Java - 使用 ObjectStream 发送套接字

Question

我有一个套接字，我想从客户端发送到服务器（或反向）。

当 java.net.Socket 属于 java.lang.Object 时，为什么不能使用 ObjectStream 完成？我怎样才能正确地做到这一点？

这是Server.java：

package com.company;

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;

public class Server {
    public static void main(String[] args) throws IOException, ClassNotFoundException {
        ServerSocket ss = new ServerSocket(1234);       // make server on localhost:1234
        Socket socket = ss.accept();

        System.out.println("Connection from " + socket + "!\n");

        InputStream inputStream = socket.getInputStream();
        ObjectInputStream objectInputStream = new ObjectInputStream(inputStream);

        Socket receivedSocket = (Socket) objectInputStream.readObject();
        System.out.println(receivedSocket);

        ss.close();
        socket.close();
    }
}

这是Client.java：

package com.company;

import java.io.*;
import java.net.Socket;

public class Client {

    public static void main(String[] args) throws IOException {
        Socket socket = new Socket("localhost", 1234); // make socket on localhost:1234

        OutputStream outputStream = socket.getOutputStream();
        ObjectOutputStream objectOutputStream = new ObjectOutputStream(outputStream);

        objectOutputStream.writeObject(socket);     // send `socket` over network

        socket.close();
    }
}

在Client 方面，它向我抛出了这个异常：

Exception in thread "main" java.io.NotSerializableException: java.net.Socket
    at java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1192)
    at java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:352)
    at com.company.Client.main(Client.java:14)

这在Server 方面：

Exception in thread "main" java.io.WriteAbortedException: writing aborted; java.io.NotSerializableException: java.net.Socket
    at java.base/java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1696)
    at java.base/java.io.ObjectInputStream.readObject(ObjectInputStream.java:495)
    at java.base/java.io.ObjectInputStream.readObject(ObjectInputStream.java:453)
    at com.company.Server.main(Server.java:17)
Caused by: java.io.NotSerializableException: java.net.Socket
    at java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1192)
    at java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:352)
    at com.company.Client.main(Client.java:14)

提前致谢！

Answer 1

您只能编写实现java.io.Serializable 接口的对象。您可以创建一个包含来自 Socket 的信息的配置类：

public class SocketConfiguration implements Serializable {
    
    private final String host;
    private final int port;

    public SocketConfiguration(String host, int port) {
        this.host = host;
        this.port = port;
    }

    public String getHost() {
        return host;
    }

    public int getPort() {
        return port;
    }
}

尽管上面的示例毫无意义，因为您已经知道所有这些信息。您还可以创建一个扩展 java.net.Socket 并实现 java.io.Serializable 的类，但我真的不明白这样做的意义。