A simple client/server communication program

---------------- client.c ----------------------------------------

#>:cat client.c
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <netdb.h>
#include <resolv.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

#define MAXBUF 1024

int main(int argc, char **argv)
{
        int sockfd, len;
        struct hostent     *host = NULL;
        struct sockaddr_in dest;

        if (argc != 3) {
                printf("Usage: %s address port/n",argv[0]);
                exit(0);
        }

        if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
                perror("Socket");
                exit(errno);
        }


        bzero(&dest, sizeof(dest));

        host = gethostbyname(argv[1]);
        if (host == NULL)
        {
                perror("Socket");
                exit(errno);
        }

        dest.sin_family = AF_INET;
        dest.sin_port = htons(atoi(argv[2]));
        //dest.sin_addr.s_addr = inet_addr(argv[1]);
        memcpy(&dest.sin_addr, host->h_addr, host->h_length);


        if (connect(sockfd, (struct sockaddr *) &dest, sizeof(dest)) != 0) {
                perror("Connect");
                exit(errno);
        }


        char buffer[MAXBUF + 1];

        bzero(buffer, MAXBUF + 1);
        strcpy(buffer, "GET");
        len = send(sockfd, buffer, strlen(buffer), 0);
        if (len < 0)
                printf("send message '%s' failed, with error code: %d, error message:'%s'./n",
                                buffer, errno, strerror(errno));
        else
                printf("send message '%s' succeed, send length is %d./n", buffer, len);

        bzero(buffer, MAXBUF + 1);
        len = recv(sockfd, buffer, MAXBUF, 0);
        if (len > 0)
                printf("receive message '%s' success, total %d bytes data/n", buffer, len);
        else
                printf("receive message failed, with error code: %d, error message: '%s'./n",
                                errno, strerror(errno));

        close(sockfd);
        return 0;
}

 

---------------- server.c ----------------------------------------

#>:cat server.c

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <unistd.h>
#include <arpa/inet.h>

#define MAXBUF 1024

int main(int argc, char **argv)
{
        int sockfd, new_fd;
        socklen_t len;
        struct sockaddr_in my_addr, their_addr;
        unsigned int myport, lisnum;
        char buf[MAXBUF + 1];

        if (argc != 2) {
                printf("Usage %s port/n",argv[0]);
                exit(0);
        }

        myport = atoi(argv[1]);

        if ((sockfd = socket(PF_INET, SOCK_STREAM, 0)) == -1) {
                perror("socket");
                exit(1);
        }
        else printf("socket created/n");

        bzero(&my_addr, sizeof(my_addr));
        my_addr.sin_family = PF_INET;
        my_addr.sin_port = htons(myport);
        //my_addr.sin_addr.s_addr = inet_addr(argv[3]);
        my_addr.sin_addr.s_addr = INADDR_ANY;

        if (bind(sockfd, (struct sockaddr *) &my_addr, sizeof(struct sockaddr)) == -1) {
                perror("bind");
                exit(1);
        }
        else printf("binded/n");

        if (listen(sockfd, lisnum) == -1) {
                perror("listen");
                exit(1);
        }
        else printf("begin listen/n");

        while(1) {
                len = sizeof(struct sockaddr);
                if ((new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &len)) == -1) {
                        perror("accept");
                        exit(errno);
                }
                else
                        printf("server: got connection from %s, port %d, socket %d/n",inet_ntoa(their_addr.sin_addr), ntohs(their_addr.sin_port), new_fd);


/*
                bzero(buf, MAXBUF + 1);
                strcpy(buf, "/n");

                len = send(new_fd, buf, strlen(buf), 0);
                if(len < 0) {
                        printf("'%s',%d,'%s'/n", buf, errno, strerror(errno));
                }
                        else printf("'%s',%d/n", buf, len);

                bzero(buf, MAXBUF + 1);

                len = recv(new_fd, buf, MAXBUF, 0);
                if(len > 0) printf("'%s'%d/n", buf, len);
                else printf("%d'%s'/n", errno, strerror(errno));
*/

        }

        close(sockfd);
        return 0;
}

 

# cc client.c -o client -lsocket -lnsl

# cc server.c -o server -lsocket -lnsl

# 要实现非阻塞通信方式, 可以参考系统调用select/poll的用法, http://bbs2.chinaunix.net/archiver/tid-1326519.html

 

 

---------------- Client.java ----------------------------------------

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;


public class Client
{
    /**
     * Usage:
     *     $> program host port
     * @param args
     */
    public static void main(String[] args) {
       
        if (args.length != 2)
        {
            System.out.println("Usage:/n/t$> program host port");
            System.exit(0);
        }
       
       
        String host = args[0];
       
        int port = Integer.parseInt(args[1]);
       
        Socket s = null;
        try {
            s = new Socket (host, port);
        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
       

        //InputStreamReader isr = null;
       
        BufferedReader reader = null;
        PrintWriter writer = null;
       
        try {
            reader = new BufferedReader (new InputStreamReader (s.getInputStream ()));
            writer = new PrintWriter (s.getOutputStream (), true);

           
            BufferedReader cmdReader = new BufferedReader (new InputStreamReader (System.in));
            String sent = null;
            while(true)
            {
                System.out.print("message(q,quit)> ");

                sent = cmdReader.readLine();
                if (sent.equals("q") || sent.equals("quit"))
                    break;
               
                if (sent.length() <= 0)
                    continue;
               
                //System.out.println("send message: " + sent);
                writer.println(sent);
               
                String received = reader.readLine ();
                if (received != null) {
                    System.out.println("receive message: " + received);
                }
            }
           
        }     catch (IOException e) {
            e.printStackTrace();
        } finally {
            System.out.println ("Closing Connection.../n");
            try {
                reader.close();
                writer.close();
                s.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
           
        }
    }

}

 

---------------- Server.java ----------------------------------------

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketAddress;
import java.util.Calendar;


class Server {

    public static void main(String[] args) throws IOException {

        System.out.println("Server starting.../n");
       
        ServerSocket server = new ServerSocket(10000);

        while (true) {
            Socket s = server.accept();
            System.out.println("Accepting Connection.../n");

            SocketAddress ra = s.getRemoteSocketAddress();
            SocketAddress la = s.getLocalSocketAddress();
           
            InetSocketAddress ria = (InetSocketAddress) ra;
            InetSocketAddress lia = (InetSocketAddress) la;
           
            System.out.println("Local Address:"+lia.getAddress()+":"+lia.getPort());
            System.out.println("Remote Address:"+ria.getAddress()+":"+ria.getPort());
           
            // Start a thread to handle the connection.
            new ServerThread(s).start();
        }

    }
}

class ServerThread extends Thread {

    private Socket s;

    ServerThread(Socket s) {
        this.s = s;
    }

    public void run ()
    {
        BufferedReader reader = null;
        PrintWriter writer = null;
        try
        {

            reader = new BufferedReader (new InputStreamReader (s.getInputStream ()));
            writer = new PrintWriter (s.getOutputStream (), true);

            do
            {
                String cmd = reader.readLine ();

                if (cmd != null) {
                    System.out.println("Receive message: [" + cmd + "], send back with double.");
                    writer.println (cmd+":"+cmd);
                } else {
                    break;
                }
            } while (true);
           
            // System.out.println("Need to quit.");
           
        } catch (IOException e) {
            System.out.println ("Exception : " + e.toString ());       
        } finally {
            System.out.println ("Closing Connection.../n");
            try
            {
                if (reader != null)
                    reader.close ();
                if (writer != null)
                    writer.close ();
                if (s != null)
                    s.close ();
            } catch (Exception e){}
        }
    } // run
}