package thread2;
import java.io.*;
import java.nio.*;
import java.nio.channels.*;
import java.nio.charset.*;
import java.net.*;
import java.util.*;

public class EchoServer{
  private Selector selector = null;
  private ServerSocketChannel serverSocketChannel = null;
  private int port = 8000;
  private Charset charset=Charset.forName("GBK");

  public EchoServer()throws IOException{
    selector = Selector.open();
    serverSocketChannel= ServerSocketChannel.open();
    serverSocketChannel.socket().setReuseAddress(true);
    serverSocketChannel.socket().bind(new InetSocketAddress(port));
    System.out.println("服務器啟動");
  }

  public void accept(){
      for(;;){
        try{
            SocketChannel socketChannel = serverSocketChannel.accept();
            System.out.println("接收到客戶連接，來自:" +
                               socketChannel.socket().getInetAddress() +
                               ":" + socketChannel.socket().getPort());
            socketChannel.configureBlocking(false);

            ByteBuffer buffer = ByteBuffer.allocate(1024);
            synchronized(gate){
                selector.wakeup();
                socketChannel.register(selector,
                                       SelectionKey.OP_READ |
                                       SelectionKey.OP_WRITE, buffer);
            }
        }catch(IOException e){e.printStackTrace();}
      }
  }
  private Object gate=new Object();
  public void service() throws IOException{
    for(;;){
      synchronized(gate){}
      int n = selector.select();

      if(n==0)continue;
      Set readyKeys = selector.selectedKeys();
      Iterator it = readyKeys.iterator();
      while (it.hasNext()){
        SelectionKey key=null;
        try{
            key = (SelectionKey) it.next();
            it.remove();
            if (key.isReadable()) {
                receive(key);
            }
            if (key.isWritable()) {
                send(key);
            }
        }catch(IOException e){
           e.printStackTrace();
           try{
               if(key!=null){
                   key.cancel();
                   key.channel().close();
               }
           }catch(Exception ex){e.printStackTrace();}
        }
      }//#while
    }//#while
  }

  public void send(SelectionKey key)throws IOException{
    ByteBuffer buffer=(ByteBuffer)key.attachment();
    SocketChannel socketChannel=(SocketChannel)key.channel();
    buffer.flip();  //把極限設為位置
    String data=decode(buffer);
    if(data.indexOf("\n")==-1)return;
    String outputData=data.substring(0,data.indexOf("\n")+1);
    System.out.print(outputData);
    ByteBuffer outputBuffer=encode("echo:"+outputData);
    while(outputBuffer.hasRemaining())
      socketChannel.write(outputBuffer);

    ByteBuffer temp=encode(outputData);
    buffer.position(temp.limit());
    buffer.compact();

    if(outputData.equals("bye\r\n")){
      key.cancel();
      socketChannel.close();
      System.out.println("關閉與客戶的連接");
    }
  }

  public void receive(SelectionKey key)throws IOException{
    ByteBuffer buffer=(ByteBuffer)key.attachment();

    SocketChannel socketChannel=(SocketChannel)key.channel();
    ByteBuffer readBuff= ByteBuffer.allocate(32);
    socketChannel.read(readBuff);
    readBuff.flip();

    buffer.limit(buffer.capacity());
    buffer.put(readBuff);
  }

  public String decode(ByteBuffer buffer){  //解碼
    CharBuffer charBuffer= charset.decode(buffer);
    return charBuffer.toString();
  }
  public ByteBuffer encode(String str){  //編碼
    return charset.encode(str);
  }

  public static void main(String args[])throws Exception{
    final EchoServer server = new EchoServer();
    Thread accept=new Thread(){
        public void run(){
            server.accept();
        }
    };
    accept.start();
    server.service();
  }
}





/****************************************************
 * 作者：孫衛琴                                     *
 * 來源：<<Java網絡編程精解>>                       *
 * 技術支持網址：www.javathinker.org                *
 ***************************************************/