# 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:
  - `Manifest`
  - `ZipFile`
  - `JarEntry`

- ## 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, toString`

  ### Methods declared in class java.lang.Object

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

- ## Field Details

  - ### MANIFEST_NAME

    public static final String MANIFEST_NAME
    The JAR manifest file name.
    See Also:
      - Constant Field Values

  - ### LOCSIG

    static final long LOCSIG
    Local file (LOC) header signature.
    See Also:
      - Constant Field Values

  - ### EXTSIG

    static final long EXTSIG
    Extra local (EXT) header signature.
    See Also:
      - Constant Field Values

  - ### CENSIG

    static final long CENSIG
    Central directory (CEN) header signature.
    See Also:
      - Constant Field Values

  - ### ENDSIG

    static final long ENDSIG
    End of central directory (END) header signature.
    See Also:
      - Constant Field Values

  - ### LOCHDR

    static final int LOCHDR
    Local file (LOC) header size in bytes (including signature).
    See Also:
      - Constant Field Values

  - ### EXTHDR

    static final int EXTHDR
    Extra local (EXT) header size in bytes (including signature).
    See Also:
      - Constant Field Values

  - ### CENHDR

    static final int CENHDR
    Central directory (CEN) header size in bytes (including signature).
    See Also:
      - Constant Field Values

  - ### ENDHDR

    static final int ENDHDR
    End of central directory (END) header size in bytes (including signature).
    See Also:
      - Constant Field Values

  - ### LOCVER

    static final int LOCVER
    Local file (LOC) header version needed to extract field offset.
    See Also:
      - Constant Field Values

  - ### LOCFLG

    static final int LOCFLG
    Local file (LOC) header general purpose bit flag field offset.
    See Also:
      - Constant Field Values

  - ### LOCHOW

    static final int LOCHOW
    Local file (LOC) header compression method field offset.
    See Also:
      - Constant Field Values

  - ### LOCTIM

    static final int LOCTIM
    Local file (LOC) header modification time field offset.
    See Also:
      - Constant Field Values

  - ### LOCCRC

    static final int LOCCRC
    Local file (LOC) header uncompressed file crc-32 value field offset.
    See Also:
      - Constant Field Values

  - ### LOCSIZ

    static final int LOCSIZ
    Local file (LOC) header compressed size field offset.
    See Also:
      - Constant Field Values

  - ### LOCLEN

    static final int LOCLEN
    Local file (LOC) header uncompressed size field offset.
    See Also:
      - Constant Field Values

  - ### LOCNAM

    static final int LOCNAM
    Local file (LOC) header filename length field offset.
    See Also:
      - Constant Field Values

  - ### LOCEXT

    static final int LOCEXT
    Local file (LOC) header extra field length field offset.
    See Also:
      - Constant Field Values

  - ### EXTCRC

    static final int EXTCRC
    Extra local (EXT) header uncompressed file crc-32 value field offset.
    See Also:
      - Constant Field Values

  - ### EXTSIZ

    static final int EXTSIZ
    Extra local (EXT) header compressed size field offset.
    See Also:
      - Constant Field Values

  - ### EXTLEN

    static final int EXTLEN
    Extra local (EXT) header uncompressed size field offset.
    See Also:
      - Constant Field Values

  - ### CENVEM

    static final int CENVEM
    Central directory (CEN) header version made by field offset.
    See Also:
      - Constant Field Values

  - ### CENVER

    static final int CENVER
    Central directory (CEN) header version needed to extract field offset.
    See Also:
      - Constant Field Values

  - ### CENFLG

    static final int CENFLG
    Central directory (CEN) header encrypt, decrypt flags field offset.
    See Also:
      - Constant Field Values

  - ### CENHOW

    static final int CENHOW
    Central directory (CEN) header compression method field offset.
    See Also:
      - Constant Field Values

  - ### CENTIM

    static final int CENTIM
    Central directory (CEN) header modification time field offset.
    See Also:
      - Constant Field Values

  - ### CENCRC

    static final int CENCRC
    Central directory (CEN) header uncompressed file crc-32 value field offset.
    See Also:
      - Constant Field Values

  - ### CENSIZ

    static final int CENSIZ
    Central directory (CEN) header compressed size field offset.
    See Also:
      - Constant Field Values

  - ### CENLEN

    static final int CENLEN
    Central directory (CEN) header uncompressed size field offset.
    See Also:
      - Constant Field Values

  - ### CENNAM

    static final int CENNAM
    Central directory (CEN) header filename length field offset.
    See Also:
      - Constant Field Values

  - ### CENEXT

    static final int CENEXT
    Central directory (CEN) header extra field length field offset.
    See Also:
      - Constant Field Values

  - ### CENCOM

    static final int CENCOM
    Central directory (CEN) header comment length field offset.
    See Also:
      - Constant Field Values

  - ### CENDSK

    static final int CENDSK
    Central directory (CEN) header disk number start field offset.
    See Also:
      - Constant Field Values

  - ### CENATT

    static final int CENATT
    Central directory (CEN) header internal file attributes field offset.
    See Also:
      - Constant Field Values

  - ### CENATX

    static final int CENATX
    Central directory (CEN) header external file attributes field offset.
    See Also:
      - Constant Field Values

  - ### CENOFF

    static final int CENOFF
    Central directory (CEN) header LOC header offset field offset.
    See Also:
      - Constant Field Values

  - ### ENDSUB

    static final int ENDSUB
    End of central directory (END) header number of entries on this disk field offset.
    See Also:
      - Constant Field Values

  - ### ENDTOT

    static final int ENDTOT
    End of central directory (END) header total number of entries field offset.
    See Also:
      - Constant Field Values

  - ### ENDSIZ

    static final int ENDSIZ
    End of central directory (END) header central directory size in bytes field offset.
    See Also:
      - Constant Field Values

  - ### ENDOFF

    static final int ENDOFF
    End of central directory (END) header offset for the first CEN header field offset.
    See Also:
      - Constant Field Values

  - ### ENDCOM

    static final int ENDCOM
    End of central directory (END) header ZIP file comment length field offset.
    See Also:
      - Constant Field Values

- ## 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:
      - `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`
    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