本文所述示例程序是基于Linux平臺的socket網(wǎng)絡(luò)編程，實(shí)現(xiàn)文件傳輸功能。該示例是基于TCP流協(xié)議實(shí)現(xiàn)的socket網(wǎng)絡(luò)文件傳輸程序。采用C語言編寫。最終能夠?qū)崿F(xiàn)傳輸任何格式文件的文件傳輸程序。

具體實(shí)現(xiàn)代碼如下：

Server端代碼如下：

/************************************************************************* 
  > File Name: Server.c 
  > Author: SongLee 
 ************************************************************************/ 
 
#include<netinet/in.h> // sockaddr_in 
#include<sys/types.h>  // socket 
#include<sys/socket.h> // socket 
#include<stdio.h>    // printf 
#include<stdlib.h>   // exit 
#include<string.h>   // bzero 
 
#define SERVER_PORT 8000 
#define LENGTH_OF_LISTEN_QUEUE 20 
#define BUFFER_SIZE 1024 
#define FILE_NAME_MAX_SIZE 512 
 
int main(void) 
{ 
  // 聲明并初始化一個(gè)服務(wù)器端的socket地址結(jié)構(gòu) 
  struct sockaddr_in server_addr; 
  bzero(&server_addr, sizeof(server_addr)); 
  server_addr.sin_family = AF_INET; 
  server_addr.sin_addr.s_addr = htons(INADDR_ANY); 
  server_addr.sin_port = htons(SERVER_PORT); 
 
  // 創(chuàng)建socket，若成功，返回socket描述符 
  int server_socket_fd = socket(PF_INET, SOCK_STREAM, 0); 
  if(server_socket_fd < 0) 
  { 
    perror("Create Socket Failed:"); 
    exit(1); 
  } 
  int opt = 1; 
  setsockopt(server_socket_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)); 
 
  // 綁定socket和socket地址結(jié)構(gòu) 
  if(-1 == (bind(server_socket_fd, (struct sockaddr*)&server_addr, sizeof(server_addr)))) 
  { 
    perror("Server Bind Failed:"); 
    exit(1); 
  } 
   
  // socket監(jiān)聽 
  if(-1 == (listen(server_socket_fd, LENGTH_OF_LISTEN_QUEUE))) 
  { 
    perror("Server Listen Failed:"); 
    exit(1); 
  } 
 
  while(1) 
  { 
    // 定義客戶端的socket地址結(jié)構(gòu) 
    struct sockaddr_in client_addr; 
    socklen_t client_addr_length = sizeof(client_addr); 
 
    // 接受連接請求，返回一個(gè)新的socket(描述符)，這個(gè)新socket用于同連接的客戶端通信 
    // accept函數(shù)會把連接到的客戶端信息寫到client_addr中 
    int new_server_socket_fd = accept(server_socket_fd, (struct sockaddr*)&client_addr, &client_addr_length); 
    if(new_server_socket_fd < 0) 
    { 
      perror("Server Accept Failed:"); 
      break; 
    } 
 
    // recv函數(shù)接收數(shù)據(jù)到緩沖區(qū)buffer中 
    char buffer[BUFFER_SIZE]; 
    bzero(buffer, BUFFER_SIZE); 
    if(recv(new_server_socket_fd, buffer, BUFFER_SIZE, 0) < 0) 
    { 
      perror("Server Recieve Data Failed:"); 
      break; 
    } 
 
    // 然后從buffer(緩沖區(qū))拷貝到file_name中 
    char file_name[FILE_NAME_MAX_SIZE+1]; 
    bzero(file_name, FILE_NAME_MAX_SIZE+1); 
    strncpy(file_name, buffer, strlen(buffer)>FILE_NAME_MAX_SIZE?FILE_NAME_MAX_SIZE:strlen(buffer)); 
    printf("%s\n", file_name); 
 
    // 打開文件并讀取文件數(shù)據(jù) 
    FILE *fp = fopen(file_name, "r"); 
    if(NULL == fp) 
    { 
      printf("File:%s Not Found\n", file_name); 
    } 
    else 
    { 
      bzero(buffer, BUFFER_SIZE); 
      int length = 0; 
      // 每讀取一段數(shù)據(jù)，便將其發(fā)送給客戶端，循環(huán)直到文件讀完為止 
      while((length = fread(buffer, sizeof(char), BUFFER_SIZE, fp)) > 0) 
      { 
        if(send(new_server_socket_fd, buffer, length, 0) < 0) 
        { 
          printf("Send File:%s Failed./n", file_name); 
          break; 
        } 
        bzero(buffer, BUFFER_SIZE); 
      } 
 
      // 關(guān)閉文件 
      fclose(fp); 
      printf("File:%s Transfer Successful!\n", file_name); 
    } 
    // 關(guān)閉與客戶端的連接 
    close(new_server_socket_fd); 
  } 
  // 關(guān)閉監(jiān)聽用的socket 
  close(server_socket_fd); 
  return 0; 
}

