Module java.base

Package java.util.jar

Class JarFile

java.lang.Object

java.util.zip.ZipFile

java.util.jar.JarFile

All Implemented Interfaces:

Closeable, AutoCloseable

public class JarFile
extends ZipFile

The JarFile class is used to read the contents of a jar file from any file that can be opened with java.io.RandomAccessFile. It extends the class java.util.zip.ZipFile with support for reading an optional Manifest entry, and support for processing multi-release jar files. The Manifest can be used to specify meta-information about the jar file and its entries.

A multi-release jar file is a jar file that contains a manifest with a main attribute named "Multi-Release", a set of "base" entries, some of which are public classes with public or protected methods that comprise the public interface of the jar file, and a set of "versioned" entries contained in subdirectories of the "META-INF/versions" directory. The versioned entries are partitioned by the major version of the Java platform. A versioned entry, with a version n, 8 < n, in the "META-INF/versions/{n}" directory overrides the base entry as well as any entry with a version number i where 8 < i < n.

By default, a JarFile for a multi-release jar file is configured to process the multi-release jar file as if it were a plain (unversioned) jar file, and as such an entry name is associated with at most one base entry. The JarFile may be configured to process a multi-release jar file by creating the JarFile with the JarFile(File, boolean, int, Release) constructor. The Release object sets a maximum version used when searching for versioned entries. When so configured, an entry name can correspond with at most one base entry and zero or more versioned entries. A search is required to associate the entry name with the latest versioned entry whose version is less than or equal to the maximum version (see getEntry(String)).

Class loaders that utilize JarFile to load classes from the contents of JarFile entries should construct the JarFile by invoking the JarFile(File, boolean, int, Release) constructor with the value Release.RUNTIME assigned to the last argument. This assures that classes compatible with the major version of the running JVM are loaded from multi-release jar files.

If the verify flag is on when opening a signed jar file, the content of the file is verified against its signature embedded inside the file. Please note that the verification process does not include validating the signer's certificate. A caller should inspect the return value of JarEntry.getCodeSigners() to further determine if the signature can be trusted.

Unless otherwise noted, passing a null argument to a constructor or method in this class will cause a NullPointerException to be thrown.

Implementation Note:

If the API can not be used to configure a JarFile (e.g. to override the configuration of a compiled application or library), two System properties are available.

• jdk.util.jar.version can be assigned a value that is the String representation of a non-negative integer <= Version.current().major(). The value is used to set the effective runtime version to something other than the default value obtained by evaluating Version.current().major(). The effective runtime version is the version that the JarFile(File, boolean, int, Release) constructor uses when the value of the last argument is Release.RUNTIME.
• jdk.util.jar.enableMultiRelease can be assigned one of the three String values true, false, or force. The value true, the default value, enables multi-release jar file processing. The value false disables multi-release jar processing, ignoring the "Multi-Release" manifest attribute, and the versioned directories in a multi-release jar file if they exist. Furthermore, the method isMultiRelease() returns false. The value force causes the JarFile to be initialized to runtime versioning after construction. It effectively does the same as this code: (new JarFile(File, boolean, int, Release.RUNTIME).

Since:

1.2

See Also:

Manifest, ZipFile, JarEntry

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	JarFile.Release A set of constants that represent the entries in either the base directory or one of the versioned directories in a multi-release jar file.

Field Summary

Fields

Modifier and Type	Field and Description
static int	CENATT
static int	CENATX
static int	CENCOM
static int	CENCRC
static int	CENDSK
static int	CENEXT
static int	CENFLG
static int	CENHDR
static int	CENHOW
static int	CENLEN
static int	CENNAM
static int	CENOFF
static long	CENSIG
static int	CENSIZ
static int	CENTIM
static int	CENVEM
static int	CENVER
static int	ENDCOM
static int	ENDHDR
static int	ENDOFF
static long	ENDSIG
static int	ENDSIZ
static int	ENDSUB
static int	ENDTOT
static int	EXTCRC
static int	EXTHDR
static int	EXTLEN
static long	EXTSIG
static int	EXTSIZ
static int	LOCCRC
static int	LOCEXT
static int	LOCFLG
static int	LOCHDR
static int	LOCHOW
static int	LOCLEN
static int	LOCNAM
static long	LOCSIG
static int	LOCSIZ
static int	LOCTIM
static int	LOCVER
static String	MANIFEST_NAME The JAR manifest file name.

Fields inherited from class java.util.zip.ZipFile

OPEN_DELETE, OPEN_READ

Constructor Summary

Constructors

Constructor and Description
JarFile(File file) Creates a new JarFile to read from the specified File object.
JarFile(File file, boolean verify) Creates a new JarFile to read from the specified File object.
JarFile(File file, boolean verify, int mode) Creates a new JarFile to read from the specified File object in the specified mode.
JarFile(File file, boolean verify, int mode, JarFile.Release version) Creates a new JarFile to read from the specified File object in the specified mode.
JarFile(String name) Creates a new JarFile to read from the specified file name.
JarFile(String name, boolean verify) Creates a new JarFile to read from the specified file name.

