C++zlib库实现的GZIP压缩解压缩工具类【多图警告^

前几天和服务端同事联调TCP传输压缩后的Json串，遇到了 GZIP压缩问题。
需要把原来使用的的压缩算法和后端统一，现在来总结一下。

【注意】这里就以Windows的Debug环境为例，Release版也是一样，只需更改配置编译就好。
代码演示中不未涉及文件序列化问题。文件（文件夹）压缩问题，可以参考zip压缩文章Zip压缩解压缩

1.下载zlib源码及工程文件：
https://www.zlib.net/

2.拿到源码包解压看看

3.打开目录zlib-1.2.11\contrib\vstudio\vc12下的解决方案：

一堆错误，编译失败：

解决方案：https://www.cnblogs.com/lzhu/p/9602674.html

我在示例中使用的VS2013编译的VC12的示例解决方案，报错。得把这六个工程都修复下：

编译成功：

4.编译成功，得到库文件：
打开工程目录，从x86\ZlibDllDebug下拿到库文件zlibwapi.lib和zlibwapi.dll，再从压缩包根目录zlib-1.2.11\下拿到zlib.h、zconf.h、zutil.h三个头文件

5.新建测试工程，并添加zlib目录，把拿到的lib文件以及三个头文件文件放进去，并把dll文件放到debug目录下。

6.demo工程属性-链接器-常规-附加依赖项-…/zlib/debug/zlibwapi.lib;

7.添加工具类CGZipAssistant到工程里面：

/*
GZipAssisant.h
*/
#pragma once
class GZipAssistant
{public:GZipAssistant();~GZipAssistant();public:int Compress(const char *src, int srcLen, char *dest, int destLen);int Decompress(const char *src, int srcLen, const char *dst, int dstLen);static GZipAssistant* GetInstance(){static GZipAssistant ins;return &ins;}
};GZipAssistant* GetGZipAssistant();

/*
GZipAssisant.cpp
*/
#include "stdafx.h"
#include "../zlib/zlib.h"
#include "GZipAssisant.h"#ifdef _DEBUG
#define new DEBUG_NEW
#endifGZipAssistant::GZipAssistant()
{}GZipAssistant::~GZipAssistant()
{}int GZipAssistant::Compress(const char *src, int srcLen, char *dest, int destLen)
{z_stream c_stream;int err = 0;int windowBits = 15;int GZIP_ENCODING = 16;if (src && srcLen > 0){c_stream.zalloc = (alloc_func)0;c_stream.zfree = (free_func)0;c_stream.opaque = (voidpf)0;if (deflateInit2(&c_stream, Z_DEFAULT_COMPRESSION, Z_DEFLATED,windowBits | GZIP_ENCODING, 8, Z_DEFAULT_STRATEGY) != Z_OK) return -1;c_stream.next_in = (Bytef *)src;c_stream.avail_in = srcLen;c_stream.next_out = (Bytef *)dest;c_stream.avail_out = destLen;while (c_stream.avail_in != 0 && c_stream.total_out < destLen){if (deflate(&c_stream, Z_NO_FLUSH) != Z_OK) return -1;}if (c_stream.avail_in != 0) return c_stream.avail_in;for (;;) {if ((err = deflate(&c_stream, Z_FINISH)) == Z_STREAM_END) break;if (err != Z_OK) return -1;}if (deflateEnd(&c_stream) != Z_OK) return -1;return c_stream.total_out;}return -1;
}int GZipAssistant::Decompress(const char *src, int srcLen, const char *dst, int dstLen) {z_stream strm;strm.zalloc = NULL;strm.zfree = NULL;strm.opaque = NULL;strm.avail_in = srcLen;strm.avail_out = dstLen;strm.next_in = (Bytef *)src;strm.next_out = (Bytef *)dst;int err = -1, ret = -1;err = inflateInit2(&strm, MAX_WBITS + 16);if (err == Z_OK) {err = inflate(&strm, Z_FINISH);if (err == Z_STREAM_END) {ret = strm.total_out;}else {inflateEnd(&strm);return err;}}else {inflateEnd(&strm);return err;}inflateEnd(&strm);return err;
}GZipAssistant* GetGZipAssistant()
{return GZipAssistant::GetInstance();
}

8.调用测试：


void CDemoDlg::OnBnClickedButtonGogogo()
{//压缩：const char* pSrc = "12312312313萨达萨达木alkjslngadaldn扩锁军，#￥@……@！#多绿蓑女所军副盘";int nLenSrc = strlen(pSrc);int nLenCompress = nLenSrc * 2;char* pCompressed = new char[nLenCompress];memset(pCompressed, 0, nLenCompress);int nLencompressed = GetGZipAssistant()->Compress(pSrc, nLenSrc, pCompressed, nLenCompress);if (nLencompressed <= 0){MessageBox("Compress Failed");}//解压缩：char* pDecompressed = new char[nLenSrc * 2];memset(pDecompressed, 0, nLenSrc * 2);int ret = GetGZipAssistant()->Decompress(pCompressed, nLencompressed, pDecompressed, nLenSrc * 2);CString str = pDecompressed;MessageBox(str);delete[] pCompressed;delete[] pDecompressed;
}

测试成功，Release版本的一样的套路，改改配置编译即可，亲测可行。

参考文章：
https://blog.csdn.net/moxiaomomo/article/details/52385837
https://www.cnblogs.com/lzhu/p/9602674.html

C++zlib库实现的GZIP压缩解压缩工具类【多图警告^_^】

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