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https://issues.apache.org/jira/browse/COMPRESS-291?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14274065#comment-14274065
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Sascha Zorn edited comment on COMPRESS-291 at 1/12/15 8:03 PM:
---------------------------------------------------------------
I don't want to hijack this bug, as this problem most probably comes from the
very slow buildDecodingStream() call. But it is really unconvenient to not be
able to just "list" all the available files of an archive without
getNextEntry() calling buildDecodingStream() for every single item. This also
makes just listing the content of files unusably slow!
Could someone please come up with a way to either speed up
buildDecodingStream() or at least calling it as late as possible (as for just
listing the names and attributes of files seems to not need
buildDecodingStream)?
was (Author: saschazorn):
I don't want to hijack this bug, as this problem most probably comes from the
very slow buildDecodingStream() call. But it is really unconvenient to not be
able to just "list" all the available files of an archive without
getNextEntry() calling buildDecodingStream() for every single item. This also
makes just listing the content of files unusably slow!
Could someone please come up with a way to either speed up
buildDecodingStream() or at least calling it as late as possible?
> decompress .7z archive very very slow
> -------------------------------------
>
> Key: COMPRESS-291
> URL: https://issues.apache.org/jira/browse/COMPRESS-291
> Project: Commons Compress
> Issue Type: Improvement
> Components: Compressors
> Affects Versions: 1.9
> Environment: Windows 7 x64, jdk1.7.0_21 x64
> Reporter: Robert Jansen
> Priority: Minor
>
> I have 7z archives with one large image and many small files. The following
> code decompresses to a directory and returns the largest file. It is
> glacially slow and not usable for GB size files:
> public File unSevenZipToDir(File sevenZipFile, File outputDir) {
>
> File imgFile = null;
> // Make sure output dir exists
> outputDir.mkdirs();
> if (outputDir.exists()) {
>
> //FileInputStream stream;
> try {
>
> FileOutputStream output = null;
> SevenZFile f7z = new SevenZFile(sevenZipFile);
> SevenZArchiveEntry entry;
> long maxSize = 0;
> while ((entry = f7z.getNextEntry()) != null) {
> if (entry != null) {
> String s = entry.getName();
> if (s != null) {
> long sz =
> entry.getSize();
>
> if (sz > 0) {
> int count;
> byte data[] =
> new byte[4096];
>
> String
> outFileName = outputDir.getPath() + "/"
>
> + new File(entry.getName()).getName();
>
>
>
>
>
>
>
>
>
>
>
>
>
> File outFile =
> new File(outFileName);
>
> // Extract only
> if it does not already exist
> if
> (outFile.exists() == false) {
>
> System.out.println("Extracting " + s + " => size = " + sz);
>
>
>
>
> FileOutputStream fos = new FileOutputStream(
>
> outFile);
>
>
>
> BufferedOutputStream dest = new BufferedOutputStream(
>
> fos);
>
> while
> ((count = f7z.read(data)) != -1) {
>
> dest.write(data, 0, count);
> }
>
>
> dest.flush();
>
> dest.close();
>
> } else {
>
> System.out.println("Using already Extracted " + s + " => size = " + sz);
> }
> if
> (s.endsWith(".h5") || s.endsWith(".tif") ||
>
> s.endsWith(".cos") || s.endsWith(".nitf")
>
> || s.endsWith(".ntf")
>
> || s.endsWith(".jpg") && sz > maxSize) {
> maxSize
> = sz;
> imgFile
> = new File(outFileName);
> }
> } // end sz > 0
> } // end s != null
> } // end if entry
> } // end while
> f7z.close();
> } catch (FileNotFoundException e) {
> // TODO Auto-generated catch block
> e.printStackTrace();
> } catch (IOException e) {
> // TODO Auto-generated catch block
> e.printStackTrace();
> }
> }
> return imgFile;
> }
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