使用zlib进行压缩，解压缩

头文件：

#include "zlib.h"

编译：

需要加上 -lz

解压缩：

#define CHUNK 100000

int decodeZip(char *source,int len,char **dest)
{
    int ret;
    unsigned have;
    z_stream strm;
    unsigned char out[CHUNK];
    int totalsize = 0;

    /* allocate inflate state */
    strm.zalloc = Z_NULL;
    strm.zfree = Z_NULL;
    strm.opaque = Z_NULL;
    strm.avail_in = 0;
    strm.next_in = Z_NULL;

    ret = inflateInit2(&strm, 31);

    if (ret != Z_OK)
        return ret;

    strm.avail_in = len;
    strm.next_in = (unsigned char*)source;

    /* run inflate() on input until output buffer not full */
    do {
        strm.avail_out = CHUNK;
        strm.next_out = out;
        ret = inflate(&strm, Z_NO_FLUSH);
        switch (ret)
        {
            case Z_NEED_DICT:
                ret = Z_DATA_ERROR; /* and fall through */
            case Z_DATA_ERROR:
            case Z_MEM_ERROR:
                inflateEnd(&strm);
            return ret;
        }

        have = CHUNK - strm.avail_out;
        totalsize += have;
        *dest = (char*)realloc(*dest,totalsize);
        memcpy(*dest + totalsize - have,out,have);
    } while (strm.avail_out == 0);

    /* clean up and return */
    inflateEnd(&strm);
    return ret == Z_STREAM_END ? Z_OK : Z_DATA_ERROR;
}

压缩：

#define MaxLen 10000000

/**
 * 对内容进行压缩和编码工作
 */
void encodeZip(const string &buffer, string& zipBuf, int& zipLen)
{
    unsigned char _zipSrc[MaxLen];
    unsigned char _zipDst[MaxLen];
    unsigned char 
_scBuffer[MaxLen];

   //先对原始内容进行压缩工作
    unsigned int tmpLen = buffer.length();
    memcpy(_zipSrc, buffer.c_str(), tmpLen);
    z_stream c_stream;
    c_stream.zalloc = (alloc_func)0;
    c_stream.zfree = (free_func)0;
    c_stream.opaque = (voidpf)0;
    c_stream.next_in  = (Bytef*)_zipSrc;
    c_stream.avail_in = tmpLen;
    c_stream.next_out = (Bytef*)_zipDst;
    c_stream.avail_out = (unsigned int)MaxLen;
    int ret = deflateInit2(&c_stream, Z_DEFAULT_COMPRESSION,Z_DEFLATED, 31,8, Z_DEFAULT_STRATEGY);
    if(ret != Z_OK)
    {
        cout <<"|"<<"deflateInit2 error "<<endl;
        return;
    }
    ret = deflate(&c_stream, Z_FINISH);
    if (ret != Z_STREAM_END)
    {
        deflateEnd(&c_stream);
        cout <<"|"<<"ret != Z_STREAM_END  err="<< ret <<endl;
        return;
    }

    zipLen = c_stream.total_out;
    ret = deflateEnd(&c_stream);
    if (ret != Z_OK)
    {
        cout <<"|"<<"deflateEnd error "<<endl;
        return;
    }
    //压缩完毕进行返回包组织
    memcpy(_scBuffer, _zipDst, zipLen);
    zipBuf = string(_scBuffer, zipLen);
    return;
}