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jar(1) |
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jar−The Java Archive Tool
jar combines multiple files into a single JAR archive file.
Create jar file
jar c[v0Mmfe] [manifest] [jarfile] [entrypoint] [−C dir] inputfiles [−Joption]
Update jar file
jar u[v0Mmfe] [manifest] [jarfile] [entrypoint] [−C dir] inputfiles [−Joption]
Extract jar file
jar x[vf] [jarfile] [inputfiles] [−Joption]
List table of contents of jar file
jar t[vf] [jarfile] [inputfiles] [−Joption]
Add index to jar file
jar i jarfile [−Joption]
where:
cuxtiv0Mmfe
Options that control the jar command.
jarfile
Jar file to be created (c), updated (u), extracted (x), or have its table of contents viewed (t). The −f option and filename jarfile are a pair −− if either is present, they must both appear. Note that omitting f and jarfile accepts a "jar file" from standard input (for x and t) or sends the "jar file" to standard output (for c and u).
inputfiles
Files or directories, separated by spaces, to be combined into jarfile (for c and u), or to be extracted (for x) or listed (for t) from jarfile. All directories are processed recursively. The files are compressed unless option 0 (zero) is used.
manifest
Pre−existing manifest file whose name: value pairs are to be included in MANIFEST.MF in the jar file. The −m option and filename manifest are a pair −− if either is present, they must both appear. The letters m, f and e must appear in the same order that manifest, jarfile, entrypoint appear.
entrypoint
The name of the class that set as the application entry point for stand−alone applications bundled into executable jar file. The −e option and entrypoint are a pair −− if either is present, they must both appear. The letters m, f and e must appear in the same order that manifest, jarfile, entrypoint appear.
−C dir
Temporarily changes directories to dir while processing the following inputfiles argument. Multiple −C dir inputfiles sets are allowed.
−Joption
Option to be passed into the Java runtime environment. (There must be no space between −J and option).
The jar
tool combines multiple files into a single JAR archive file.
jar is a general−purpose archiving and
compression tool, based on ZIP and the ZLIB @
http://www.gzip.org/zlib/ compression format. However,
jar was designed mainly package java applets or
applications into a single archive. When the components of
an applet or application (files, images and sounds) are
combined into a single archive, they can be downloaded by a
java agent (like a browser) in a single HTTP transaction,
rather than requiring a new connection for each piece. This
dramatically improves download times. jar also
compresses files and so further improves download time. In
addition, it allows individual entries in a file to be
signed by the applet author so that their origin can be
authenticated. The syntax for the jar tool is almost
identical to the syntax for the tar command. A
jar archive can be used as a class path @
http://ccc.sfbay/4291383/attachment/classpath.html entry,
whether or not it is compressed.
Typical usage to combine files into a jar file is:
% jar cf myFile.jar *.class
In this
example, all the class files in the current directory are
placed into the file named myFile.jar. The jar tool
automatically generates a manifest file entry named
META−INF/MANIFEST.MF. It is always the first
entry in the jar file. The manifest file declares
meta−information about the archive, and stores that
data as name : value pairs. Refer to the
JAR file specification @
http://ccc.sfbay/guide/jar/jar.html#JAR%20Manifest for
details explaining how the jar tool stores
meta−information in the manifest file.
If a jar file should include name : value pairs contained in an existing manifest file, specify that file using the −m option:
% jar cmf myManifestFile myFile.jar *.class
An existing manifest file must end with a new line character. jar does not parse the last line of a manifest file if it does not end with a new line character.
Note: A jar command that specifies cfm on the command line instead of cmf (the order of the m and −f options are reversed), the jar command line must specify the name of the jar archive first, followed by the name of the manifest file:
% jar cfm myFile.jar myManifestFile *.class
The manifest is in a text format inspired by RFC822 ASCII format, so it is easy to view and process manifest−file contents.
To extract the files from a jar file, use x:
% jar xf myFile.jar
To extract individual files from a jar file, supply their filenames:
% jar xf myFile.jar foo bar
Beginning with
version 1.3 of the Java 2 SDK, the jar utility
supports JarIndex @
http://ccc.sfbay/guide/jar/jar.html#JAR%20Index, which
allows application class loaders to load classes more
efficiently from jar files. If an application or applet is
bundled into multiple jar files, only the necessary
jar files will be downloaded and opened to load classes.
This performance optimization is enabled by running
jar with the −ioption. It will generate
package location information for the specified main jar file
and all the jar files it depends on, which need to be
specified in the Class−Path attribute of the
main jar file’s manifest.
% jar i main.jar
In this
example, an INDEX.LIST file is inserted into the
META−INF directory of main.jar.