Method Summary

Modifier and Type	Method and Description
Enumeration<JarEntry>	entries() Returns an enumeration of the jar file entries.
ZipEntry	getEntry(String name) Returns the ZipEntry for the given base entry name or null if not found.
InputStream	getInputStream(ZipEntry ze) Returns an input stream for reading the contents of the specified zip file entry.
JarEntry	getJarEntry(String name) Returns the JarEntry for the given base entry name or null if not found.
Manifest	getManifest() Returns the jar file manifest, or null if none.
JarFile.Release	getVersion() Returns the maximum version used when searching for versioned entries.
boolean	isMultiRelease() Indicates whether or not this jar file is a multi-release jar file.
Stream<JarEntry>	stream() Returns an ordered Stream over all the jar file entries.

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from class java.util.zip.ZipFile

close, finalize, getComment, getName, size

Field Detail

CENATT

public static final int CENATT

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Constant Field Values

CENATX

public static final int CENATX

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CENCOM

public static final int CENCOM

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CENCRC

public static final int CENCRC

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CENDSK

public static final int CENDSK

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CENEXT

public static final int CENEXT

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CENFLG

public static final int CENFLG

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CENHDR

public static final int CENHDR

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CENHOW

public static final int CENHOW

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CENLEN

public static final int CENLEN

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CENNAM

public static final int CENNAM

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CENOFF

public static final int CENOFF

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CENSIG

public static final long CENSIG

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CENSIZ

public static final int CENSIZ

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CENTIM

public static final int CENTIM

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CENVEM

public static final int CENVEM

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CENVER

public static final int CENVER

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ENDCOM

public static final int ENDCOM

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ENDHDR

public static final int ENDHDR

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ENDOFF

public static final int ENDOFF

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ENDSIG

public static final long ENDSIG

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ENDSIZ

public static final int ENDSIZ

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ENDSUB

public static final int ENDSUB

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ENDTOT

public static final int ENDTOT

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EXTCRC

public static final int EXTCRC

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EXTHDR

public static final int EXTHDR

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EXTLEN

public static final int EXTLEN

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EXTSIG

public static final long EXTSIG

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EXTSIZ

public static final int EXTSIZ

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LOCCRC

public static final int LOCCRC

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LOCEXT

public static final int LOCEXT

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LOCFLG

public static final int LOCFLG

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LOCHDR

public static final int LOCHDR

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LOCHOW

public static final int LOCHOW

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LOCLEN

public static final int LOCLEN

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LOCNAM

public static final int LOCNAM

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LOCSIG

public static final long LOCSIG

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LOCSIZ

public static final int LOCSIZ

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LOCTIM

public static final int LOCTIM

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LOCVER

public static final int LOCVER

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MANIFEST_NAME

public static final String MANIFEST_NAME

The JAR manifest file name.

See Also:

Constant Field Values

Constructor Detail

JarFile

public JarFile(File file)
        throws IOException

Creates a new JarFile to read from the specified File object. The JarFile will be verified if it is signed.

Parameters:

file - the jar file to be opened for reading

Throws:

IOException - if an I/O error has occurred

SecurityException - if access to the file is denied by the SecurityManager

JarFile

public JarFile(File file,
               boolean verify)
        throws IOException

Creates a new JarFile to read from the specified File object.

Parameters:

file - the jar file to be opened for reading

verify - whether or not to verify the jar file if it is signed.

Throws:

IOException - if an I/O error has occurred

SecurityException - if access to the file is denied by the SecurityManager.

JarFile

public JarFile(File file,
               boolean verify,
               int mode)
        throws IOException

Creates a new JarFile to read from the specified File object in the specified mode. The mode argument must be either OPEN_READ or OPEN_READ | OPEN_DELETE.

Parameters:

file - the jar file to be opened for reading

verify - whether or not to verify the jar file if it is signed.

mode - the mode in which the file is to be opened

Throws:

IOException - if an I/O error has occurred

IllegalArgumentException - if the mode argument is invalid

SecurityException - if access to the file is denied by the SecurityManager

Since:

1.3

JarFile

public JarFile(File file,
               boolean verify,
               int mode,
               JarFile.Release version)
        throws IOException

Creates a new JarFile to read from the specified File object in the specified mode. The mode argument must be either OPEN_READ or OPEN_READ | OPEN_DELETE. The version argument configures the JarFile for processing multi-release jar files.

Parameters:

file - the jar file to be opened for reading

verify - whether or not to verify the jar file if it is signed.

mode - the mode in which the file is to be opened

version - specifies the release version for a multi-release jar file

Throws:

IOException - if an I/O error has occurred

IllegalArgumentException - if the mode argument is invalid

SecurityException - if access to the file is denied by the SecurityManager

NullPointerException - if version is null

Since:

9

JarFile

public JarFile(String name)
        throws IOException

Creates a new JarFile to read from the specified file name. The JarFile will be verified if it is signed.

Parameters:

name - the name of the jar file to be opened for reading

Throws:

IOException - if an I/O error has occurred

SecurityException - if access to the file is denied by the SecurityManager

JarFile

public JarFile(String name,
               boolean verify)
        throws IOException

Creates a new JarFile to read from the specified file name.

