使用Zlib库进行多文件或者多文件夹的压缩解压缩

zlib库可在git上自己clone下来然后使用cmake工具生成解决方案，编译、生成zlib二进制文件。然后将zlib库引入项目：

//zlib库支持
#include "../zlib/include/zlib.h"
#ifdef _DEBUG
#pragma comment(lib, "../zlib/lib/zlibd.lib")
#else
#pragma comment(lib, "../zlib/lib/zlib.lib")
#endif

首先我们定义一个文件结构：

typedef struct tagZipperFileInfo
{
	char m_szLocalPath[MAX_PATH];
	char m_szRootPath[MAX_PATH];
	char m_szFileName[MAX_PATH];
	size_t m_FileSize;
}ZipperFileInfo;

然后我们来处理文件的压缩，包括遍历所选的目录下的所有文件。

void OperateFolder(std::string& strFolder, std::string& strRoot, std::vector& vecZipperFiles)
{
	std::string searchPath = strFolder + "\\*";
	WIN32_FIND_DATAA findData;
	HANDLE hFind = FindFirstFileA(searchPath.c_str(), &findData);
	if (hFind == INVALID_HANDLE_VALUE) {
		//error
		return;
	}
	do {
		if (findData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
			if (strcmp(findData.cFileName, ".") != 0 && strcmp(findData.cFileName, "..") != 0) 
			{
				std::string subFolderPath = strFolder + "\\" + findData.cFileName;
				OperateFolder(subFolderPath, strRoot, vecZipperFiles);
			}
		}
		else {
			std::string strLocalPath = strFolder + "\\" + findData.cFileName;
			std::string strFileRootPath = strFolder;
			std::string strFileName = findData.cFileName;

			//需要根据strRoot分割出来需要压缩文件的相对路径名
			std::string strTempPath;
			size_t start = strFileRootPath.find(strRoot);
			if (start == std::string::npos)
				strTempPath = strFileRootPath; // 如果找不到根路径，则返回完整路径
			else
			{
				if (strFileRootPath == strRoot)
					strTempPath = strFileRootPath.substr(start + strRoot.length());
				else
					strTempPath = strFileRootPath.substr(start + strRoot.length() + 1);
			}

			ZipperFileInfo zipperFile;
			memcpy(zipperFile.m_szRootPath, strTempPath.c_str(), MAX_PATH);
			memcpy(zipperFile.m_szLocalPath, strLocalPath.c_str(), MAX_PATH);
			memcpy(zipperFile.m_szFileName, strFileName.c_str(), MAX_PATH);

			//计算文件大小
			std::ifstream in(strLocalPath, std::ios::binary | std::ios::ate);
			size_t fileSize = in.tellg();
			in.seekg(0);
			in.close();
			zipperFile.m_FileSize = fileSize;

			vecZipperFiles.push_back(zipperFile);
		}
	} while (FindNextFileA(hFind, &findData) != 0);
	FindClose(hFind);
}

/*
*	strFolder	需要被压缩的文件夹
*	strOut		保存的文件
*/
void CompressFolder(std::string& strFolder, std::string& strOut)
{
	//创建压缩的目标文件
	std::ofstream dest(strOut, std::ios::binary | std::ios::trunc);
	if (!dest.is_open()) {
		//error
		return;
	}
	dest.close();

	std::vector vecZipperFiles;
	//遍历文件夹下的所有文件
	OperateFolder(strFolder, strFolder, vecZipperFiles);

	//压缩文件
	gzFile gzOut = gzopen(strOut.c_str(), "wb");
	CompressFiles(vecZipperFiles, gzOut);
	gzclose(gzOut);
}

然后进行文件压缩：

void CompressFiles(std::vector& vecZipperFiles, gzFile& gzOut)
{
	int nFileCount = vecZipperFiles.size();
	gzwrite(gzOut, reinterpret_cast(&nFileCount), 4);
	gzwrite(gzOut, reinterpret_cast(vecZipperFiles.data()), vecZipperFiles.size() * sizeof(ZipperFileInfo));

