Socket编程-文件传输功能的实现

学习一下用socket进行文件传输，从服务器下载文件。

运行结果（客户端）：

成功从服务器下载MV“起风了 ” 。

源代码：

服务器端：

#include <stdio.h>
#include <WinSock2.h>

#pragma comment(lib, "ws2_32.lib")   //加载 ws2_32.dll

const int BUFSIZE = 1024;

int main()
{
	//先检查文件是否存在
	//文件名
	char *filename = "D:\\send.mp4";
	//以二进制方式打开文件
	FILE *fp = fopen(filename, "rb");

	if(fp == NULL)
	{
		printf("Cannot open file, press any key to exit!\n");
        system("pause");
        exit(0);
	}

	WSADATA wsaData;
	WSAStartup(MAKEWORD(2,2), &wsaData);

	//创建套接字
	SOCKET servSock = socket(AF_INET, SOCK_STREAM, 0);
	
	//绑定套接字
	sockaddr_in servAddr;
	//每个字节都用0填充
	memset(&servAddr, 0, sizeof(servAddr));
	//使用IPv4地址
	servAddr.sin_family = AF_INET;
	//具体的IP地址
	servAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
	//端口
	servAddr.sin_port = htons(1234);
	bind(servSock, (sockaddr *)&servAddr, sizeof(servAddr));

	//进入监听状态
	listen(servSock, 20);

	//接收客户端请求
	sockaddr clntAddr;
	int nSize = sizeof(sockaddr);
	SOCKET clntSock = accept(servSock, &clntAddr, &nSize);

	//缓冲区
	char buffer[BUFSIZE] = {0};
	int nCount = 0;
	//循环发送数据，直到文件结尾
	while( (nCount = fread(buffer, 1, BUFSIZE, fp)) > 0)
		send(clntSock, buffer, nCount, 0);
	//文件读取完毕，断开输出流，向客户端发送FIN包
	shutdown(clntSock, SD_SEND);
	//阻塞，等待客户端接收完毕。
	recv(clntSock, buffer, BUFSIZE, 0);

	fclose(fp);
	//关闭套接字
	closesocket(clntSock);
	closesocket(servSock);

	//终止 DLL 的使用
	WSACleanup();
	return 0;
}

客户端：

#include <stdio.h>
#include <WinSock2.h>

#pragma comment(lib, "ws2_32.lib")    //加载 ws2_32.dll

const int BUFSIZE = 1024;

int main()
{
	//先输入文件名，看文件是否能创建成功
	//文件名
	char filename[100] = {0};
	printf("Input filename to save: ");
	gets(filename);
	//以二进制方式打开（创建）文件
	FILE *fp = fopen(filename, "wb");
	if(fp == NULL)
	{
		printf("Cannot open file, press any key to exit!\n");
        system("pause");
        exit(0);
	}

	//初始化DLL
	WSADATA wsaData;
	WSAStartup(MAKEWORD(2,2), &wsaData);

	//创建套接字
	SOCKET clntSock = socket(AF_INET, SOCK_STREAM, 0);

	//向服务器发起请求
	sockaddr_in clntAddr;
	//每个字节都用0填充
	memset(&clntAddr, 0, sizeof(clntAddr));
	clntAddr.sin_family = AF_INET;
	clntAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
	clntAddr.sin_port = htons(1234);
	connect(clntSock, (sockaddr *)&clntAddr, sizeof(clntAddr));
	
	//循环接收数据，直到文件传输完毕
	//文件缓冲区
	char buffer[BUFSIZE] = {0};
	int nCount = 0;
	while( (nCount = recv(clntSock, buffer, BUFSIZE, 0)) > 0)
		fwrite(buffer, 1, nCount, fp);
	
	printf("File transfer success!\n");

	//文件接收完毕后直接关闭套接字，无需调用shutdown().
	fclose(fp);
	//关闭套接字
	closesocket(clntSock);
	
	//终止使用 DLL
	WSACleanup();

	system("pause");
	return 0;
}