Question

我是java客户端服务器通信的新手，我遇到了从客户端向服务器端发送对象的问题。不知何故，我的程序在尝试传输对象时卡住了。可能的原因可能是ObjectOutputStream实现。

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class Handler implements ActionListener {
   Client client = new Client();
   List<String> parameterList = new ArrayList<String>();
   ClientParameter parameter;

   public void actionPerformed(ActionEvent event) {
      if(event.getSource()==buttonConnect) {
         parameterList.add(username);
         parameterList.add(password);
         parameter = new ClientParameter(parameterList);
         client.connectToServer(parameter);
}

Object ClientParameter

public class ClientParameter {
   List<String> parameterList;

   public ClientParameter(List<String> parameterList) {
      this.parameterList = parameterList;
   }

   public List<String> getParameterList() {
      return parameterList;
   }
   public void setParameterList(List<String> parameterList) {
      this.parameterList = parameterList;
   }
}

班级客户

public void connectToServer(ClientParameter parameter) {
   // Verbindung mit dem Server herstellen
   Socket server = null;
   try {
      server = new Socket("localhost", 3141);
      // programm hangs while reading this 2 lines..
      ObjectInputStream objectIn = new ObjectInputStream(server.getInputStream());
      ObjectOutputStream objectOut = new ObjectOutputStream(server.getOutputStream());

      objectOut.writeObject(parameter);
   } catch(UnknownHostException e) {
      e.printStackTrace();
   } catch(IOException e) {
      e.printStackTrace();
   } finally {
      if(server!=null) {
         try {
            server.close();
         } catch(IOException e) {
            System.out.println(e);
         }
      }
   }
}

服务器类

public class Server {
   private static void handleConnection(Socket client) throws IOException {
      ObjectInputStream objectIn = new ObjectInputStream(client.getInputStream());
      ObjectOutputStream objectOut = new ObjectOutputStream(client.getOutputStream());

      ClientParameter parameter;
      try {
         parameter = (ClientParameter) objectIn.readObject();
         System.out.println(parameter);
      } catch (ClassNotFoundException e) {
         e.printStackTrace();
      }
   }

   public static void main(String[] args) throws IOException {
      ServerSocket server = new ServerSocket(3141);
      while(true) {
         Socket client = null;
         try {
            client = server.accept();
            handleConnection(client);
         }
         catch(IOException e) {
            e.printStackTrace();
         }
         finally {
            if(client!=null) {
               try {
                  client.close();
               }
               catch(IOException e) {
                  System.out.println(e);
               }
            }
         }
      }
   }
}

谢谢！

Answer 1

服务器首先读取客户端发送的内容。客户端也从读取服务器发送的内容开始。所以这是一个僵局。

确实，as documented，ObjectInputStream的构造函数阻塞，直到它收到序列化流头：

从流中读取序列化流标头并进行验证。此构造函数将阻塞，直到相应的ObjectOutputStream已写入并刷新标头。

删除以下行，因为您无论如何都不对ObjectInputStream执行任何操作：

ObjectInputStream objectIn = new ObjectInputStream(server.getInputStream());

ObjectOutputStream - 客户端/服务器通信

1 个答案: