java lzma 解压例子_LZMA压缩解压

#include “stdafx.h”#include#include#include#include#include

#define LZMA_API_STATIC#include”lzma.h”

#define LZMA_PRESET_VAL 0

staticuint32_t

get_preset()

{return LZMA_PRESET_VAL |LZMA_PRESET_EXTREME;

}static boolget_error(lzma_ret ret)

{//Return successfully if the initialization went fine.

if (ret == LZMA_OK |LZMA_STREAM_END)return true;//Something went wrong. The possible errors are documented in//lzma/container.h (src/liblzma/api/lzma/container.h in the source//package or e.g. /usr/include/lzma/container.h depending on the//install prefix).

const char *msg;switch(ret) {caseLZMA_MEM_ERROR:

msg= “Memory allocation failed”;break;caseLZMA_OPTIONS_ERROR:

msg= “Specified preset is not supported”;break;caseLZMA_UNSUPPORTED_CHECK:

msg= “Specified integrity check is not supported”;break;default://This is most likely LZMA_PROG_ERROR indicating a bug in//this program or in liblzma. It is inconvenient to have a//separate error message for errors that should be impossible//to occur, but knowing the error code is important for//debugging. That’s why it is good to print the error code//at least when there is no good error message to show.

msg = “Unknown error, possibly a bug”;break;

}

fprintf(stderr,”Error initializing the encoder: %s (error code %u)\n”,

msg, ret);return false;

}static boolinit_encoder(lzma_stream*strm, uint32_t preset)

{//Initialize the encoder using a preset. Set the integrity to check//to CRC64, which is the default in the xz command line tool. If//the .xz file needs to be decompressed with XZ Embedded, use//LZMA_CHECK_CRC32 instead.

lzma_ret ret =lzma_easy_encoder(strm, preset, LZMA_CHECK_CRC64);returnget_error(ret);

}static boolinit_decoder(lzma_stream*strm)

{//Initialize a .xz decoder. The decoder supports a memory usage limit//and a set of flags.//

//The memory usage of the decompressor depends on the settings used//to compress a .xz file. It can vary from less than a megabyte to//a few gigabytes, but in practice (at least for now) it rarely//exceeds 65 MiB because that’s how much memory is required to//decompress files created with “xz -9”. Settings requiring more//memory take extra effort to use and don’t (at least for now)//provide significantly better compression in most cases.//

//Memory usage limit is useful if it is important that the//decompressor won’t consume gigabytes of memory. The need//for limiting depends on the application. In this example,//no memory usage limiting is used. This is done by setting//the limit to UINT64_MAX.//

//The .xz format allows concatenating compressed files as is://

//echo foo | xz > foobar.xz//echo bar | xz >> foobar.xz//

//When decompressing normal standalone .xz files, LZMA_CONCATENATED//should always be used to support decompression of concatenated//.xz files. If LZMA_CONCATENATED isn’t used, the decoder will stop//after the first .xz stream. This can be useful when .xz data has//been embedded inside another file format.//

//Flags other than LZMA_CONCATENATED are supported too, and can//be combined with bitwise-or. See lzma/container.h//(src/liblzma/api/lzma/container.h in the source package or e.g.///usr/include/lzma/container.h depending on the install prefix)//for details.

lzma_ret ret =lzma_stream_decoder(

strm, UINT64_MAX, LZMA_CONCATENATED);returnget_error(ret);

}static booldo_lzma_code(lzma_stream*strm, const unsigned char *in_buff,const int in_size, unsigned char *out_buff, int &out_size)

{

lzma_action action=LZMA_FINISH;

uint8_t outbuf[BUFSIZ];

strm->next_out =outbuf;

strm->avail_out = sizeof(outbuf);

strm->next_in =in_buff;

strm->avail_in =in_size;

lzma_ret ret=lzma_code(strm, action);

out_size= sizeof(outbuf) – strm->avail_out;

memcpy(out_buff,outbuf,out_size);returnget_error(ret);

}voidwang_compress(const unsigned char *in_buff,const int in_size, unsigned char *out_buff, int &out_size)

{

uint32_t preset=get_preset();

lzma_stream strm=LZMA_STREAM_INIT;bool success = init_encoder(&strm, preset);if(success)

{

success= do_lzma_code(&strm, in_buff,in_size,out_buff, out_size);

}

lzma_end(&strm);

}voidwang_decompress(const unsigned char *in_buff,const int in_size, unsigned char *out_buff, int &out_size)

{

lzma_stream strm=LZMA_STREAM_INIT;bool success = true;if (!init_decoder(&strm)) {//Decoder initialization failed. There’s no point//to retry it so we need to exit.

success = false;

}

success&= do_lzma_code(&strm,in_buff,in_size,out_buff,out_size);

lzma_end(&strm);

}int _tmain(int argc, _TCHAR*argv[])

{const unsigned char const_string_value[] = “wjfsjfsjfojsofjsojrhghfgehoiheighehgehgieghhgohg osjfi`, sk;f;’l”;

std::cout<

std::cout<

unsignedchar buff[1024] = {0};int size = 0;

wang_compress(const_string_value,const_string_size,buff,size);

std::cout<

unsignedchar out_string_value[1024]={0};int out_string_size = 0;

wang_decompress(buff,size,out_string_value,out_string_size);

assert(out_string_size==const_string_size);

std::cout<

std::cout<

std::cin>>out_string_size;

}