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 verfieid 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:

Manifest, ZipFile, JarEntry

Fields

Modifier and Type	Field	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 declared in class java.util.zip.ZipFile

OPEN_DELETE, OPEN_READ

Constructors

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`.

Methods

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.
`Runtime.Version`	`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.
`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 java.util.zip.ZipFile

close, finalize, getComment, getName, size

Methods declared in class java.lang.Object

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

Fields

MANIFEST_NAME

public static final String MANIFEST_NAME

The JAR manifest file name.

See Also:: Constant Field Values

LOCSIG

public static final long LOCSIG

See Also:: Constant Field Values

EXTSIG

public static final long EXTSIG

See Also:: Constant Field Values

CENSIG

public static final long CENSIG

See Also:: Constant Field Values

ENDSIG

public static final long ENDSIG

See Also:: Constant Field Values

LOCHDR

public static final int LOCHDR

See Also:: Constant Field Values

EXTHDR

public static final int EXTHDR

See Also:: Constant Field Values

CENHDR

public static final int CENHDR

See Also:: Constant Field Values

ENDHDR

public static final int ENDHDR

See Also:: Constant Field Values

LOCVER

public static final int LOCVER

See Also:: Constant Field Values

LOCFLG

public static final int LOCFLG

See Also:: Constant Field Values

LOCHOW

public static final int LOCHOW

See Also:: Constant Field Values

LOCTIM

public static final int LOCTIM

See Also:: Constant Field Values

LOCCRC

public static final int LOCCRC

See Also:: Constant Field Values

LOCSIZ

public static final int LOCSIZ

See Also:: Constant Field Values

LOCLEN

public static final int LOCLEN

See Also:: Constant Field Values

LOCNAM

public static final int LOCNAM

See Also:: Constant Field Values

LOCEXT

public static final int LOCEXT

See Also:: Constant Field Values

EXTCRC

public static final int EXTCRC

See Also:: Constant Field Values

EXTSIZ

public static final int EXTSIZ

See Also:: Constant Field Values

EXTLEN

public static final int EXTLEN

See Also:: Constant Field Values

CENVEM

public static final int CENVEM

See Also:: Constant Field Values

CENVER

public static final int CENVER

See Also:: Constant Field Values

CENFLG

public static final int CENFLG

See Also:: Constant Field Values

CENHOW

public static final int CENHOW

See Also:: Constant Field Values

CENTIM

public static final int CENTIM

See Also:: Constant Field Values

CENCRC

public static final int CENCRC

See Also:: Constant Field Values

CENSIZ

public static final int CENSIZ

See Also:: Constant Field Values

CENLEN

public static final int CENLEN

See Also:: Constant Field Values

CENNAM

public static final int CENNAM

See Also:: Constant Field Values

CENEXT

public static final int CENEXT

See Also:: Constant Field Values

CENCOM

public static final int CENCOM

See Also:: Constant Field Values

CENDSK

public static final int CENDSK

See Also:: Constant Field Values

CENATT

public static final int CENATT

See Also:: Constant Field Values

CENATX

public static final int CENATX

See Also:: Constant Field Values

CENOFF

public static final int CENOFF

See Also:: Constant Field Values

ENDSUB

public static final int ENDSUB

See Also:: Constant Field Values

ENDTOT

public static final int ENDTOT

See Also:: Constant Field Values

ENDSIZ

public static final int ENDSIZ

See Also:: Constant Field Values

ENDOFF

public static final int ENDOFF

See Also:: Constant Field Values

ENDCOM

public static final int ENDCOM

See Also:: Constant Field Values

Constructors

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

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,
               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; SecurityException - if access to the file is denied by the SecurityManager; NullPointerException - if version is null
Since:: 9

Methods

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:: 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.

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
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

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https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/jar/JarFile.html