Parameters:

name - the name of the jar file to be opened for reading

verify - whether or not to verify the jar file if it is signed.

Throws:

IOException - if an I/O error has occurred

SecurityException - if access to the file is denied by the SecurityManager

Method Detail

getVersion

public final JarFile.Release getVersion()

Returns the maximum version used when searching for versioned entries.

Returns:

the maximum version, or Release.BASE if this jar file is processed as if it is an unversioned jar file or is not a multi-release jar file

Since:

9

isMultiRelease

public final boolean isMultiRelease()

Indicates whether or not this jar file is a multi-release jar file.

Returns:

true if this JarFile is a multi-release jar file

Since:

9

getManifest

public Manifest getManifest()
                     throws IOException

Returns the jar file manifest, or null if none.

Returns:

the jar file manifest, or null if none

Throws:

IllegalStateException - may be thrown if the jar file has been closed

IOException - if an I/O error has occurred

getJarEntry

public JarEntry getJarEntry(String name)

Returns the JarEntry for the given base entry name or null if not found.

If this JarFile is a multi-release jar file and is configured to be processed as such, then a search is performed to find and return a JarEntry that is the latest versioned entry associated with the given entry name. The returned JarEntry is the versioned entry corresponding to the given base entry name prefixed with the string "META-INF/versions/{n}/", for the largest value of n for which an entry exists. If such a versioned entry does not exist, then the JarEntry for the base entry is returned, otherwise null is returned if no entries are found. The initial value for the version n is the maximum version as returned by the method getVersion().

Implementation Requirements:

This implementation invokes getEntry(String).

Parameters:

name - the jar file entry name

Returns:

the JarEntry for the given entry name, or the versioned entry name, or null if not found

Throws:

IllegalStateException - may be thrown if the jar file has been closed

See Also:

JarEntry

getEntry

public ZipEntry getEntry(String name)

Returns the ZipEntry for the given base entry name or null if not found.

If this JarFile is a multi-release jar file and is configured to be processed as such, then a search is performed to find and return a ZipEntry that is the latest versioned entry associated with the given entry name. The returned ZipEntry is the versioned entry corresponding to the given base entry name prefixed with the string "META-INF/versions/{n}/", for the largest value of n for which an entry exists. If such a versioned entry does not exist, then the ZipEntry for the base entry is returned, otherwise null is returned if no entries are found. The initial value for the version n is the maximum version as returned by the method getVersion().

Overrides:

getEntry in class ZipFile

Implementation Requirements:

This implementation may return a versioned entry for the requested name even if there is not a corresponding base entry. This can occur if there is a private or package-private versioned entry that matches. If a subclass overrides this method, assure that the override method invokes super.getEntry(name) to obtain all versioned entries.

Parameters:

name - the jar file entry name

Returns:

the ZipEntry for the given entry name or the versioned entry name or null if not found

Throws:

IllegalStateException - may be thrown if the jar file has been closed

See Also:

ZipEntry

entries

public Enumeration<JarEntry> entries()

Returns an enumeration of the jar file entries. The set of entries returned depends on whether or not the jar file is a multi-release jar file, and on the constructor used to create the JarFile. If the jar file is not a multi-release jar file, all entries are returned, regardless of how the JarFile is created. If the constructor does not take a Release argument, all entries are returned. If the jar file is a multi-release jar file and the constructor takes a Release argument, then the set of entries returned is equivalent to the set of entries that would be returned if the set was built by invoking getEntry(String) or getJarEntry(String) with the name of each base entry in the jar file. A base entry is an entry whose path name does not start with "META-INF/versions/".

Overrides:

entries in class ZipFile

Returns:

an enumeration of the jar file entries

Throws:

IllegalStateException - may be thrown if the jar file has been closed

stream

public Stream<JarEntry> stream()

Returns an ordered Stream over all the jar file entries. Entries appear in the Stream in the order they appear in the central directory of the jar file. The set of entries returned depends on whether or not the jar file is a multi-release jar file, and on the constructor used to create the JarFile. If the jar file is not a multi-release jar file, all entries are returned, regardless of how the JarFile is created. If the constructor does not take a Release argument, all entries are returned. If the jar file is a multi-release jar file and the constructor takes a Release argument, then the set of entries returned is equivalent to the set of entries that would be returned if the set was built by invoking getEntry(String) or getJarEntry(String) with the name of each base entry in the jar file. A base entry is an entry whose path name does not start with "META-INF/versions/".

Overrides:

stream in class ZipFile

Returns:

an ordered Stream of entries in this jar file

Throws:

IllegalStateException - if the jar file has been closed

Since:

1.8

getInputStream

public InputStream getInputStream(ZipEntry ze)
                           throws IOException

Returns an input stream for reading the contents of the specified zip file entry.

Overrides:

getInputStream in class ZipFile

Parameters:

ze - the zip file entry

Returns:

an input stream for reading the contents of the specified zip file entry

Throws:

ZipException - if a zip file format error has occurred

IOException - if an I/O error has occurred

SecurityException - if any of the jar file entries are incorrectly signed.

IllegalStateException - may be thrown if the jar file has been closed