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, 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:

  • Field Summary

    Fields
    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 java.util.zip.ZipFile

    OPEN_DELETE, OPEN_READ

  • Constructor Summary

    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.

  • 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 java.util.zip.ZipFile

    close, getComment, getName, size

    Methods declared in class java.lang.Object

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

  • 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
      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

  • 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
      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