The application class loader uses the information stored in
this file for efficient class loading. For details
about how location information is stored in the index file,
refer to the JarIndex specification.
To copy directories, first compress files in dir1 to
stdout, then extract from stdin to dir2
(omitting the −f option from both jar
commands):
% (cd dir1; jar c .) | (cd dir2; jar x)
To review
command samples which use jar to opeate on jar files
and jar file manifests, see Examples, below. Also refer to
the jar trail of the Java Tutorial @
http://java.sun.com/docs/books/tutorial/jar.
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c |
Creates a new archive file named jarfile (if f is specified) or to standard output (if f and jarfile are omitted). Add to it the files and directories specified by inputfiles. | ||
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u |
Updates an existing file jarfile (when f is specified) by adding to it files and directories specified by inputfiles. For example: |
jar uf foo.jar foo.class
would add the file foo.class to the existing jar file foo.jar. The −u option can also update the manifest entry, as given by this example:
jar umf manifest foo.jar
updates the foo.jar manifest with the name : value pairs in manifest.
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x |
Extracts files and directories from jarfile (if f is specified) or standard input (if f and jarfile are omitted). If inputfiles is specified, only those specified files and directories are extracted. Otherwise, all files and directories are extracted. The time and date of the extracted files are those given in the archive. | ||
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t |
Lists the table of contents from jarfile (if f is specified) or standard input (if f and jarfile are omitted). If inputfiles is specified, only those specified files and directories are listed. Otherwise, all files and directories are listed. | ||
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i |
Generate index information for the specified jarfile and its dependent jar files. For example: |
jar i foo.jar
would generate an INDEX.LIST file in foo.jar which contains location information for each package in foo.jar and all the jar files specified in the Class−Path attribute of foo.jar. See the index example.
|
f |
Specifies the file jarfile to be created (c), updated (u), extracted (x), indexed (i), or viewed (t). The −f option and filename jarfile are a pair −− if present, they must both appear. Omitting f and jarfile accepts a jar file name from stdin(for x and t) or sends jar file to stdout (for c and u). | ||
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v |
Generates verbose output to standard output. Examples shown below. | ||
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0 |
(zero) Store without using ZIP compression. | ||
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M |
Do not create a manifest file entry (for c and u), or delete a manifest file entry if one exists (for u). | ||
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m |
Includes name : value attribute pairs from the specified manifest file manifest in the file at META−INF/MANIFEST.MF. jar adds a name : value pair unless an entry already exists with the same name, in which case jar updates its value. |
On the command line, the letters m and f must appear in the same order that manifest and jarfile appear. Example use:
jar cmf myManifestFile myFile.jar *.class
You can add
special−purpose name : value
attribute pairs to the manifest that aren’t contained
in the default manifest. For example, you can add attributes
specifying vendor information, version information, package
sealing, or to make JAR−bundled applications
executable. See the JAR Files @
http://java.sun.com/docs/books/tutorial/jar/ trail in the
Java Tutorial for examples of using the
−m option.
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e |
Sets entrypoint as the application entry point for stand−alone applications bundled into executable jar file. The use of this option creates or overrides the Main−Class attribute value in the manifest file. This option can be used during creation of jar file or while updating the jar file. This option specifies the application entry point without editing or creating the manifest file. |
For example, this command creates Main.jar where the Main−Class attribute value in the manifest is set to Main:
jar cfe Main.jar Main Main.class
The java runtime can directly invoke this application by running the following command:
java −jar Main.jar
If the entrypoint class name is in a package it may use either a dot (".") or slash ("/") character as the delimiter. For example, if Main.class is in a package called foo the entry point can be specified in the following ways:
jar −cfe Main.jar foo/Main foo/Main.class
or
jar −cfe Main.jar foo.Main foo/Main.class
Note: specifying
both −m and −e options together
when the given manifest also contains the
Main−Class attribute results in an ambigous
Main.class specification, leading to an error and the
jar creation or update operation is aborted.
−C dir
Temporarily changes directories
(cd dir) during execution of the jar
command while processing the following inputfiles
argument. Its operation is intended to be similar to the
−C option of the UNIX tar utility.
For example, this command changes to the classes
directory and adds the bar.class from that directory
to foo.jar:
jar uf foo.jar −C classes bar.class
This command changes to the classes directory and adds to foo.jar all files within the classes directory (without creating a classes directory in the jar file), then changes back to the original directory before changing to the bin directory to add xyz.class to foo.jar.
jar uf foo.jar −C classes . −C bin xyz.class
If classes holds files bar1 and bar2, then here’s what the jar file will contain using jar tf foo.jar:
META−INF/
META−INF/MANIFEST.MF
bar1
bar2
xyz.class
−Joption
Pass option to the Java
runtime environment, where option is one of the
options described on the reference page for the java
application launcher @
http://ccc.sfbay/4291383/attachment/java.html#options. For
example, −J−Xmx48M sets the
maximum memory to 48 megabytes. It is a common convention
for −J to pass options to the underlying
runtime environment.
