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<?xml version="1.0"?> |
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<document xmlns="http://maven.apache.org/XDOC/2.0" |
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" |
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xsi:schemaLocation="http://maven.apache.org/XDOC/2.0 https://maven.apache.org/xsd/xdoc-2.0.xsd"> |
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<properties> |
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<title>Overview</title> |
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<author email="dev@commons.apache.org">Apache Commons Team</author> |
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</properties> |
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<body> |
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<section name="Apache Commons Compress™"> |
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<p> |
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The Apache Commons Compress library defines an API for |
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working with ar, cpio, Unix dump, tar, zip, gzip, XZ, |
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Pack200, bzip2, 7z, arj, LZMA, snappy, DEFLATE, lz4, |
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Brotli, Zstandard, DEFLATE64 and Z files. |
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</p> |
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<p> |
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The code in this component has many origins: |
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</p> |
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<ul> |
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<li>The bzip2, tar and zip support came from Avalon's |
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Excalibur, but originally from Ant, as far as life in |
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Apache goes. The tar package is originally Tim Endres' |
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public domain package. The bzip2 package is based on |
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the work done by Keiron Liddle as well as Julian Seward's |
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<a href="http://www.bzip.org/index.html">libbzip2</a>. |
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It has migrated |
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via:<br/> Ant -> Avalon-Excalibur -> Commons-IO |
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-> Commons-Compress.</li> |
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<li>The cpio package has been contributed by Michael Kuss |
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and |
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the <a href="http://jrpm.sourceforge.net/">jRPM</a> |
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project.</li> |
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<li>The pack200 code has originally been part of the now |
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retired <a href="https://harmony.apache.org/">Apache |
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Harmony™</a> project.</li> |
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</ul> |
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</section> |
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<section name="Status"> |
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<p>The current release requires Java 8 or above.</p> |
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<p>For a list of changes see the <a href="changes.html">Changes Report</a>.</p> |
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</section> |
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<section name="Documentation"> |
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<p>The compress component is split into <em>compressors</em> and |
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<em>archivers</em>. While <em>compressors</em> |
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(un)compress streams that usually store a single |
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entry, <em>archivers</em> deal with archives that contain |
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structured content represented |
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by <code>ArchiveEntry</code> instances which in turn |
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usually correspond to single files or directories.</p> |
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<p>Currently the bzip2, Pack200, XZ, gzip, LZMA, brotli, |
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Zstandard and Z formats are |
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supported as compressors where gzip support is mostly provided by |
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the <code>java.util.zip</code> package of the Java |
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class library. XZ and LZMA support is provided by the public |
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domain <a href="https://tukaani.org/xz/java.html">XZ for |
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Java</a> library. Brotli support is provided by the MIT |
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licensed <a href="https://github.com/google/brotli">Google |
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Brotli decoder</a>. Zstandard support is provided by the BSD |
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licensed <a href="https://github.com/luben/zstd-jni">Zstd-jni</a>. |
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As of Commons Compress 1.21 support for the DEFLATE64, Z and Brotli |
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formats is read-only.</p> |
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<p>The ar, arj, cpio, dump, tar, 7z and zip formats are supported as |
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archivers where the <a href="zip.html">zip</a> |
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implementation provides capabilities that go beyond the |
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features found in java.util.zip. As of Commons Compress |
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1.21 support for the dump and arj formats is |
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read-only - 7z can read most compressed and encrypted |
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archives but only write unencrypted ones. LZMA(2) support |
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in 7z requires <a href="https://tukaani.org/xz/java.html">XZ for |
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Java</a> as well.</p> |
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<p>The compress component provides abstract base classes for |
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compressors and archivers together with factories that can |
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be used to choose implementations by algorithm name. In |
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the case of input streams the factories can also be used |
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to guess the format and provide the matching |
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implementation.</p> |
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<ul> |
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<li>The <a href="examples.html">user guide</a> contains |
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more detailed information and some examples.</li> |
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<li>The <a href="limitations.html">known limitations and |
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problems</a> page lists the currently known problems |
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grouped by the format they apply to.</li> |
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<li>The <a href="apidocs/index.html">Javadoc</a> of the latest GIT</li> |
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<li>The <a href="https://gitbox.apache.org/repos/asf?p=commons-compress.git">GIT |
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repository</a> can be browsed.</li> |
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</ul> |
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</section> |
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<section name="Releases"> |
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<p> |
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<a href="https://commons.apache.org/compress/download_compress.cgi">Download now!</a> |
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</p> |
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</section> |
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</body> |
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</document> |
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