紧急求助：请问如何解决JAVA socket通信时的缓冲区的问题

Question

我用servlet作的socket连接客户端的访问程序；需要用web页面通过socket收发远程客户端的数据信息；每次连接客户端是通过数据库查询ip及port后，用相应的ip及port进行连接；为什么连上以后向客户端发送信息后再读取客户端返回过来的信息都是一样的？servlet不是多线程的吗？每连接一个socket应该都是新的线程；为什么输入缓冲区里的数据还是一直是以前同一个客户端返回的数据；连接新的连接后读取缓冲区的数据还是旧的？是不是每个连接的缓冲区都是是共享的吗？请问能不能为每个socket连接建立独立的缓冲区？谢谢！下面是我的一部分代码请大家指教：servlet的
 public void doGet(HttpServletRequest request, HttpServletResponse response) throws
            ServletException, IOException {
        response.setContentType(CONTENT_TYPE);
        PrintWriter out = response.getWriter();
        sta=(StationVO) request.getAttribute("setst");\\得到数据库查询数据
        out.println("<input type=hidden name=id value=\""+sta.getId()+"\"/>");
        out.println("<input type=hidden name=type value=\""+request.getParameter("type")+"\"/>");
        String host=sta.getSIp();\\从bean得到查询的ip
        int port=sta.getSPort();\\从bean得到查询的port
        if(socketbean.cSocket==null){
             socketbean.connectionsocket(host,port);\\通过socketbean连接
         }
        else if(socketbean.cSocket!=null){
             try {
                 socketbean.searchtw();
                 if (socketbean.getDataInputStream() != null) {
                     socketbean.read();\\每次读的还是以前的数据，如何解决？
                 }
             } catch (Exception e) {          }      socketbean的代码：import java.net.*;
import java.io.*;
import java.util.*;
import java.lang.*;public class SocketBean {    public SocketBean() {
    }
    private String Address; //服务器地址
    private int Port; //服务器端口
    public Socket cSocket = null; //Socket
    public byte[] a = new byte[16];
    private DataOutputStream dos = null;
    private DataInputStream dis = null;
    boolean bconnect = false;
    private static SocketBean me=new SocketBean();
    public static SocketBean newInstance() {
       return me;
    }    public void setDataOutputStream(DataOutputStream Dos){
        dos=Dos;
    }
    public DataOutputStream getDataOutputStream(){
        return dos;
    }
    public void setDataInputStream(DataInputStream Dis){
        dis=Dis;
    }
    public DataInputStream getDataInputStream(){
        return dis;
    }    public void setAddress(String address) { //设置服务器地址
        Address = address;
    }    public void setPort(int port) { //设置服务器端口
        Port = port;
    }    public String getAddress() { //获取服务器地址
        return Address;
    }    public int getPort() { //获取服务器端口
        return Port;
    }
    public  void connectionsocket(String HostName,int Port){       try {
           this.Address=HostName;
           this.Port=Port;
           SocketAddress addr = new InetSocketAddress(Address, Port);
           //生成一个socket
           cSocket=new Socket(Address,Port);
           cSocket.setKeepAlive(true);
           dos = new DataOutputStream(cSocket.getOutputStream());
           dis = new DataInputStream(cSocket.getInputStream());
           bconnect = true;
           while (!cSocket.isConnected()) {
               System.out.println("connection has  not been established!...");
           }
           System.out.println("connection has been established!...");
       } catch (IOException e) {
           System.out.println(e);
       }
   }    public void Close() {
        try {
            if (cSocket != null) {
                cSocket.close();
            }
        } catch (IOException e) {
            System.out.println(e);
        } finally {
            try {
                dos.close();
                dis.close();
                cSocket.close();
            } catch (IOException ex) {
            }
        }
    }    public void searchtw() {
            int[] b = new int[8];
            b[0] = 0xf8;
            b[1] = 0xf9;
            b[2] = 0x0f;
            b[3] = 0xff;
            b[4] = 0x24;
            b[5] = 0x00;
            b[6] = 0xfe;
            b[7] = 0xff;
            try {
                    dos.write(b[0]);
                    dos.write(b[1]);
                    dos.write(b[2]);
                    dos.write(b[3]);
                    dos.write(b[4]);
                    dos.write(b[5]);
                    dos.write(b[6]);
                    dos.write(b[7]);
                    dos.flush();
            }
            catch (IOException e) {
                e.printStackTrace();
            }
    }    public void read() {
        try {
                if(dis!=null){dis.readFully(a);
                    System.out.println(a[5]);
                    System.out.println(a[6]);
                    System.out.println(a[7]);
                    System.out.println(a[8]);
                    System.out.println(a[9]);
                    System.out.println(a[10]);
                    System.out.println(a[11]);
                    System.out.println(a[12]);
                }
                System.out.println("");        } catch (Exception ex) {
        }
    }
}