套接字通信，Java客戶端C服務器

Question

我想通過套接字通信一個Java客戶端和一個C服務器 所有似乎工作正常，如果我嘗試服務器在命令行上使用nc連接或如果我使用nc作爲服務器並連接到我的Java客戶端，但是當我嘗試連接Java Client和C服務器時，它不起作用。

客戶端啓動連接，併發送消息，消息被服務器接收，但服務器的響應永遠不會到達客戶端。

服務器代碼：

#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; 


} 

客戶端代碼：

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(); 

    } 
} 

Answer 1

readLine()塊，直到連接已經shutdown()或close() d或者它收到一個新的行\n，從未由服務器發送。