在 Java 套接字中使用 ObjectInputStream 不读取任何内容

Question

I created a simple server and a client, but the server could not read anything that was sent from the client. I also add a print statement after I sent the string, but it cannot be printed either.

public class Server {
                public static void main(String[] args) throws IOException, ClassNotFoundException {
                    ServerSocket serverSocket = new ServerSocket(6666);

                    Socket clientSocket = serverSocket.accept();
                    System.out.println("accepting client at address " + clientSocket.getRemoteSocketAddress());
                    ObjectInputStream in = new ObjectInputStream(clientSocket.getInputStream());
                    ObjectOutputStream out = new ObjectOutputStream(clientSocket.getOutputStream());

                    String input = (String) in.readObject();
                    System.out.println(input);
                    out.writeObject("Received");
                    out.flush();
                }
}

Below is the client, and I just want to send a string "?????does not send":

 public class Test {

        public static void main(String[] args) throws IOException, ClassNotFoundException {
            Client client = new Client();
            client.sentInfo();
        }

        private static class Client {

            private ObjectInputStream objectInputStream;
            private ObjectOutputStream objectOutputStream;

            public Client() throws IOException {
                Socket socket = new Socket("127.0.0.1", 6666);
                this.objectInputStream = new ObjectInputStream(socket.getInputStream());
                this.objectOutputStream = new ObjectOutputStream(socket.getOutputStream());
            }

            public void sentInfo() throws IOException, ClassNotFoundException {
                this.objectOutputStream.writeObject("?????does not send");
                this.objectOutputStream.flush();
                System.out.println("????????");
                Message resp = (Message) this.objectInputStream.readObject();
                System.out.println(resp.getMessage());
            }

        }
 }

---

I tried something else, if I just use InputStream and use a buffer to read bytes, like this: Server code

This is the client code: client code

The code in the two link above would work. However, it would not work if I tried to use ObjectInputStream:

This is the server: server

This is the client: client

This is the Message object I want to send: Message class

Can someone explain this for me please? Thanks!

Answer 1

To read Strings from a socket use something like this:

DataInputStream input = new DataInputStream(clientSocket.getInputStream()); String message = input.readUTF();

You can open multiple streams from a socket, so if you want to read something else that really needs the ObjectInputStream than it can be open as well. Don't forget to properly close the streams & sockets.