CGZip，一个C++ gzip方法封装

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描述

本文档介绍CGZip，一个C++类，用于封装zlib库中的gzip方法。该类的目的是提供一个简单的类，用于压缩和解压缩缓冲区。

该类的主要特性是：

• 将LPCTSTR压缩和解压缩到文件
• 将内存缓冲区压缩和解压缩到文件
• 非MFC
• 隐藏zlib，因此您无需分发zlib头文件
• 符合UNICODE标准

示例

在示例中，我们假设以下代码片段位于顶部

// CGZip is in the zlib namespace
using namespace zlib;
CGZip gzip;

压缩内存缓冲区或字符串

首先，让我们打开一个文件进行写入

if(!gzip.Open(_T("myFile.gz"), CGZip::ArchiveModeWrite)))
{
        // the file could not be opened...
}

如您所见，Open在成功时返回true，否则返回false。 几乎所有方法都具有这种行为。

现在我们可以将数据和字符串发送到文件

字符串

LPCTSTR szString = _T("This is a test string\n");
// writing string
gzip.WriteString(szString);

缓冲区 (Buffers)

void* pBuffer; // a memory buffer
int len;       // size in bytes of the memory buffer
// writing buffer
gzip.WriteBuffer(pBuffer,len);

完成时，您必须关闭文件

gzip.Close();

请注意，如果gzip超出作用域，它将自动关闭。

解压缩缓冲区或字符串

读取行为与写入行为非常相似。 首先，打开一个文件进行读取

if(!gzip.Open(_T("myFile.gz"), CGZip::ArchiveModeRead)))
{
        // the file could not be opened...
}

现在，您可以读取固定长度的缓冲区或整个文件

整个文件

void* pBuffer=NULL;
int len=0;
// reads and unzip the hole file, len contains the resulting size of pBuffer
gzip.ReadBuffer(&pBuffer,&len);
// pBuffer now contains len read bytes
...
// don't forget to delete pBuffer
if (pBuffer)
   delete[] pBuffer;

固定长度的缓冲区

  int len;
char* pBuffer[len];
// reads and unzip the hole file, len contains the resulting size of pBuffer
gzip.ReadBufferSize(pBuffer,len);

类参考

详细的类参考资料以压缩HTML格式提供（由Doxygen生成）。

GZip 许可

这段代码完全且绝对可以用于商业和非商业用途。 但是，它使用zlib，因此您在使用它之前应检查zlib许可。 它包含在源代码中，但这里也提供：

//zlib.h -- interface of the 'zlib' general purpose compression library
//version 1.1.4, March 11th, 2002

//Copyright (C) 1995-2002 Jean-loup Gailly and Mark Adler

//This software is provided 'as-is', without any express or implied
//warranty.  In no event will the authors be held liable for any damages
//arising from the use of this software.

//Permission is granted to anyone to use this software for any purpose,
//including commercial applications, and to alter it and redistribute it
//freely, subject to the following restrictions:

//1. The origin of this software must not be misrepresented; you must not
//   claim that you wrote the original software. If you use this software
//   in a product, an acknowledgment in the product documentation would be
//   appreciated but is not required.
//2. Altered source versions must be plainly marked as such, and must not be
//   misrepresented as being the original software.
//3. This notice may not be removed or altered from any source distribution.

//Jean-loup Gailly        Mark Adler
//jloup@gzip.org          madler@alumni.caltech.edu


//The data format used by the zlib library is described by RFCs (Request for
//Comments) 1950 to 1952 in the files ftp://ds.internic.net/rfc/rfc1950.txt
//(zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).