java - C 套接字服务器，Java 套接字客户端 : BLOCKING!

Question

我将我的代码粘贴到一个简单的 C 套接字服务器和一个 Java 客户端。

我在 Java 中使用 write 方法逐字符发送。然而，在发送完字符 block (此处为“h”、“e”、“y”)后，Java 客户端被阻止发送，因为 C 服务器不回复它:(

我假设发送空字符(从 Java 写入)会在 C 端停止 recv 时存在一些问题。

如有任何帮助，我们将不胜感激。

C 服务器:

#include <stdio.h>   /* standard in and output*/
#include <sys/socket.h> /* for socket() and socket functions*/
#include <arpa/inet.h>  /* for sockaddr_in and inet_ntoa() */
#include <stdlib.h>    
#include <string.h>     
#include <unistd.h>     /* for close() */


int main(int argc, char *argv[]){
 int sock, connected, bytes_received, true = 1;  
    char recv_data;      
 char replyBuffer[32];

    struct sockaddr_in server_addr,client_addr;    
    int sin_size;       
    if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
        perror("Socket");
        exit(1);
    }

    if (setsockopt(sock,SOL_SOCKET,SO_REUSEADDR,&true,sizeof(int)) == -1) {
        perror("Setsockopt");
        exit(1);
    }

    server_addr.sin_family = AF_INET;         
    server_addr.sin_port = htons(2400);     
    server_addr.sin_addr.s_addr = INADDR_ANY; 
    bzero(&(server_addr.sin_zero),8); 

    if (bind(sock, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1) {
        perror("Unable to bind");
            exit(1);
    }

    if (listen(sock, 5) == -1) {
        perror("Listen");
        exit(1);
    }

 printf("\nTCPServer Waiting for client on port 2400");

   while(1){  
        sin_size = sizeof(client_addr);
        connected = accept(sock, (struct sockaddr *)&client_addr,&sin_size);
        printf("\n Got a connection from (%s , %d)",inet_ntoa(client_addr.sin_addr),ntohs(client_addr.sin_port));


       while ((bytes_received = recv(connected,&recv_data,1,0)) > 0){
  printf("\nrecv= %c\n", recv_data);
  }
  int success = 1;
  sprintf(replyBuffer, "%d", success); 
  printf("reply buffer = %s\n", replyBuffer);
  if (send(connected, replyBuffer, strlen(replyBuffer), 0) == -1)
    perror("send() failed"); 
    success = 0;
  close(connected);
 }
}

Java 客户端:

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

public class Client1
{
 public static void main(String[] args) throws IOException {
  if (args.length < 2) {
   System.err.println("Usage: java Client1 <IP address> <Port number>");
   System.exit(0);
  }
  BufferedReader in = null;
  OutputStream out = null;
  Socket sock = null;

  try {
   sock = new Socket(args[0], Integer.parseInt(args[1]));
   out = sock.getOutputStream();
   in = new BufferedReader(new InputStreamReader(sock.getInputStream()));

    String line = "hey";
    String responseline = null;
char[] strArray;
strArray = line.toCharArray();

while (true) {
for( int index = 0; index < strArray.length; index++){
 out.write(strArray[index]);
}
out.flush();
System.out.println("data sent " );
System.out.println("val returned"+in.readLine());
   }
  }
  catch (IOException ioe) {
   System.err.println(ioe);
  }
  finally {
   if (in != null)
    in.close();

   if (out != null)
    out.close();
   if (sock != null)
    sock.close();
  }
 }
}

Answer 1

来自 BufferedReader.readLine() 的 javadoc

Read a line of text. A line is considered to be terminated by any one of a line feed ('\n'), a carriage return ('\r'), or a carriage return followed immediately by a linefeed. 

这就是它阻塞的原因(没有 lf，没有 cr，没有 crlf)

[编辑]
您需要创建一个 C 程序可以理解的 EOL 指示器(就像 java 客户端中的 readLine() 一样。让该指示器为 '\n'(如果没有别的，为了保持一致性)
在 Client.java 中，将 '\n' 附加到您发送的字符串。
在 tst.c 中，测试 '\n'，当它被接收时，从 recv() 循环中跳出
[/edit]