创建ObjectOutputStream和ObjectInputStream对象顺序

[wd9053]

在试着写一个聊天程序。
客户端连接到服务器后，发送一个Order类的对象，其中包含一个字符串，然后在服务器的标准输出中打印出该字符串。
运行时发现在创建ObjectOutputStream对象和ObjectInputStream对象时，如果先创建ObjectOutputStream对象则程序正常进行，反之若先创建ObjectInputStream对象则程序会卡在创建ObjectInputStream对象时。请高手指教。
下面是截取的一部分代码

Order.java

import java.io.Serializable;

public class Order implements Serializable
{
  private static final long serialVersionUID = 1234567890123L;
  private String context;
  public Order(String context)
  {
    this.context = context;
  }
  
  public String getContext()
  {
    return context;
  }
}

Server.java

import java.io.InputStream;
import java.io.OutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class Server
{
    private    InputStream    is;
    private    ObjectInputStream    ois;
    private    ObjectOutputStream oos;
    private    OutputStream os;
    
    public Server()
    {
        try
        {
            ServerSocket server    =    new    ServerSocket(6000);
            Socket client    =    server.accept();
            is = client.getInputStream();
            os = client.getOutputStream();
            
            /*
            oos    =    new    ObjectOutputStream(os);
            ois    =    new    ObjectInputStream(is);
            */
            
            ois    =    new    ObjectInputStream(is);////////////////////////////这两行若交换位置，则程序会正常运行
            oos    =    new    ObjectOutputStream(os);////////////////////////////

            Order    order    =    (Order)ois.readObject();
            System.out.println(order.getContext());
        }
        catch    (Exception e)
        {
            e.printStackTrace();
        }
    }
    
    public static    void main(String[] args)
    {
        new    Server();
    }
}

Client.java

import java.io.InputStream;
import java.io.OutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.Socket;
import java.net.InetAddress;

public class Client
{
    private    InputStream    is;
    private    ObjectInputStream    ois;
    private    ObjectOutputStream oos;
    private    OutputStream os;
    
    public Client()
    {
        try
        {
            Socket client    =    new    Socket(InetAddress.getByName("localhost"), 6000);
            is = client.getInputStream();
            os = client.getOutputStream();
            ois    =    new    ObjectInputStream(is);
            oos    =    new    ObjectOutputStream(os);
            
            oos.writeObject(new    Order("asfd"));
        }
        catch    (Exception e)
        {
            e.printStackTrace();
        }
    }
    
    public static    void main(String[] args)
    {
        new    Client();
    }
}

[swandragon]

public ObjectInputStream(InputStream in)
throws IOException创建从指定 InputStream 读取的 ObjectInputStream。从流读取序列化头部并予以验证。在对应的 ObjectOutputStream 写入并刷新头部之前，此构造方法将阻塞