To shorten or simplify the jar command line, you can specify one or more files that themselves contain arguments to the jar command (except −J options). This enables you to create jar commands of any length, overcoming command line limits imposed by the operating system.
An argument file can include options and filenames. The arguments within a file can be space–separated or newline−separated. Filenames within an argument file are relative to the current directory, not relative to the location of the argument file. Wildcards (*) that might otherwise be expanded by the operating system shell are not expanded. Use of the @ character to recursively interpret files is not supported. The −J options are not supported because they are passed to the launcher, which does not support argument files.
When executing
jar, pass in the path and name of each argument file
with the @ leading character. When jar
encounters an argument beginning with the character
@, it expands the contents of that file into the
argument list.
The example below, classes.list holds the names of
files output by a find command:
% find . −name ’*.class’ −print > classes.list
You can then execute the jar command on Classes.list by passing it to jar using argfile syntax:
% jar cf my.jar @classes.list
An argument file can specify a path, but any filenames inside the argument file that have relative paths are relative to the current working directory, not to the path passed in. Here is an example:
% jar @path1/classes.list
To add all the files in a particular directory to an archive (overwriting contents if the archive already exists). Enumerating verbosely (with the −v option) will tell you more information about the files in the archive, such as their size and last modified date.
% ls
1.au Animator.class monkey.jpg
2.au Wave.class spacemusic.au
3.au at_work.gif
% jar cvf
bundle.jar *
added manifest
adding: 1.au(in = 2324) (out= 67)(deflated 97%)
adding: 2.au(in = 6970) (out= 90)(deflated 98%)
adding: 3.au(in = 11616) (out= 108)(deflated 99%)
adding: Animator.class(in = 2266) (out= 66)(deflated 97%)
adding: Wave.class(in = 3778) (out= 81)(deflated 97%)
adding: at_work.gif(in = 6621) (out= 89)(deflated 98%)
adding: monkey.jpg(in = 7667) (out= 91)(deflated 98%)
adding: spacemusic.au(in = 3079) (out= 73)(deflated
97%)
If you already have separate subdirectories for images, audio files and classes, you can combine them into a single jar file:
% ls
−F
audio/ classes/ images/
% jar cvf
bundle.jar audio classes images
added manifest
adding: audio/(in = 0) (out= 0)(stored 0%)
adding: audio/1.au(in = 2324) (out= 67)(deflated 97%)
adding: audio/2.au(in = 6970) (out= 90)(deflated 98%)
adding: audio/3.au(in = 11616) (out= 108)(deflated 99%)
adding: audio/spacemusic.au(in = 3079) (out= 73)(deflated
97%)
adding: classes/(in = 0) (out= 0)(stored 0%)
adding: classes/Animator.class(in = 2266) (out= 66)(deflated
97%)
adding: classes/Wave.class(in = 3778) (out= 81)(deflated
97%)
adding: images/(in = 0) (out= 0)(stored 0%)
adding: images/monkey.jpg(in = 7667) (out= 91)(deflated 98%)
adding: images/at_work.gif(in = 6621) (out= 89)(deflated
98%)
% ls
−F
audio/ bundle.jar classes/ images/
To see the entry names in the jarfile, use the t option:
% jar tf
bundle.jar
META−INF/
META−INF/MANIFEST.MF
audio/1.au
audio/2.au
audio/3.au
audio/spacemusic.au
classes/Animator.class
classes/Wave.class
images/monkey.jpg
images/at_work.gif
To add an index
file to the jar file for speeding up class loading, use the
i option.
Example:
If you split the inter−dependent classes for a stock trade application into three jar files: main.jar, buy.jar, and sell.jar.
If you specify
the Class−path attribute in the main.jar
manifest as:
Class−Path: buy.jar sell.jar
then you can
use the −i option to speed up the class loading
time for your application:
% jar i main.jar
An INDEX.LIST file is inserted to the META−INF directory. This enables the application class loader to download the specified jar files when it is searching for classes or resources.
The Jar
Overview @
http://ccc.sfbay/guide/jar/jarGuide.html
The Jar File
Specification @
http://ccc.sfbay/guide/jar/jar.html
The JarIndex
Spec @
http://ccc.sfbay/guide/jar/jar.html#JAR%20Index
Jar
Tutorial @
http://java.sun.com/docs/books/tutorial/jar on the Java
Software web site.
pack200
Reference Page @
http://ccc.sfbay/4291383/share/pack200.html
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jar(1) | |