场景：
1. zlib库跨平台，Windows和MacOSX都可以使用，还支持64位编译，轻量级，没有不用的道理。
2. 处理.zip,apk,docx文件时，因为这类文件都是zip格式，使用zlib能方便提取压缩文件里的数据。
方法：
1. 除了要使用zlib库本身，还需要使用zlib里的contrib目录minizip部分头文件和.c文件。
zlib-1.2.5/src/contrib/minizip/unzip.hunzip.c,ioapi.c,ioapi.h (windows还需要 iowin32.h, iowind32.c)
2. 例子，读取压缩文件里的某个文件到内存std::string, 基本原理就是打开zip文件，定位需要读取的文件，之后读取这个文件，关闭zip文件。
以下代码只支持Mac.
#include "zip/zip_util.h"#include <iostream>#include <string>#include <algorithm>#include <stdlib.h>#include <zlib.h>#include "zip/unzip.h"using namespace std;#define WRITEBUFFERSIZE (1242880) // 5Mb bufferstring ZipUtil::ReadZipFile(string zipFile, string fileInZip) { int err = UNZ_OK; // error status uInt size_buf = WRITEBUFFERSIZE; // byte size of buffer to store raw csv data void* buf; // the buffer string sout; // output strings char filename_inzip[256]; // for unzGetCurrentFileInfo unz_file_info file_info; // for unzGetCurrentFileInfo unzFile uf = unzOpen64(zipFile.c_str()); // open zipfile stream if (uf==NULL) { cerr << "Cannot open " << zipFile << endl; return sout; } // file is open if ( unzLocateFile(uf,fileInZip.c_str(),1) ) { // try to locate file inside zip // second argument of unzLocateFile: 1 = case sensitive, 0 = case-insensitive cerr << "File " << fileInZip << " not found in " << zipFile << endl; return sout; } // file inside zip found if (unzGetCurrentFileInfo(uf,&file_info,filename_inzip,sizeof(filename_inzip),NULL,0,NULL,0)) { cerr << "Error " << err << " with zipfile " << zipFile << " in unzGetCurrentFileInfo." << endl; return sout; } // obtained the necessary details about file inside zip buf = (void*)malloc(size_buf); // setup buffer if (buf==NULL) { cerr << "Error allocating memory for read buffer" << endl; return sout; } // buffer ready err = unzOpenCurrentFilePassword(uf,NULL); // Open the file inside the zip (password = NULL) if (err!=UNZ_OK) { cerr << "Error " << err << " with zipfile " << zipFile << " in unzOpenCurrentFilePassword." << endl; return sout; } // file inside the zip is open // Copy contents of the file inside the zip to the buffer cout << "Extracting: " << filename_inzip << " from " << zipFile << endl; do { err = unzReadCurrentFile(uf,buf,size_buf); if (err<0) { cerr << "Error " << err << " with zipfile " << zipFile << " in unzReadCurrentFile" << endl; sout = ""; // empty output string break; } // copy the buffer to a string if (err>0) for (int i = 0; i < (int) err; i++) sout.push_back( *(((char*)buf)+i) ); } while (err>0); err = unzCloseCurrentFile (uf); // close the zipfile if (err!=UNZ_OK) { cerr << "Error " << err << " with zipfile " << zipFile << " in unzCloseCurrentFile" << endl; sout = ""; // empty output string } unzClose(uf); free(buf); // free up buffer memory return sout;}
Windows的路径需要Unicode才能支持中文路径,所以用以下的UnzOpen64实现:
unzFile ZipUtil::UnzOpen64(const char* path){zlib_filefunc64_def ffunc; fill_win32_filefunc64W(&ffunc); wchar_t* temp_path = Utf82Unicode(path); unzFile zf = unzOpen2_64(temp_path,&ffunc);return zf;}