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, Runtime.Version) constructor. The Runtime.Version 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, Runtime.Version) constructor with the value Runtime.version() 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 jar entry is verified against the signature embedded inside the manifest that is associated with its path name. For a multi-release jar file, the content of a versioned entry is verified against its own signature and JarEntry.getCodeSigners() returns its own signers.

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 <= Runtime.version().feature(). The value is used to set the effective runtime version to something other than the default value obtained by evaluating Runtime.version().feature(). The effective runtime version is the version that the JarFile(File, boolean, int, Runtime.Version) constructor uses when the value of the last argument is JarFile.runtimeVersion().
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, JarFile.runtimeVersion()).

Since:

1.2

See Also:

Field Summary

Modifier and Type	Field	Description
`static final int`	`CENATT`	Central directory (CEN) header internal file attributes field offset.
`static final int`	`CENATX`	Central directory (CEN) header external file attributes field offset.
`static final int`	`CENCOM`	Central directory (CEN) header comment length field offset.
`static final int`	`CENCRC`	Central directory (CEN) header uncompressed file crc-32 value field offset.
`static final int`	`CENDSK`	Central directory (CEN) header disk number start field offset.
`static final int`	`CENEXT`	Central directory (CEN) header extra field length field offset.
`static final int`	`CENFLG`	Central directory (CEN) header encrypt, decrypt flags field offset.
`static final int`	`CENHDR`	Central directory (CEN) header size in bytes (including signature).
`static final int`	`CENHOW`	Central directory (CEN) header compression method field offset.
`static final int`	`CENLEN`	Central directory (CEN) header uncompressed size field offset.
`static final int`	`CENNAM`	Central directory (CEN) header filename length field offset.
`static final int`	`CENOFF`	Central directory (CEN) header LOC header offset field offset.
`static final long`	`CENSIG`	Central directory (CEN) header signature.
`static final int`	`CENSIZ`	Central directory (CEN) header compressed size field offset.
`static final int`	`CENTIM`	Central directory (CEN) header modification time field offset.
`static final int`	`CENVEM`	Central directory (CEN) header version made by field offset.
`static final int`	`CENVER`	Central directory (CEN) header version needed to extract field offset.
`static final int`	`ENDCOM`	End of central directory (END) header ZIP file comment length field offset.
`static final int`	`ENDHDR`	End of central directory (END) header size in bytes (including signature).
`static final int`	`ENDOFF`	End of central directory (END) header offset for the first CEN header field offset.
`static final long`	`ENDSIG`	End of central directory (END) header signature.
`static final int`	`ENDSIZ`	End of central directory (END) header central directory size in bytes field offset.
`static final int`	`ENDSUB`	End of central directory (END) header number of entries on this disk field offset.
`static final int`	`ENDTOT`	End of central directory (END) header total number of entries field offset.
`static final int`	`EXTCRC`	Extra local (EXT) header uncompressed file crc-32 value field offset.
`static final int`	`EXTHDR`	Extra local (EXT) header size in bytes (including signature).
`static final int`	`EXTLEN`	Extra local (EXT) header uncompressed size field offset.
`static final long`	`EXTSIG`	Extra local (EXT) header signature.
`static final int`	`EXTSIZ`	Extra local (EXT) header compressed size field offset.
`static final int`	`LOCCRC`	Local file (LOC) header uncompressed file crc-32 value field offset.
`static final int`	`LOCEXT`	Local file (LOC) header extra field length field offset.
`static final int`	`LOCFLG`	Local file (LOC) header general purpose bit flag field offset.
`static final int`	`LOCHDR`	Local file (LOC) header size in bytes (including signature).
`static final int`	`LOCHOW`	Local file (LOC) header compression method field offset.
`static final int`	`LOCLEN`	Local file (LOC) header uncompressed size field offset.
`static final int`	`LOCNAM`	Local file (LOC) header filename length field offset.
`static final long`	`LOCSIG`	Local file (LOC) header signature.
`static final int`	`LOCSIZ`	Local file (LOC) header compressed size field offset.
`static final int`	`LOCTIM`	Local file (LOC) header modification time field offset.
`static final int`	`LOCVER`	Local file (LOC) header version needed to extract field offset.
`static final String`	`MANIFEST_NAME`	The JAR manifest file name.

