从 C 套接字客户端读取输入到 Java 套接字服务器

Question

我有 2 个套接字客户端和 2 个套接字服务器，每个都使用 C 和 Java，所有运行在我的本地计算机上作为进程。

除了C套接字和Java服务器外，他们都可以成功地相互交谈。他们连接成功，但是当我在 C 客户端中键入输入时，回车键没有完成消息并将其发送到 Java 服务器，就像与 C 服务器通信时一样。

如有任何见解，我们将不胜感激。

Java 服务器：

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

public class SimpleServer extends Thread
{
   private ServerSocket serverSocket;
   String clientmsg = "";

   public SimpleServer(int port) throws IOException
   {
      serverSocket = new ServerSocket(port);
      serverSocket.setSoTimeout(10000);
   }

    public void run()
    {
        while(true)
        {
            try
            {
                System.out.println("Waiting for client on port " + serverSocket.getLocalPort() + "...");
                Socket server = serverSocket.accept();
                System.out.println("Just connected to " + server.getRemoteSocketAddress());
                DataInputStream in = new DataInputStream(server.getInputStream());
                System.out.println(in.readUTF());
                DataOutputStream out = new DataOutputStream(server.getOutputStream());
                out.writeUTF("Thank you for connecting to "
                + server.getLocalSocketAddress() + "\nGoodbye!");
                server.close();
            }

            catch(SocketTimeoutException s)
            {
                System.out.println("Socket timed out!");
                break;
            }

            catch(IOException e)
            {
                e.printStackTrace();
                break;
            }
        }
    }
    public static void main(String [] args)
    {
        int port = Integer.parseInt(args[0]);
        try
        {
            Thread t = new SimpleServer(port);
            t.start();
        }

        catch(IOException e)
        {
            e.printStackTrace();
        }
    }
}

C 客户端：

#include <stdio.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <string.h>
#include <netdb.h>

void error(char *msg) 
{
    perror(msg);
    exit(0);
}

int main(int argc, char *argv[])
{
    int sockfd, portno;
    struct sockaddr_in serv_addr;
    struct hostent *server;
    int n;
    char buffer[256];

    if (argc < 3)
    {
        error("ERROR, no port provided");
    }

    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    if (sockfd < 0)
    {
        error("ERROR opening socket");
    }

    server = gethostbyname(argv[1]);

    if (server == NULL)
    {
        error("ERROR, host not found\n");
    }

    bzero((char *) &serv_addr, sizeof(serv_addr));
    portno = atoi(argv[2]);
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(portno);

    bcopy((char *)server->h_addr, (char *)&serv_addr.sin_addr.s_addr, server->h_length);

    if (connect(sockfd,(struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
    {
        error("ERROR connecting to server");
    }

    printf("Enter a message for the server: ");

    bzero(buffer,256);
    fgets(buffer,sizeof(buffer),stdin);
    n = write(sockfd,buffer,strlen(buffer));

    if (n < 0)
    {/
        error("ERROR writing to socket");
    }

    bzero(buffer,256);
    n = read(sockfd,buffer,255);

    if (n < 0)
    {
        error("ERROR reading from socket");
    }

    printf("%s\n", buffer);
    return 0;
}

Answer 1

来自 readUTF() 文档：

First, two bytes are read and used to construct an unsigned 16-bit integer in exactly the manner of the readUnsignedShort method . This integer value is called the UTF length and specifies the number of additional bytes to be read.

在您的 C 客户端中，您没有发送这两个字节。当然，writeUTF().

也是如此

Answer 2

要由 readUTF() 读取的数据必须由 writeUTF(), 或可以产生相同结果的东西发送 protoco:l：请参阅 Javadoc。由于您的发件人是 C，这是不切实际的，因此您应该使用不同的读法 API，例如 readLine(),，并在发件人处进行适当的调整。

Answer 3

我建议使用 BufferedReader 和 PrintWriter，如下所示，

BufferedReader in = new BufferedReader( new InputStreamReader(socket.getInputStream())); // Bufferreader from socket
PrintWriter out = new PrintWriter(socket.getOutputStream(), true); // printwriter from socket

您可以简单地将它们用作 ,

in.readLine(); // read a line

out.println(); // write a line

所以更新后的代码看起来像，

Socket server = serverSocket.accept();

System.out.println("Just connected to " + server.getRemoteSocketAddress());

BufferedReader in = new  BufferedReader( new InputStreamReader(socket.getInputStream()));

System.out.println(in.readline());

PrintWriter out = new PrintWriter(server.getOutputStream());

out.println("Thank you for connecting to ");

此外，如果我是正确的，这种方法将满足 Java 和 C 的线路终端条件。

从 C 套接字客户端读取输入到 Java 套接字服务器

Reading input from C socket client to Java socket server

java

c

sockets

client