Client端代碼如下：

/************************************************************************* 
  > File Name: Client.c 
  > Author: SongLee 
 ************************************************************************/ 
 
#include<netinet/in.h>  // sockaddr_in 
#include<sys/types.h>  // socket 
#include<sys/socket.h>  // socket 
#include<stdio.h>    // printf 
#include<stdlib.h>    // exit 
#include<string.h>    // bzero 
 
#define SERVER_PORT 8000 
#define BUFFER_SIZE 1024 
#define FILE_NAME_MAX_SIZE 512 
 
int main() 
{ 
  // 聲明并初始化一個(gè)客戶端的socket地址結(jié)構(gòu) 
  struct sockaddr_in client_addr; 
  bzero(&client_addr, sizeof(client_addr)); 
  client_addr.sin_family = AF_INET; 
  client_addr.sin_addr.s_addr = htons(INADDR_ANY); 
  client_addr.sin_port = htons(0); 
 
  // 創(chuàng)建socket，若成功，返回socket描述符 
  int client_socket_fd = socket(AF_INET, SOCK_STREAM, 0); 
  if(client_socket_fd < 0) 
  { 
    perror("Create Socket Failed:"); 
    exit(1); 
  } 
 
  // 綁定客戶端的socket和客戶端的socket地址結(jié)構(gòu) 非必需 
  if(-1 == (bind(client_socket_fd, (struct sockaddr*)&client_addr, sizeof(client_addr)))) 
  { 
    perror("Client Bind Failed:"); 
    exit(1); 
  } 
 
  // 聲明一個(gè)服務(wù)器端的socket地址結(jié)構(gòu)，并用服務(wù)器那邊的IP地址及端口對其進(jìn)行初始化，用于后面的連接 
  struct sockaddr_in server_addr; 
  bzero(&server_addr, sizeof(server_addr)); 
  server_addr.sin_family = AF_INET; 
  if(inet_pton(AF_INET, "127.0.0.1", &server_addr.sin_addr) == 0) 
  { 
    perror("Server IP Address Error:"); 
    exit(1); 
  } 
  server_addr.sin_port = htons(SERVER_PORT); 
  socklen_t server_addr_length = sizeof(server_addr); 
 
  // 向服務(wù)器發(fā)起連接，連接成功后client_socket_fd代表了客戶端和服務(wù)器的一個(gè)socket連接 
  if(connect(client_socket_fd, (struct sockaddr*)&server_addr, server_addr_length) < 0) 
  { 
    perror("Can Not Connect To Server IP:"); 
    exit(0); 
  } 
 
  // 輸入文件名 并放到緩沖區(qū)buffer中等待發(fā)送 
  char file_name[FILE_NAME_MAX_SIZE+1]; 
  bzero(file_name, FILE_NAME_MAX_SIZE+1); 
  printf("Please Input File Name On Server:\t"); 
  scanf("%s", file_name); 
 
  char buffer[BUFFER_SIZE]; 
  bzero(buffer, BUFFER_SIZE); 
  strncpy(buffer, file_name, strlen(file_name)>BUFFER_SIZE?BUFFER_SIZE:strlen(file_name)); 
   
  // 向服務(wù)器發(fā)送buffer中的數(shù)據(jù) 
  if(send(client_socket_fd, buffer, BUFFER_SIZE, 0) < 0) 
  { 
    perror("Send File Name Failed:"); 
    exit(1); 
  } 
 
  // 打開文件，準(zhǔn)備寫入 
  FILE *fp = fopen(file_name, "w"); 
  if(NULL == fp) 
  { 
    printf("File:\t%s Can Not Open To Write\n", file_name); 
    exit(1); 
  } 
 
  // 從服務(wù)器接收數(shù)據(jù)到buffer中 
  // 每接收一段數(shù)據(jù)，便將其寫入文件中，循環(huán)直到文件接收完并寫完為止 
  bzero(buffer, BUFFER_SIZE); 
  int length = 0; 
  while((length = recv(client_socket_fd, buffer, BUFFER_SIZE, 0)) > 0) 
  { 
    if(fwrite(buffer, sizeof(char), length, fp) < length) 
    { 
      printf("File:\t%s Write Failed\n", file_name); 
      break; 
    } 
    bzero(buffer, BUFFER_SIZE); 
  } 
 
  // 接收成功后，關(guān)閉文件，關(guān)閉socket 
  printf("Receive File:\t%s From Server IP Successful!\n", file_name); 
  close(fp); 
  close(client_socket_fd); 
  return 0; 
}

該程序備有較為詳盡的注釋，相信不難理解。感興趣的朋友可以在此基礎(chǔ)上嘗試一些功能的擴(kuò)展，使其功能更加強(qiáng)大。

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