套接字中的 Java 客户端

Question

我一直在寻找一种方法来使用 java 连接到在 Python 中创建的服务器。

谁能告诉我如何连接 java 以及如何发送字符串？ 建议它也适用于 Android

我在 python 中的服务器：

import socket, time

soc = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
soc.bind(("160.07.08.49", 6784))

soc.listen(5)
(client, (ipNum, portNum)) = soc.accept()

while True:
    print(client.recv(1024))
    time.sleep(0.5)

我在 Java 的客户：

        try {
            Socket socket = new Socket("160.07.08.49", 6784);

            PrintWriter printWriter = new PrintWriter(socket.getOutputStream());
            printWriter.write("Hello from java");
            printWriter.flush();
            printWriter.close();
        }catch (Exception e) {e.printStackTrace();}

当 Java 客户端连接时，我从 python 收到错误

    print(soc.recv(20))
A request to send or receive data was disallowed because the socket is not connected and (when sending on a datagram socket using a sendto call) no address was supplied

Answer 1

Python 回显服务器：

import socket

HOST = 'localhost'
PORT = 6784

while True:
    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
        s.bind((HOST, PORT))
        s.listen()
        conn, addr = s.accept()
        with conn:
            print('Connected by', addr)
            while True:
                data = conn.recv(1024)
                if not data:
                    break
                conn.sendall(data)

Java客户端：

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

public class JavaClient {

   public static void main(String [] args) {
      String serverName = "localhost";
      int port = 6784;

      try {
         Socket client = new Socket(serverName, port);
         
         OutputStream outToServer = client.getOutputStream();
         DataOutputStream out = new DataOutputStream(outToServer);
         
         out.writeUTF("Hello from " + client.getLocalSocketAddress());
         InputStream inFromServer = client.getInputStream();
         DataInputStream in = new DataInputStream(inFromServer);
         
         System.out.println("Server says " + in.readUTF());
         client.close();
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}

最大的区别是我正在做localhost到localhost 。 如果您需要从 localhost 外部获得 Python 服务器，请将bind行更改为：

soc.bind(("0.0.0.0", 6784))

这样服务器就会监听所有可用的接口。 然后让您的 Java 客户端连接到服务器的外部 IP。