[英]C socket server, Java socket client : BLOCKING!
I am pasting my code for a simple socket server in C and a Java client. 我将代码粘贴到C和Java客户端中的简单套接字服务器上。
I use write method sending character by character in Java. 我使用写方法在Java中逐个字符发送。 However after the chunk of characters are sent(here, 'h', 'e', 'y') , the Java client is send blocked as the C server does not reply to it :(
但是,在发送了字符块之后(此处为“ h”,“ e”,“ y”),由于C服务器未回复它,Java客户端被阻止发送:(
I am assuming there is some problem with sending a null character(from the Java write) that would stop the recv at the C side. 我假设发送一个空字符(来自Java写)会在C端停止recv时出现问题。
Any help would be greatly appreciated. 任何帮助将不胜感激。
C server: 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 Client: 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();
}
}
}
from javadoc for BufferedReader.readLine() 从javadoc中获取BufferedReader.readLine()
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.
That's why it blocks (no lf, no cr, no crlf) 这就是为什么它会阻塞(没有lf,没有cr,没有crlf)
[edit] [编辑]
You need to create an EOL indicator that the C program understands (just like readLine() in the java client. Let that indicator be '\\n' (for consistency if nothing else) 您需要创建一个C程序可以理解的EOL指标(就像Java客户端中的readLine()一样。让该指标为'\\ n'(为了保持一致,如果没有其他要求)
In Client.java, append '\\n' to your sent string. 在Client.java中,将'\\ n'附加到您发送的字符串中。
In tst.c, test for '\\n', when it's received, break from the recv() loop 在tst.c中,测试是否收到\\ n,然后从recv()循环中断开
[/edit] [/编辑]
Your assumption of the problem is correct. 您对问题的假设是正确的。 The
recv
call will always return a value greater than zero. recv
调用将始终返回大于零的值。 I suggest using a special character to designate the end of the text and terminating the recv()
loop when that character is read. 我建议使用特殊字符来指定文本的结尾,并在读取该字符时终止
recv()
循环。
client change to 客户更改为
out.write(line.getBytes());
server change to 服务器更改为
char recv_data[32];
recv(connect,recv_data,32,0);
In my opinion there is an error of your server code.If you compile your server code on linux, there be an error. 我认为您的服务器代码有错误。如果您在Linux上编译服务器代码,则会有错误。 The type of sin_size should be socklen_t.
sin_size的类型应为socklen_t。 or you will see an error information "invalid conversion from int* to socklen_t"
否则您将看到错误信息“从int *到socklen_t的无效转换”
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