Zip压缩文件与解压（MFC文件操作四）

一、压缩文件

 

我们的程序要用到了zip压缩，就需要自己将几个zip相关文件加入到工程中

 

zlib.h  zconf.h  zlib.lib  这些可以自己上网下载  http://d.download.csdn.net/down/2344459/mryeze

 

在程序中要将 两个.h文件 add to project。然后声明引入lib

#include "zlib.h"//压缩文件相关
#include "zconf.h"
#pragma comment(lib,"zlib.lib")

 

这些工作只是为了使程序中的关键函数compress 能够使用

之后就写我们的代码了，源代码是网上找的，自己在做的时候，对其做了一点修改，使其能直接运行。

 

HANDLE hFile, hFileToWrite;

CString strFilePath = "C:/aaa.txt"; //要压缩的文件的路径
                                                 // 下载的源代码中后缀名为rar,经测试无法打开

//打开要进行压缩的文件
hFile = CreateFile(strFilePath, // file name
    GENERIC_READ, // open for reading
    FILE_SHARE_READ, // share for reading
    NULL, // no security
    OPEN_EXISTING, // existing file only
    FILE_ATTRIBUTE_NORMAL, // normal file
    NULL
    ); // no attr. template
if (hFile == INVALID_HANDLE_VALUE)
{
    AfxMessageBox("Could not open file to read"); // process error
    return;
}

HANDLE hMapFile, hMapFileToWrite;
//创建一个文件映射
hMapFile = CreateFileMapping(hFile, // Current file handle.
    NULL, // Default security.
    PAGE_READONLY, // Read/write permission.
    0, // Max. object size.
    0, // Size of hFile.
    "ZipTestMappingObjectForRead"
    ); // Name of mapping object.
if (hMapFile == NULL)
{
    AfxMessageBox("Could not create file mapping object");
    return;
}


LPVOID lpMapAddress, lpMapAddressToWrite;
//创建一个文件映射的视图用来作为source
lpMapAddress = MapViewOfFile(hMapFile, // Handle to mapping object.
    FILE_MAP_READ, // Read/write permission
    0, // Max. object size.
    0, // Size of hFile.
    0); // Map entire file.
if (lpMapAddress == NULL)
{
    AfxMessageBox("Could not map view of file");
    return;
}


DWORD dwFileLength,dwFileLengthToWrite;
dwFileLength = GetFileSize(hFile, NULL);    //获取文件的大小

/   m_dwSourceFileLength = dwFileLength;

//因为压缩函数的输出缓冲必须比输入大0.1% + 12 然后一个DWORD 用来保存压缩前的大小，
    // 解压缩的时候用，当然还可以保存更多的信息，这里用不到
dwFileLengthToWrite = (double)dwFileLength*1.001 + 12 +sizeof(DWORD);


//以下是创建一个文件，用来保存压缩后的文件
hFileToWrite = CreateFile("C:/demoFile.txt", // demoFile.rar
    GENERIC_WRITE|GENERIC_READ, // open for writing
    0, // do not share
    NULL, // no security
    CREATE_ALWAYS, // overwrite existing
    FILE_ATTRIBUTE_NORMAL , // normal file
    NULL); // no attr. template
if (hFileToWrite == INVALID_HANDLE_VALUE)
{
    AfxMessageBox("Could not open file to write"); // process error
    return;
}

//为输出文件  创建一个文件映射
hMapFileToWrite = CreateFileMapping(hFileToWrite, // Current file handle.
    NULL, // Default security.
    PAGE_READWRITE, // Read/write permission.
    0, // Max. object size.
    dwFileLengthToWrite, // Size of hFile.
    "ZipTestMappingObjectForWrite"); // Name of mapping object.
if (hMapFileToWrite == NULL)
{
    AfxMessageBox("Could not create file mapping object for write");
    return;
}

//为输出文件 创建一个文件映射视图
lpMapAddressToWrite = MapViewOfFile(hMapFileToWrite, //Handle to mapping
    FILE_MAP_WRITE, // Read/write permission 0, // Max. object size.
    0, // Size of hFile.
    0,
    0
    ); // Map entire file.
if (lpMapAddressToWrite == NULL)
{
    AfxMessageBox("Could not map view of file");
    return;
}

//这里是将压缩前的大小保存在文件的第一个DWORD 里面
LPVOID pBuf = lpMapAddressToWrite;
(*(DWORD*)pBuf) = dwFileLength;
pBuf = (DWORD*)pBuf + 1;

//这里就是最重要的，zlib 里面提供的一个方法，将源缓存的数据压缩至目的缓存
//原形如下：
//int compress (Bytef *dest, uLongf *destLen, const Bytef*source, uLong sourceLen);
//参数destLen 返回实际压缩后的文件大小。
compress((Bytef*)pBuf,&dwFileLengthToWrite, (Bytef*)lpMapAddress, dwFileLength);

UnmapViewOfFile(lpMapAddress);
CloseHandle(hMapFile);
CloseHandle(hFile);
UnmapViewOfFile(lpMapAddressToWrite);
CloseHandle(hMapFileToWrite);

//这里将文件大小重新设置一下
SetFilePointer(hFileToWrite,dwFileLengthToWrite + sizeof(DWORD) ,NULL,FILE_BEGIN);
SetEndOfFile(hFileToWrite);
CloseHandle(hFileToWrite);

 

