open();
  // 绑定端口
  socketChannel.socket().bind(new InetSocketAddress(9999));
  // 设置非阻塞模式
  socketChannel.configureBlocking(false);

  // 将该通道 注册到selector
  socketChannel.register(selector, SelectionKey.OP_ACCEPT);

 }

 // 监听
 public static void listen() {
  System.out.println("监听线程: " + Thread.currentThread().getName());
  try {
   while (selector.select() > 0) {

    Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();

    if (iterator.hasNext()) {
     // 遍历得到selectionKey 集合
     SelectionKey next = iterator.next();
     if (next.isAcceptable()) {
      next.channel();
      // socketChannel = (ServerSocketChannel) next.channel();
      SocketChannel accept = socketChannel.accept();
      accept.configureBlocking(false);

      accept.register(selector, SelectionKey.OP_READ);

       System.out.println(accept.getRemoteAddress()+" 上线 了。。。");
     }
     if (next.isReadable()) {
      readDate(next);

     }

     // 移除当前的next，防止重复处理
     iterator.remove();
     // System.out.println("未发现");

    }

   }
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }

 }

 // 读取客户端消息
 public static void readDate(SelectionKey key) {

  try {
   accept = (SocketChannel) key.channel();
   ByteBuffer buffer = ByteBuffer.allocate(1024);
   int len = accept.read(buffer);
   if (len > 0) {
    buffer.flip();
    String msg = new String(buffer.array());
    System.out.println("user = " + msg);

    // 向其它的客户端转发消息(去掉自己)
    sendToAll(msg, accept);
    buffer.clear();
   }
  } catch (IOException e) {
   // TODO Auto-generated catch block
   try {
    String msg = accept.getRemoteAddress().toString();
    // 取消注册
    key.cancel();
    // 关闭通道
    accept.close();
    System.out.println(msg + "离线了");
   } catch (IOException e1) {
    // TODO Auto-generated catch block
    e1.printStackTrace();
   }
   // e.printStackTrace();
  } finally {
   // TODO: handle finally clause
  }
 }

 public static void sendToAll(String msg, SocketChannel ssc) {
  for (SelectionKey ss : selector.keys()) {
   // 通过 key 取出对应的 SocketChannel
   SelectableChannel channel = ss.channel();

   // 排除自己
   if (channel instanceof SocketChannel && channel != ssc) {
    // 转型
    SocketChannel sh = (SocketChannel) channel;
    // 转存到buffer
    ByteBuffer wrap = ByteBuffer.wrap(msg.getBytes());
    try {
     // 写入通道
     sh.write(wrap);
    } catch (IOException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }
   }
  }
 }

 public static void main(String[] args) throws IOException {
  GroupChatServer server = new GroupChatServer();
  GroupChatServer.listen();

 }

}