NIO编程

package com.yunta.Server;

import java.io.IOException;
import java.net.InetSocketAddress;
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.nio.charset.Charset;
import java.util.Iterator;

public class ServerPC {
   
private Selector selector;
private ServerSocketChannel server;
    private ByteBuffer buffer=ByteBuffer.allocate(1024);
    private Charset charset=Charset.forName("GBK");

public  ServerPC(){
try {
selector=Selector.open();
    server=ServerSocketChannel.open();
server.socket().bind(new InetSocketAddress("localhost", 4444));
server.configureBlocking(false);
server.register(selector, SelectionKey.OP_ACCEPT);//注册服务器套接字通道

} catch (IOException e) {
// TODO Auto-generated catch blocks
e.printStackTrace();
}
}
public void init(){
try {
while(true){
selector.select();
Iterator<SelectionKey> it = selector.selectedKeys().iterator();
while(it.hasNext()){
SelectionKey sk= it.next();
if(sk.isAcceptable()){//如果此通道是服务器套接字通道执行
System.out.println("test");
SocketChannel socket = server.accept();
     socket.configureBlocking(false);
     socket.register(selector, SelectionKey.OP_READ);
     sk.interestOps(SelectionKey.OP_ACCEPT);
    
}
try{
if(sk.isReadable()){//如果是套接字通道
String content="";
SocketChannel  channel = (SocketChannel) sk.channel();
while(channel.read(buffer)>0){
buffer.flip(); 
                         content+=charset.decode(buffer); 
                         System.out.println("==================读取的数据是："+content); 
                         sk.interestOps(SelectionKey.OP_READ|SelectionKey.OP_WRITE);

}
}}catch(Exception e){
sk.cancel();
if( sk.channel()!=null){
sk.channel().close();
}
}

if(sk.isWritable()&&sk.isValid()){
SocketChannel  channel = (SocketChannel) sk.channel();
String content="you success\n";
channel.write(charset.encode(content));
System.out.println("==============服务器回复的数据"+content);
sk.interestOps(SelectionKey.OP_READ);
}
}
it.remove();
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}public static void main(String[] args){ 
        new ServerPC().init();
    } 

}