src/main/java/org/apache/commons/compress/compressors/pack200/package.html - platform/external/apache-commons-compress - Git at Google

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     <p>Provides stream classes for compressing and decompressing
       streams using the Pack200 algorithm used to compress Java
       archives.</p>

     <p>The streams of this package only work on JAR archives, i.e. a
       {@link
       org.apache.commons.compress.compressors.pack200.Pack200CompressorOutputStream
       Pack200CompressorOutputStream} expects to be wrapped around a
       stream that a valid JAR archive will be written to and a {@link
       org.apache.commons.compress.compressors.pack200.Pack200CompressorInputStream
       Pack200CompressorInputStream} provides a stream to read from a
       JAR archive.</p>

     <p>JAR archives compressed with Pack200 will in general be
       different from the original archive when decompressed again.
       For details see
       the <a href="https://download.oracle.com/javase/1.5.0/docs/api/java/util/jar/Pack200.html">API
       documentation of Pack200</a>.</p>

     <p>The streams of this package work on non-deflated streams,
       i.e. archives like those created with the <code>--no-gzip</code>
       option of the JDK's <code>pack200</code> command line tool.  If
       you want to work on deflated streams you must use an additional
       stream layer - for example by using Apache Commons Compress'
       gzip package.</p>

     <p>The Pack200 API provided by the Java class library doesn't lend
       itself to real stream
       processing.  <code>Pack200CompressorInputStream</code> will
       uncompress its input immediately and then provide
       an <code>InputStream</code> to a cached result.
       Likewise <code>Pack200CompressorOutputStream</code> will not
       write anything to the given OutputStream
       until <code>finish</code> or <code>close</code> is called - at
       which point the cached output written so far gets
       compressed.</p>

     <p>Two different caching modes are available - "in memory", which
       is the default, and "temporary file".  By default data is cached
       in memory but you should switch to the temporary file option if
       your archives are really big.</p>

     <p>Given there always is an intermediate result
       the <code>getBytesRead</code> and <code>getCount</code> methods
       of <code>Pack200CompressorInputStream</code> are meaningless
       (read from the real stream or from the intermediate result?)
       and always return 0.</p>

     <p>During development of the initial version several attempts have
       been made to use a real streaming API based for example
       on <code>Piped(In|Out)putStream</code> or explicit stream
       pumping like Commons Exec's <code>InputStreamPumper</code> but
       they have all failed because they rely on the output end to be
       consumed completely or else the <code>(un)pack</code> will block
       forever.  Especially for <code>Pack200InputStream</code> it is
       very likely that it will be wrapped in
       a <code>ZipArchiveInputStream</code> which will never read the
       archive completely as it is not interested in the ZIP central
       directory data at the end of the JAR archive.</p>

   </body>
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	(the "License"); you may not use this file except in compliance with
	the License. You may obtain a copy of the License at

	http://www.apache.org/licenses/LICENSE-2.0

	Unless required by applicable law or agreed to in writing, software
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	<body>
	<p>Provides stream classes for compressing and decompressing
	streams using the Pack200 algorithm used to compress Java
	archives.</p>

	<p>The streams of this package only work on JAR archives, i.e. a
	{@link
	org.apache.commons.compress.compressors.pack200.Pack200CompressorOutputStream
	Pack200CompressorOutputStream} expects to be wrapped around a
	stream that a valid JAR archive will be written to and a {@link
	org.apache.commons.compress.compressors.pack200.Pack200CompressorInputStream
	Pack200CompressorInputStream} provides a stream to read from a
	JAR archive.</p>

	<p>JAR archives compressed with Pack200 will in general be
	different from the original archive when decompressed again.
	For details see
	the <a href="https://download.oracle.com/javase/1.5.0/docs/api/java/util/jar/Pack200.html">API
	documentation of Pack200</a>.</p>

	<p>The streams of this package work on non-deflated streams,
	i.e. archives like those created with the <code>--no-gzip</code>
	option of the JDK's <code>pack200</code> command line tool. If
	you want to work on deflated streams you must use an additional
	stream layer - for example by using Apache Commons Compress'
	gzip package.</p>

	<p>The Pack200 API provided by the Java class library doesn't lend
	itself to real stream
	processing. <code>Pack200CompressorInputStream</code> will
	uncompress its input immediately and then provide
	an <code>InputStream</code> to a cached result.
	Likewise <code>Pack200CompressorOutputStream</code> will not
	write anything to the given OutputStream
	until <code>finish</code> or <code>close</code> is called - at
	which point the cached output written so far gets
	compressed.</p>

	<p>Two different caching modes are available - "in memory", which
	is the default, and "temporary file". By default data is cached
	in memory but you should switch to the temporary file option if
	your archives are really big.</p>

	<p>Given there always is an intermediate result
	the <code>getBytesRead</code> and <code>getCount</code> methods
	of <code>Pack200CompressorInputStream</code> are meaningless
	(read from the real stream or from the intermediate result?)
	and always return 0.</p>

	<p>During development of the initial version several attempts have
	been made to use a real streaming API based for example
	on <code>Piped(In\|Out)putStream</code> or explicit stream
	pumping like Commons Exec's <code>InputStreamPumper</code> but
	they have all failed because they rely on the output end to be
	consumed completely or else the <code>(un)pack</code> will block
	forever. Especially for <code>Pack200InputStream</code> it is
	very likely that it will be wrapped in
	a <code>ZipArchiveInputStream</code> which will never read the
	archive completely as it is not interested in the ZIP central
	directory data at the end of the JAR archive.</p>

	</body>
	</html>