我正在尝试通过套接字与 Java 客户端和 C 服务器进行通信 如果我尝试在命令行上使用 nc 连接服务器，或者如果我使用 nc 作为服务器并与我的 Java 客户端连接，那么一切似乎都可以正常工作，但是当我尝试连接Java客户端和C服务器它不起作用。
客户端启动连接并发送消息，服务器接收到消息，但服务器的响应永远不会到达客户端。
服务器代码：
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <strings.h>
#include <unistd.h>
int main( int argc, char *argv[] )
{
int sockfd, clisockfd, portno;
char * start = "hello";
char * end = "bye";
socklen_t clilen;
char buffer[256];
char contentBuffer[255];
struct sockaddr_in serv_addr, cli_addr;
int n;
//int optval;
/* First call to socket() function */
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
{
perror("ERROR opening socket");
return(1);
}
/* Initialize socket structure */
bzero((char *) &serv_addr, sizeof(serv_addr));
portno = 5000;
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = INADDR_ANY;
serv_addr.sin_port = htons(portno);
if (bind(sockfd, (struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0)
{
perror("ERROR on binding");
return(1);
}
listen(sockfd,5);
clilen = (socklen_t) sizeof(cli_addr);
clisockfd = accept(sockfd, (struct sockaddr *)&cli_addr, &clilen);
if (clisockfd < 0)
{
perror("ERROR on accept");
return(1);
}
while (strcmp(end, contentBuffer) !=0)
{
bzero(buffer,256);
bzero(contentBuffer,255);
/* If connection is established then start communicating */
n = read( clisockfd,buffer,255 );
if (n < 0)
{
perror("ERROR reading from socket");
return(1);
}
strncpy(contentBuffer,buffer,strlen(buffer) - 1);
if (strcmp(start, contentBuffer) ==0)
{
printf("command: %s\n",buffer);
n = write(clisockfd,"Roger that",11);
if (n < 0)
{
perror("ERROR writing to socket");
return(1);
}
}
else
{
printf("Unknown command: %s\n",buffer);
n = write(clisockfd,"ERRCmd",7);
if (n < 0)
{
perror("ERROR writing to socket");
return(1);
}
}
}
close(sockfd);
return 0;
}
客户代码：
import java.io.*;
import java.net.*;
public class Cliente {
public static void main(String[] args) throws IOException {
if (args.length != 2) {
System.err.println(
"Usage: java EchoClient <host name> <port number>");
System.exit(1);
}
String hostName = args[0];
int portNumber = Integer.parseInt(args[1]);
Socket firstSocket = new Socket(hostName, portNumber);
PrintWriter out = new PrintWriter(firstSocket.getOutputStream(), true);
BufferedReader in = new BufferedReader(new InputStreamReader(firstSocket.getInputStream()));
BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));
String userInput;
while ((userInput = stdIn.readLine()) != null)
{
out.println(userInput);
System.out.println("received: " + in.readLine());
}
in.close();
stdIn.close();
firstSocket.close();
}
}