JAVA非阻塞Socket服务程序

import java.nio.channels.*;
import java.nio.charset.*;
import java.nio.*;

import java.util.*;
import java.io.*;
import java.net.*;

public class NBlockingServer {
      int port = 8000;
      int BUFFERSIZE = 1024;
      Selector selector = null;
      ServerSocketChannel serverChannel = null;
      HashMap clientChannelMap = null; //用来存放每一个客户连接对应的套接字和通道

      public NBlockingServer(int port) {
        this.clientChannelMap = new HashMap();
        this.port = port;
      }
      //throws IOException
      public void initialize()      {
        //初始化，分别实例化一个选择器，一个服务器端可选择通道
        try {
          this.selector = Selector.open();
          this.serverChannel = ServerSocketChannel.open();
          this.serverChannel.configureBlocking(false);
          InetAddress localhost = InetAddress.getLocalHost();
          InetSocketAddress isa = new InetSocketAddress(localhost, this.port);
          this.serverChannel.socket().bind(isa); //将该套接字绑定到服务器某一可用端口
        }
        catch (IOException ex) {
        }
      }

      //结束时释放资源 throws IOException 
      public void finalize() {
        try {
          this.serverChannel.close();
          this.selector.close();
        }
        catch (IOException ex) {
        }
      }

      //监听端口，当通道准备好时进行相应操作 throws IOException, InterruptedException
      public void portListening()      {
        //服务器端通道注册OP_ACCEPT事件
        try {
          SelectionKey acceptKey = this.serverChannel.register(this.selector,
              SelectionKey.OP_ACCEPT);
          //当有(已注册的事件)发生时,select()返回值将大于0
          while (acceptKey.selector().select() > 0) {
            //System.out.println("event happened");
            //取得所有已经准备好的所有选择键
            Set readyKeys = this.selector.selectedKeys();
            //使用迭代器对选择键进行轮询
            Iterator i = readyKeys.iterator();
            while (i.hasNext()) {
              SelectionKey key = (SelectionKey) i.next();
              i.remove(); //删除当前将要处理的选择键
              if (key.isAcceptable()) { //如果是有客户端连接请求
                System.out.println("more client connect in!");
                ServerSocketChannel nextReady = (ServerSocketChannel) key.channel();

                SocketChannel sc = (SocketChannel) nextReady.accept();
                //获取客户端套接字
                //Socket s = nextReady.accept().socket();
                Socket s = sc.socket();
                //SocketChannel s = nextReady.accept();
                //设置对应的通道为异步方式并注册感兴趣事件
                //SocketChannel schannel=(SocketChannel)s.getChannel();
                s.getChannel().configureBlocking(false);
                //SelectionKey readWriteKey =s.getChannel().register(this.selector,SelectionKey.OP_READ |SelectionKey.OP_WRITE);
                SelectionKey readWriteKey = s.getChannel().register(this.selector,
                    SelectionKey.OP_READ);
                //将注册的事件与该套接字联系起来
                readWriteKey.attach(s); //将给定的对象附加到此键。
                //将当前建立连接的客户端套接字及对应的通道存放在哈希表//clientChannelMap中
                this.clientChannelMap.put(s, new ClientChInstance(s.getChannel()));
              }
              else if (key.isReadable()) { //如果是通道读准备好事件
                System.out.println("Readable");
                //取得选择键对应的通道和套接字
                SelectableChannel nextReady = (SelectableChannel) key.channel();
                Socket socket = (Socket) key.attachment(); //// 检索当前的附加对象。
                //处理该事件，处理方法已封装在类ClientChInstance中
                this.readFromChannel(socket.getChannel(),
                                     (ClientChInstance)this.
                                     clientChannelMap.get(socket));
              }
              else if (key.isWritable()) { //如果是通道写准备好事件
                System.out.println("writeable");
                //取得套接字后处理，方法同上
                Socket socket = (Socket) key.attachment(); // 检索当前的附加对象。
                SocketChannel channel = (SocketChannel) socket.getChannel();
                this.writeToChannel(channel, "This is from server!");
              }
            }
          }
        }
        catch (ClosedChannelException ex) {
        }
        catch (IOException ex) {
        }
      }

      //对通道的写操作
      public void writeToChannel(SocketChannel channel, String message) {
        try {
          ByteBuffer buf = ByteBuffer.wrap(message.getBytes("gb2312"));
          int nbytes = channel.write(buf);
        }
        catch (IOException ex) {
          System.out.println("系统向客户端发送数据出错;");
        }
      }

      //将读入字节缓冲的信息解码
       public String decode(ByteBuffer byteBuffer) throws
           CharacterCodingException {
         Charset charset = Charset.forName("gb2312");
         CharsetDecoder decoder = charset.newDecoder();      //为此 charset 构造新的解码器。
         CharBuffer charBuffer = decoder.decode(byteBuffer);      // 把单个输入字节缓冲区的剩余内容解码到新分配的字符缓冲区的便捷方法。
         String result = charBuffer.toString();       //
         return result;
       }

   
      //对通道的读操作throws IOException, InterruptedException
      public void readFromChannel(SocketChannel channel,ClientChInstance clientInstance) {
        try {
          ByteBuffer byteBuffer = ByteBuffer.allocate(BUFFERSIZE);
          int nbytes = channel.read(byteBuffer);      //断开是出错
          //System.out.println(nbytes);
          byteBuffer.flip();
          String result = this.decode(byteBuffer);
          //当客户端发出”@exit”退出命令时，关闭其通道
          if (result.indexOf("@exit") >= 0) {
            channel.close();
            System.out.println("客户端关闭");
          }
          else {
            clientInstance.append(result.toString());
            //读入一行完毕，执行相应操作
            //if (result.indexOf("\n") >= 0) {
            System.out.println("client input" + result);
            clientInstance.execute();
            //}
          }
        }
        catch (IOException ex) {
          try {
            channel.close();
          }
          catch (IOException ex1) {
          }
        }
      }

      //该类封装了怎样对客户端的通道进行操作，具体实现可以通过重载execute()方法
      public class ClientChInstance {
        SocketChannel channel;
        MessageData mdata;      //业务处理模块
        StringBuffer buffer = new StringBuffer();
        public ClientChInstance(SocketChannel channel) {
          this.channel = channel;
          this.mdata= new MessageData();
        }

        public void execute()      {
          //String message = "AAA00100311111111000001100000200707161008220033         99999999hello,welcomd!this is      请求连接 first send.\n";
          String info=buffer.toString();
          String reinfo=mdata.isRigthData(info);
          System.out.println("系统向客户端发送信息:"+reinfo);
          if(reinfo!=null){
            writeToChannel(this.channel, reinfo);
          }
          buffer = new StringBuffer();
        }

        //当一行没有结束时，将当前字窜置于缓冲尾
        public void append(String values) {
          buffer.append(values);
          //mdata=new MessageData(this);
        }
      }

      //主程序
      public static void main(String[] args) {
        NBlockingServer nbServer = new NBlockingServer(8000);
        try {
          nbServer.initialize();
        }
        catch (Exception e) {
          e.printStackTrace();
          System.exit( -1);
        }
        try {
          nbServer.portListening();
        }
        catch (Exception e) {
          e.printStackTrace();
        }
      }
}