java - 使用java通过套接字接收python json

Question

我一直在学习通过套接字将 Java 代码连接到 Python 的多个教程。

使用 json 数组从 java 发送到 python 效果很好。但是，我似乎无法用java接收东西。我真的不明白听力应该如何进行。现在我只听 15 秒的 while 循环(python 应该在收到输入后立即发送)，但我觉得我做错了很多事。也许有人有想法？

客户端.py:

import socket
import sys
import numpy as np
import json

# Create a TCP/IP socket
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

# Bind the socket to the port
server_address = ('localhost', 10004)
print >>sys.stderr, 'starting up on %s port %s' % server_address
sock.bind(server_address)

# Listen for incoming connections
sock.listen(1)

def mysum(x):
    return np.sum(x)

while True:
    # Wait for a connection
    print >>sys.stderr, 'waiting for a connection'
    connection, client_address = sock.accept()
    infile = sock.makefile();

    try:
        print >>sys.stderr, 'connection from', client_address

        # Receive the data in small chunks and retransmit it
        data = b''
        while True:
             new_data = connection.recv(16)
             if new_data:
                 # connection.sendall(data)
                 data += new_data
             else:
                 data += new_data[:]
                 print >>sys.stderr, 'no more data from', client_address
                 break
        data= data.strip('\n');
        print("data well received!: ")
        print(data,)
        print(np.array(json.loads(data)));

        #send a new array back

        sendArray =  np.array( [ (1.5,2,3), (4,5,6) ] );
        print("Preparing to send this:");
        print(sendArray);
        connection.send(json.dumps(sendArray.tolist()));

    except Exception as e:
        print(e)
        connection.close()
        print("closed");
    finally:
        # Clean up the connection
        connection.close()
        print("closed");

服务器.java:

import java.io.*;
import java.net.Socket;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;

import org.json.*;

import java.net.ServerSocket;

public class SocketTest {

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


        String hostName = "localhost";
        int portNumber = 10004;

        try (

                //open a socket
                Socket clientSocket = new Socket(hostName, portNumber);

                BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
                PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);


        ) {

            System.out.println("Connected");
            Double[][] test2 = new Double[5][2];
            test2[1][1] = 0.1;
            test2[1][0] = 0.2;
            test2[2][1] = 0.2;
            test2[2][0] = 0.2;
            test2[3][1] = 0.1;
            test2[3][0] = 0.2;
            test2[4][1] = 0.2;
            test2[4][0] = 0.2;
            test2[0][1] = 0.2;
            test2[0][0] = 0.2;


            System.out.println("A");
            out.println(new JSONArray(test2).toString());
            System.out.println("B");


            long t = System.currentTimeMillis();
            long end = t + 15000;


            while (System.currentTimeMillis() < end) {
                String response;
                while ((response = in.readLine()) != null) {
                    System.out.println("receiving");
                    System.out.println( response );

                }


            }


            //listen for input continuously? 


            //clientSocket.close();
        } catch (JSONException e) {
            e.printStackTrace();
        }


    }


}

python 的输出是:

data well received!: 
('[[0.2,0.2],[0.2,0.1],[0.2,0.2],[0.2,0.1],[0.2,0.2]]',)
[[ 0.2  0.2]
 [ 0.2  0.1]
 [ 0.2  0.2]
 [ 0.2  0.1]
 [ 0.2  0.2]]
Preparing to send this:
[[ 1.5  2.   3. ]
 [ 4.   5.   6. ]]
closed
waiting for a connection
connection from ('127.0.0.1', 40074)

Java 的输出:

A
B

问题是 sendArray = np.array( [ (1.5,2,3), (4,5,6) ] ); java 永远不会收到。我觉得我缺少一些简单的东西来让它听...感谢您的帮助。

Answer 1

发生这种情况是因为您的 Java 代码正在阻塞。看看 B 是如何不打印到您的日志中的？这是因为它没有执行，因为这部分正在等待刷新命令:out.println(new JSONArray(test2).toString());。你需要做的是 out.flush(); 所以它会继续。