分2个程序，服务器和客户，为了方便输入，每个程序都专门建立了一个线程进行写，而主线程负责读
编译没错，运行的效果却不对，请指点：
这个是服务器的：

import import import import import import public class ServerTest {

    public static void main(String[] args) {
        new ServerTest(PORT).gogo();
    }
   

    private static final int PORT = 400;
    private ServerSocket server;
    private Socket socket;
    private PrintWriter writer;
    private BufferedReader reader;
    private BufferedReader in;  //用户写
    private Runnable writeThread;
    private String humanStr;
    private String clientStr;
   

    public ServerTest(int port){
        try{
            server = new ServerSocket(port);
            System.out.println("Server 已经建立...");
        }
        catch(Exception e1){
            e1.printStackTrace();
        }
    }
   

    public void gogo(){
        try{
            System.out.println("in gogo()...");
            socket = server.accept();
            System.out.println("Client 已经连接...");
            in = new BufferedReader(new InputStreamReader(System.in));
            writer = new PrintWriter(socket.getOutputStream());
            reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
           

            writeThread = new Runnable(){
                            public void run(){
                                try {
                                    while((humanStr = in.readLine()) != null){
                                        System.out.println("Server: " + humanStr);
                                        writer.write(humanStr + "\n");
                                    }
                                } catch (IOException e2) {
                                    e2.printStackTrace();
                                }
                            }
                        };
            new Thread(writeThread).start();
           

            //System.out.println("before read");
            while((clientStr = reader.readLine()) != null){
                System.out.println("Client: " + clientStr + "\n");
            }
            //System.out.println("after read");
           

            in.close();
            writer.close();
            reader.close();
            socket.close();
            server.close();
        }
        catch(Exception e3){
            e3.printStackTrace();
        }
    }
   

}

这个是客户端的：

import import import import import import public class ClientTest {

    public static void main(String[] args) {
        new ClientTest(PORT).gogo();
    }
   

    private static final int PORT = 400;
    private Socket socket;
    private InetAddress address;
    private PrintWriter writer;
    private BufferedReader reader;
    private BufferedReader in;  //用户写
    private Runnable writeThread;
    private String humanStr;
    private String serverStr;
   

    public ClientTest(int port){
        try{
            address = InetAddress.getLocalHost();
            socket = new Socket(address,port);
        }
        catch(Exception e1){
            e1.printStackTrace();
        }
    }
   

    public void gogo(){
        try{
            in = new BufferedReader(new InputStreamReader(System.in));
            reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            writer = new PrintWriter(socket.getOutputStream());
           

            writeThread = new Runnable(){
                public void run(){
                    try {
                        while((humanStr = in.readLine()) != null){
                            System.out.println("Client: " + humanStr + "\n");
                            writer.write(humanStr + "\n");
                        }
                    } catch (IOException e2) {
                        e2.printStackTrace();
                    }
                }
            };
            new Thread(writeThread).start();
           

            //System.out.println("before read");
            while ((serverStr = reader.readLine()) != null){
                System.out.println("Server: " + serverStr + "\n");
            }
            //System.out.println("after read");
           

            in.close();
            reader.close();
            writer.close();
            socket.close();
        }
        catch(Exception e3){
            e3.printStackTrace();
        }
    }
}

求指教哇！！！谢谢。