运行程序后，将aaa.txt文件压缩成功了。

 

 

 

二、解压文件

 

解压文件的思路和压缩差不多，其中的区别就是

1. 输出文件缓冲区大小的设定

zip为：

//因为压缩函数的输出缓冲必须比输入大0.1% + 12 然后一个DWORD 用来保存压缩前的大小，
// 解压缩的时候用，当然还可以保存更多的信息，这里用不到
dwFileLengthToWrite = (double)dwFileLength*1.001 + 12 +sizeof(DWORD);

 

upzip为：

dwFileLengthToWrite = (*(DWORD*)lpMapAddress);

 

2 compress 与 uncompress函数

这个是必须的了！

compress((Bytef*)pBuf,&dwFileLengthToWrite, (Bytef*)lpMapAddress, dwFileLength);

 

uncompress((Bytef*)pBuf,&dwFileLengthToWrite, (Bytef*)pSourceBuf, dwFileLength);

 

还是提供源代码

HANDLE hFile, hFileToWrite;
CString strFilePath="C:/demoFile.txt";
//打开要进行解压缩的文件
hFile = CreateFile(strFilePath, // file name
    GENERIC_READ, // open for reading
    FILE_SHARE_READ, // share for reading
    NULL, // no security
    OPEN_EXISTING, // existing file only
    FILE_ATTRIBUTE_NORMAL, // normal file
    NULL
    ); // no attr. template
if (hFile == INVALID_HANDLE_VALUE)
{
    AfxMessageBox("Could not open file to read"); // process error
    return;
}
HANDLE hMapFile, hMapFileToWrite;
//创建一个文件映射
hMapFile = CreateFileMapping(hFile, // Current file handle.
    NULL, // Default security.
    PAGE_READONLY, // Read/write permission.
    0, // Max. object size.
    0, // Size of hFile.
    "ZipTestMappingObjectForRead"); // Name of mapping object.
if (hMapFile == NULL)
{
    AfxMessageBox("Could not create file mapping object");
    return;
}
LPVOID lpMapAddress, lpMapAddressToWrite;
//创建一个文件映射的视图用来作为source
lpMapAddress = MapViewOfFile(hMapFile, // Handle to mapping
    FILE_MAP_READ, // Read/write permission
    0, // Max. object size.
    0, // Size of hFile.
    0); // Map entire file.
if (lpMapAddress == NULL)
{
    AfxMessageBox("Could not map view of file");
    return;
}
DWORD dwFileLength,dwFileLengthToWrite;
dwFileLength = GetFileSize(hFile, NULL) - sizeof(DWORD);
//因为压缩函数的输出缓冲必须比输入大0.1% + 12 然后一个DWORD 用来保存压缩前的大小，
    // 解压缩的时候用，当然还可以保存更多的信息，这里用不到
    // dwFileLengthToWrite = (double)dwFileLength*1.001 + 12 +sizeof(DWORD);
    dwFileLengthToWrite = (*(DWORD*)lpMapAddress);
LPVOID pSourceBuf = lpMapAddress;
pSourceBuf = (DWORD*)pSourceBuf + 1;
//以下是创建一个文件，用来保存压缩后的文件
hFileToWrite = CreateFile("C:/UnZipFile.txt", // create demo.gz
    GENERIC_WRITE|GENERIC_READ, // open for writing
    0, // do not share
    NULL, // no security
    CREATE_ALWAYS, // overwrite existing
    FILE_ATTRIBUTE_NORMAL , // normal file
    NULL
    ); // no attr. template
if (hFileToWrite == INVALID_HANDLE_VALUE)
{
    AfxMessageBox("Could not open file to write"); //process error
    return;
}
hMapFileToWrite = CreateFileMapping(hFileToWrite, // Currentfile handle.
    NULL, // Default security.
    PAGE_READWRITE, // Read/write permission.
    0, // Max. object size.
    dwFileLengthToWrite, // Size of hFile.
    "ZipTestMappingObjectForWrite"); // Name of mapping object.
if (hMapFileToWrite == NULL)
{
    AfxMessageBox("Could not create file mapping object for write");
    return;
}
lpMapAddressToWrite = MapViewOfFile(hMapFileToWrite, //Handle to mapping object.
    FILE_MAP_WRITE, // Read/write permission
    0, // Max. object size.
    0, // Size of hFile.
    0
    ); // Map entire file.
if (lpMapAddressToWrite == NULL)
{
    AfxMessageBox("Could not map view of file");
    return;
}
//这里是将压缩前的大小保存在文件的第一个DWORD 里面
LPVOID pBuf = lpMapAddressToWrite;
//这里就是最重要的，zlib 里面提供的一个方法，将源缓存的数据压缩至目的缓存
//原形如下：
//int compress (Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen);
//参数destLen 返回实际压缩后的文件大小。
uncompress((Bytef*)pBuf,&dwFileLengthToWrite, (Bytef*)pSourceBuf, dwFileLength);
UnmapViewOfFile(lpMapAddress);
CloseHandle(hMapFile);
CloseHandle(hFile);
UnmapViewOfFile(lpMapAddressToWrite);
CloseHandle(hMapFileToWrite);
//这里将文件大小重新设置一下
SetFilePointer(hFileToWrite,dwFileLengthToWrite,NULL,FILE_BEGIN);
SetEndOfFile(hFileToWrite);
CloseHandle(hFileToWrite);

 

运行效果如下：