我可以只使用套接字在 Java 和 C# 之间进行通信吗? [英] Can I communicate between Java and C# using just sockets?

问题描述

更具体地说，如果计算机有服务器(java.net.ServerSocket 实例)，我可以使用 C# System.Net.Sockets.Socket 连接到它实例?

More specifically, if a computer has a server (a java.net.ServerSocket instance) can I connect to it using a C# System.Net.Sockets.Socket instance?

推荐答案

主要问题是您需要非常小心地对发送和接收的数据进行编码.这是一对可以协同工作的程序.C# 客户端发送一个字符串，首先将其长度作为整数发送，然后发送字符串本身的字节.Java 服务器读取长度，然后读取消息并将输出打印到控制台.然后编写回声消息，计算其长度，提取字节并将其发送回 C# 客户端.客户端读取长度、消息并打印输出.应该有一种方法可以避免所有按位计算的东西，但老实说，我对这些东西有点生疏，尤其是在 Java 方面.

The main issue is that you need to be very careful with the encoding of the data that you send and receive. Here is a pair of programs that work together. The C# client sends a string, by first sending its length as an integer, and then sending the bytes of the string itself. The Java server reads the length, then reads the message and prints an output to the console. Then composes an echo message, computes its length, extracts the bytes and sends it back to the C# client. The client reads the length, the message and prints an output. There should be a way to avoid all the bitwise stuff, but honestly I'm a little rusty with this stuff, especially on the Java side.

Java 服务器:

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class JavaSocket {

    public static void main(String[] args) throws IOException {

        ServerSocket serverSocket = new ServerSocket(4343, 10);
        Socket socket = serverSocket.accept();
        InputStream is = socket.getInputStream();
        OutputStream os = socket.getOutputStream();

        // Receiving
        byte[] lenBytes = new byte[4];
        is.read(lenBytes, 0, 4);
        int len = (((lenBytes[3] & 0xff) << 24) | ((lenBytes[2] & 0xff) << 16) |
                  ((lenBytes[1] & 0xff) << 8) | (lenBytes[0] & 0xff));
        byte[] receivedBytes = new byte[len];
        is.read(receivedBytes, 0, len);
        String received = new String(receivedBytes, 0, len);

        System.out.println("Server received: " + received);

        // Sending
        String toSend = "Echo: " + received;
        byte[] toSendBytes = toSend.getBytes();
        int toSendLen = toSendBytes.length;
        byte[] toSendLenBytes = new byte[4];
        toSendLenBytes[0] = (byte)(toSendLen & 0xff);
        toSendLenBytes[1] = (byte)((toSendLen >> 8) & 0xff);
        toSendLenBytes[2] = (byte)((toSendLen >> 16) & 0xff);
        toSendLenBytes[3] = (byte)((toSendLen >> 24) & 0xff);
        os.write(toSendLenBytes);
        os.write(toSendBytes);

        socket.close();
        serverSocket.close();
    }
}

一个 C# 客户端:

using System;
using System.Net;
using System.Net.Sockets;

namespace CSharpSocket
{
    class MainClass
    {
        public static void Main (string[] args)
        {
            string toSend = "Hello!";

            IPEndPoint serverAddress = new IPEndPoint(IPAddress.Parse("192.168.0.6"), 4343);

            Socket clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            clientSocket.Connect(serverAddress);

            // Sending
            int toSendLen = System.Text.Encoding.ASCII.GetByteCount(toSend);
            byte[] toSendBytes = System.Text.Encoding.ASCII.GetBytes(toSend);
            byte[] toSendLenBytes = System.BitConverter.GetBytes(toSendLen);
            clientSocket.Send(toSendLenBytes);
            clientSocket.Send(toSendBytes);

            // Receiving
            byte[] rcvLenBytes = new byte[4];
            clientSocket.Receive(rcvLenBytes);
            int rcvLen = System.BitConverter.ToInt32(rcvLenBytes, 0);
            byte[] rcvBytes = new byte[rcvLen];
            clientSocket.Receive(rcvBytes);
            String rcv = System.Text.Encoding.ASCII.GetString(rcvBytes);

            Console.WriteLine("Client received: " + rcv);

            clientSocket.Close();
        }
    }
}

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