	//再往压缩文件中写入需要压缩为文件内容
	for (int i = 0; i < vecZipperFiles.size(); i++)
	{
		std::string strLocalPath = vecZipperFiles[i].m_szLocalPath;
		std::ifstream infile(strLocalPath, std::ios::binary);
		char buffer[4096];
		while (infile)
		{
			infile.read(buffer, sizeof(buffer));
			auto bytes = infile.gcount();
			if (bytes > 0)
			{
				//写入目标压缩文件
				gzwrite(gzOut, buffer, bytes);
			}
		}
		infile.close();
	}
}

以上即为文件压缩。下边我们看看对压缩的文件进行解压处理：

/*递归生成压缩文件中的目录结构：
*	strRoot	解压缩的目标目录
*	strDir	压缩文件的相对路径
*/
void CreateFolder(std::string& strRoot, std::string& strDir)
{
	size_t szPos = strDir.find_first_of("\\");
	if (szPos != std::string::npos)
	{
		std::string strName = strDir.substr(0, szPos);
		std::string strPath = strRoot + "\\" + strName;
		CreateDirectoryA(strPath.c_str(), NULL);

		std::string strSubName = strDir.substr(szPos + 1);
		std::string strTempRoot = strRoot + "\\" + strName;
		CreateFolder(strTempRoot, strSubName);
	}
	else
	{
		std::string strPath = strRoot + "\\" + strDir;
		CreateDirectoryA(strPath.c_str(), NULL);
	}
}

//strFilePath 压缩文件路径
void DecompressFiles(std::string& strFilePath)
{
	gzFile gzin = gzopen(strFilePath.c_str(), "rb");
	if (!gzin) return; //open error

	int nFileCount = 0;
	gzread(gzin, &nFileCount, 4); //读取压缩的文件数量

	// 读取文件列表信息
	std::vector vecZipperFiles;
	ZipperFileInfo zipperFile;
	for (int i = 0; i < nFileCount; i++)
	{
		if (gzread(gzin, &zipperFile, sizeof(ZipperFileInfo)) == sizeof(ZipperFileInfo))
			vecZipperFiles.push_back(zipperFile);
	}

	SStringW sstrAppPath = CGlobalUnits::GetInstance()->m_sstrAppPath;
	std::string strAppPath = S_CW2A(sstrAppPath);

	//先创建个输出目录
	size_t szPos = strFilePath.find_last_of("\\");
	if (szPos != std::string::npos)
	{
		std::string strTmp = strFilePath.substr(szPos + 1);
		//分解出name
		size_t szName = strTmp.find_last_of(".");
		if (szName != std::string::npos)
		{
			std::string strName = strTmp.substr(0, szName);
			strAppPath += strName;
		}
	}
	CreateDirectoryA(strAppPath.c_str(), NULL);

	//解压文件
	for (int i = 0; i < vecZipperFiles.size(); i++)
	{
		ZipperFileInfo& info = vecZipperFiles[i];
		std::string strRoot = info.m_szRootPath;

		std::string strPath;
		if (strRoot == "")  //根目录下
			strPath = strAppPath + "\\" + info.m_szFileName;
		else
		{
			CreateFolder(strAppPath, strRoot);
			strPath = strAppPath + "\\" + strRoot + "\\" + info.m_szFileName;
		}
		std::ofstream outFile(strPath, std::ios::binary);
		if (!outFile) continue;  //error 
		char buffer[4096];
		size_t fileSize = info.m_FileSize;
		while (fileSize > 0)
		{
			size_t bytesToRead = std::min(static_cast(4096), fileSize);
			int bytesRead = gzread(gzin, buffer, bytesToRead);
			if (bytesRead <= 0) break; //read error
			outFile.write(buffer, bytesRead);
			fileSize -= bytesRead;
		}
		outFile.close();
	}

	gzclose(gzin);
}

以上即为使用zlib库进行文件的压缩解压缩相关的代码。但是以上处理非标准的压缩解压缩，压缩的文件不能被市面通用的zip软件解压也不能解压市面通用软件压缩的zip包。