Fields declared in class ZipFile

OPEN_DELETE, OPEN_READ

Modifier and Type	Field	Description
`static final int`	`OPEN_DELETE`	Mode flag to open a ZIP file and mark it for deletion.
`static final int`	`OPEN_READ`	Mode flag to open a ZIP file for reading.

Constructor Summary

Constructor	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, Runtime.Version 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	Description
`static Runtime.Version`	`baseVersion()`	Returns the version that represents the unversioned configuration of a multi-release jar file.
`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.
`final Runtime.Version`	`getVersion()`	Returns the maximum version used when searching for versioned entries.
`final boolean`	`isMultiRelease()`	Indicates whether or not this jar file is a multi-release jar file.
`static Runtime.Version`	`runtimeVersion()`	Returns the version that represents the effective runtime versioned configuration of a multi-release jar file.
`Stream<JarEntry>`	`stream()`	Returns an ordered `Stream` over the jar file entries.
`Stream<JarEntry>`	`versionedStream()`	Returns a `Stream` of the versioned jar file entries.

Methods declared in class ZipFile

close, getComment, getName, size, toString

Modifier and Type	Method	Description
`void`	`close()`	Closes the ZIP file.
`String`	`getComment()`	Returns the ZIP file comment.
`String`	`getName()`	Returns the path name of the ZIP file.
`int`	`size()`	Returns the number of entries in the ZIP file.
`String`	`toString()`	Returns a string identifying this `ZipFile`, for debugging.

Methods declared in class Object

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

Modifier and Type	Method	Description
`protected Object`	`clone()`	Creates and returns a copy of this object.
`boolean`	`equals(Object obj)`	Indicates whether some other object is "equal to" this one.
`protected void`	`finalize()`	Deprecated, for removal: This API element is subject to removal in a future version. Finalization is deprecated and subject to removal in a future release.
`final Class<?>`	`getClass()`	Returns the runtime class of this `Object`.
`int`	`hashCode()`	Returns a hash code value for this object.
`final void`	`notify()`	Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()`	Wakes up all threads that are waiting on this object's monitor.
`final void`	`wait()`	Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
`final void`	`wait(long timeoutMillis)`	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis, int nanos)`	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

Field Details

MANIFEST_NAME

public static final String MANIFEST_NAME

The JAR manifest file name.

See Also:

LOCSIG

static final long LOCSIG

Local file (LOC) header signature.

See Also:

EXTSIG

static final long EXTSIG

Extra local (EXT) header signature.

See Also:

CENSIG

static final long CENSIG

Central directory (CEN) header signature.

See Also:

ENDSIG

static final long ENDSIG

End of central directory (END) header signature.

See Also:

LOCHDR

static final int LOCHDR

Local file (LOC) header size in bytes (including signature).

See Also:

EXTHDR

static final int EXTHDR

Extra local (EXT) header size in bytes (including signature).

See Also:

CENHDR

static final int CENHDR

Central directory (CEN) header size in bytes (including signature).

See Also:

ENDHDR

static final int ENDHDR

End of central directory (END) header size in bytes (including signature).

See Also:

LOCVER

static final int LOCVER

Local file (LOC) header version needed to extract field offset.

See Also:

LOCFLG

static final int LOCFLG

Local file (LOC) header general purpose bit flag field offset.

See Also:

LOCHOW

static final int LOCHOW

Local file (LOC) header compression method field offset.

See Also:

LOCTIM

static final int LOCTIM

Local file (LOC) header modification time field offset.

See Also:

LOCCRC

static final int LOCCRC

Local file (LOC) header uncompressed file crc-32 value field offset.

See Also:

LOCSIZ

static final int LOCSIZ

Local file (LOC) header compressed size field offset.

See Also:

LOCLEN

static final int LOCLEN

Local file (LOC) header uncompressed size field offset.

See Also:

LOCNAM

static final int LOCNAM

Local file (LOC) header filename length field offset.

See Also:

LOCEXT

static final int LOCEXT

Local file (LOC) header extra field length field offset.

See Also:

EXTCRC

static final int EXTCRC

Extra local (EXT) header uncompressed file crc-32 value field offset.

See Also:

EXTSIZ

static final int EXTSIZ

Extra local (EXT) header compressed size field offset.

See Also:

EXTLEN

static final int EXTLEN

Extra local (EXT) header uncompressed size field offset.

See Also:

CENVEM

static final int CENVEM

Central directory (CEN) header version made by field offset.

