本文所述示例程序是基于Linux平台的socket网络编程，实现文件传输功能。该示例是基于TCP流协议实现的socket网络文件传输程序。采用C语言编写。最终能够实现传输任何格式文件的文件传输程序。

具体实现代码如下：

Server端代码如下：

/************************************************************************* > 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) { // 声明并初始化一个服务器端的socket地址结构 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); // 创建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)); // 绑定socket和socket地址结构 if(-1 == (bind(server_socket_fd, (struct sockaddr*)&server_addr, sizeof(server_addr)))) { perror("Server Bind Failed:"); exit(1); } // socket监听 if(-1 == (listen(server_socket_fd, LENGTH_OF_LISTEN_QUEUE))) { perror("Server Listen Failed:"); exit(1); } while(1) { // 定义客户端的socket地址结构 struct sockaddr_in client_addr; socklen_t client_addr_length = sizeof(client_addr); // 接受连接请求，返回一个新的socket(描述符)，这个新socket用于同连接的客户端通信 // accept函数会把连接到的客户端信息写到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函数接收数据到缓冲区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; } // 然后从buffer(缓冲区)拷贝到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("%sn", file_name); // 打开文件并读取文件数据 FILE *fp = fopen(file_name, "r"); if(NULL == fp) { printf("File:%s Not Foundn", file_name); } else { bzero(buffer, BUFFER_SIZE); int length = 0; // 每读取一段数据，便将其发送给客户端，循环直到文件读完为止 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); } // 关闭文件 fclose(fp); printf("File:%s Transfer Successful!n", file_name); } // 关闭与客户端的连接 close(new_server_socket_fd); } // 关闭监听用的socket close(server_socket_fd); return 0; }

Client端代码如下：

/************************************************************************* > 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() { // 声明并初始化一个客户端的socket地址结构 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); // 创建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); } // 绑定客户端的socket和客户端的socket地址结构 非必需 if(-1 == (bind(client_socket_fd, (struct sockaddr*)&client_addr, sizeof(client_addr)))) { perror("Client Bind Failed:"); exit(1); } // 声明一个服务器端的socket地址结构，并用服务器那边的IP地址及端口对其进行初始化，用于后面的连接 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); // 向服务器发起连接，连接成功后client_socket_fd代表了客户端和服务器的一个socket连接 if(connect(client_socket_fd, (struct sockaddr*)&server_addr, server_addr_length) < 0) { perror("Can Not Connect To Server IP:"); exit(0); } // 输入文件名 并放到缓冲区buffer中等待发送 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)); // 向服务器发送buffer中的数据 if(send(client_socket_fd, buffer, BUFFER_SIZE, 0) < 0) { perror("Send File Name Failed:"); exit(1); } // 打开文件，准备写入 FILE *fp = fopen(file_name, "w"); if(NULL == fp) { printf("File:t%s Can Not Open To Writen", file_name); exit(1); } // 从服务器接收数据到buffer中 // 每接收一段数据，便将其写入文件中，循环直到文件接收完并写完为止 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 Failedn", file_name); break; } bzero(buffer, BUFFER_SIZE); } // 接收成功后，关闭文件，关闭socket printf("Receive File:t%s From Server IP Successful!n", file_name); close(fp); close(client_socket_fd); return 0; }

该程序备有较为详尽的注释，相信不难理解。感兴趣的朋友可以在此基础上尝试一些功能的扩展，使其功能更加强大。