高分求救：如何用 ServerSocketChannel & SocketChannel做的一个接收客户端的数据包？（在线）

1、客户端程序可以连上来，但发送一次之后，发送第2次，服务器就出问题了，主要是在run()方法中的while   (selector.select()   >   0)这句上，本来selector.select()应该是阻塞的，但第2次发送后，就不阻塞了，立刻返回，而且为false。请问这是为什么？


2、连第二个客户端的时候，程序也没有检测到，key.isAcceptable()始终为false，是怎么回事？

代码如下：
public   void   init(int   portNumber)   throws   Exception{
//分配一个ServerSockerChannel
serverChannel   =   ServerSocketChannel.open();
//从ServerSocketChannel里获得一个对应的Socket
serverSocket   =   serverChannel.socket();
//生成一个Selector
selector   =   Selector.open();
//把socket绑定到端口上
serverSocket.bind(new   InetSocketAddress(portNumber));
//serverChannel为非bolck
serverChannel.configureBlocking(false);
//通过Selector注册ServerSocketChannel
//serverChannel.register(selector,SelectionKey.OP_ACCEPT);
serverChannel.register(selector,SelectionKey.OP_ACCEPT);
}

protected   void   registerChannel(Selector   selector,SelectableChannel   channel,int   ops)   throws   Exception{
if   (channel   ==   null){
return;
}
channel.configureBlocking(false);
channel.register(selector,ops);
}

protected   void   processData(SelectionKey   key)   throws   Exception{
SocketChannel   socketChannel   =   (SocketChannel)key.channel();
USSDMessage   message   =   (USSDMessage)messageFactory.createMessage( " ")   ;
USSDEvent   event   =   null;
int   count;
buffer.clear();
//读取所有的数据
while((count   =   socketChannel.read(buffer))   > 0){
System.out.println( "count: "+count);
buffer.flip();
while(buffer.hasRemaining()){
message.buildMessageFromBuffer(buffer);
if(message   !=   null){
int   intCmdId   =   message.getCmdId();
        if(intCmdId   ==   Constant.USSD_MESSAGE_COMMAND_SURVEILLANCE_REQ)
        {  
        event   =   new   USSDEvent(buffer);
                                this.applicationContext.publishEvent(event);
  }
        message   =   this.resetUSSDMessage(message);        
        buffer.clear();
ByteBuffer   newBuffer   =   buffer.slice()   ;
  message.appendToBuffer(newBuffer);
  System.out.println( "buffer   write   to   socketChannel   begin! ");
//   message.buildMessageFromBuffer(buffer);
  socketChannel.write(buffer);     //在socket里写数据
  System.out.println( "buffer   write   to   socketChannel   end! ");
  }
}
buffer.clear();     //清空buffer
// count   =   -1;
// break;
}
if(count   <   0){
//count <0，说明已经读取完毕
socketChannel.close();
}

}
private   void   processData(SocketChannel   socketChannel)   throws   Exception
{
USSDMessage   message   =   (USSDMessage)messageFactory.createMessage( " ")   ;
USSDEvent   event   =