See Also:

CENVER

static final int CENVER

Central directory (CEN) header version needed to extract field offset.

See Also:

CENFLG

static final int CENFLG

Central directory (CEN) header encrypt, decrypt flags field offset.

See Also:

CENHOW

static final int CENHOW

Central directory (CEN) header compression method field offset.

See Also:

CENTIM

static final int CENTIM

Central directory (CEN) header modification time field offset.

See Also:

CENCRC

static final int CENCRC

Central directory (CEN) header uncompressed file crc-32 value field offset.

See Also:

CENSIZ

static final int CENSIZ

Central directory (CEN) header compressed size field offset.

See Also:

CENLEN

static final int CENLEN

Central directory (CEN) header uncompressed size field offset.

See Also:

CENNAM

static final int CENNAM

Central directory (CEN) header filename length field offset.

See Also:

CENEXT

static final int CENEXT

Central directory (CEN) header extra field length field offset.

See Also:

CENCOM

static final int CENCOM

Central directory (CEN) header comment length field offset.

See Also:

CENDSK

static final int CENDSK

Central directory (CEN) header disk number start field offset.

See Also:

CENATT

static final int CENATT

Central directory (CEN) header internal file attributes field offset.

See Also:

CENATX

static final int CENATX

Central directory (CEN) header external file attributes field offset.

See Also:

CENOFF

static final int CENOFF

Central directory (CEN) header LOC header offset field offset.

See Also:

ENDSUB

static final int ENDSUB

End of central directory (END) header number of entries on this disk field offset.

See Also:

ENDTOT

static final int ENDTOT

End of central directory (END) header total number of entries field offset.

See Also:

ENDSIZ

static final int ENDSIZ

End of central directory (END) header central directory size in bytes field offset.

See Also:

ENDOFF

static final int ENDOFF

End of central directory (END) header offset for the first CEN header field offset.

See Also:

ENDCOM

static final int ENDCOM

End of central directory (END) header ZIP file comment length field offset.

See Also:

Constructor Details

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

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

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

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

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
Since:: 1.3

JarFile

public JarFile(File file, boolean verify, int mode, Runtime.Version 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, after being converted to a canonical form, is used to configure the JarFile for processing multi-release jar files.

The canonical form derived from the version parameter is Runtime.Version.parse(Integer.toString(n)) where n is Math.max(version.feature(), JarFile.baseVersion().feature()).

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; NullPointerException - if version is null
Since:: 9

Method Details

baseVersion

public static Runtime.Version baseVersion()

Returns the version that represents the unversioned configuration of a multi-release jar file.

Returns:: the version that represents the unversioned configuration
Since:: 9

runtimeVersion

public static Runtime.Version runtimeVersion()

Returns the version that represents the effective runtime versioned configuration of a multi-release jar file.

By default the feature version number of the returned Version will be equal to the feature version number of Runtime.version(). However, if the jdk.util.jar.version property is set, the returned Version is derived from that property and feature version numbers may not be equal.

Returns:: the version that represents the runtime versioned configuration
Since:: 9

getVersion

public final Runtime.Version getVersion()

Returns the maximum version used when searching for versioned entries.

If this JarFile is not a multi-release jar file or is not configured to be processed as such, then the version returned will be the same as that returned from baseVersion().

Returns:: the maximum version
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:

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:

entries

public Enumeration<JarEntry> entries()

Returns an enumeration of the jar file entries.

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 the jar file entries. Entries appear in the Stream in the order they appear in the central directory of the jar file.

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

versionedStream

public Stream<JarEntry> versionedStream()

Returns a Stream of the versioned jar file entries.

If this JarFile is a multi-release jar file and is configured to be processed as such, then an entry in the stream is the latest versioned entry associated with the corresponding base entry name. The maximum version of the latest versioned entry is the version returned by getVersion(). The returned stream may include an entry that only exists as a versioned entry. If the jar file is not a multi-release jar file or the JarFile is not configured for processing a multi-release jar file, this method returns the same stream that stream() returns.

Returns:: stream of versioned entries
Since:: 10

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
API Note:: The InputStream returned by this method can wrap an InflaterInputStream, whose read(byte[], int, int) method can modify any element of the output buffer.
Parameters:: ze - the ZIP file entry
Returns:: an input stream for reading the contents of the specified ZIP file entry or null if the ZIP file entry does not exist within the jar file
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

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