Class JarInputStream

All Implemented Interfaces:
Closeable, AutoCloseable
public class JarInputStream
extends ZipInputStream

The JarInputStream class is used to read the contents of a JAR file from any input stream. It extends the class java.util.zip.ZipInputStream with support for reading an optional Manifest entry. The Manifest can be used to store meta-information about the JAR file and its entries.

Since:
1.2
See Also:
Manifest, ZipInputStream

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

Fields declared in class java.util.zip.InflaterInputStream

buf, inf, len

Fields declared in class java.io.FilterInputStream

in

Constructors

Constructor Description
JarInputStream​(InputStream in)

Creates a new JarInputStream and reads the optional manifest.

JarInputStream​(InputStream in, boolean verify)

Creates a new JarInputStream and reads the optional manifest.

Methods

Modifier and Type Method Description
protected ZipEntry createZipEntry​(String name)

Creates a new JarEntry (ZipEntry) for the specified JAR file entry name.

Manifest getManifest()

Returns the Manifest for this JAR file, or null if none.

ZipEntry getNextEntry()

Reads the next ZIP file entry and positions the stream at the beginning of the entry data.

JarEntry getNextJarEntry()

Reads the next JAR file entry and positions the stream at the beginning of the entry data.

int read​(byte[] b, int off, int len)

Reads from the current JAR file entry into an array of bytes.

Methods declared in class java.util.zip.ZipInputStream

available, close, closeEntry, skip

Methods declared in class java.util.zip.InflaterInputStream

fill, mark, markSupported, read, reset

Methods declared in class java.io.FilterInputStream

read

Methods declared in class java.io.InputStream

nullInputStream, readAllBytes, readNBytes, readNBytes, transferTo

Methods declared in class java.lang.Object

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

Fields

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

JarInputStream

public JarInputStream(InputStream in)
               throws IOException

Creates a new JarInputStream and reads the optional manifest. If a manifest is present, also attempts to verify the signatures if the JarInputStream is signed.

Parameters:
in - the actual input stream
Throws:
IOException - if an I/O error has occurred

JarInputStream

public JarInputStream(InputStream in,
                      boolean verify)
               throws IOException

Creates a new JarInputStream and reads the optional manifest. If a manifest is present and verify is true, also attempts to verify the signatures if the JarInputStream is signed.

Parameters:
in - the actual input stream
verify - whether or not to verify the JarInputStream if it is signed.
Throws:
IOException - if an I/O error has occurred

Methods

getManifest

public Manifest getManifest()

Returns the Manifest for this JAR file, or null if none.

Returns:
the Manifest for this JAR file, or null if none.

getNextEntry

public ZipEntry getNextEntry()
                      throws IOException

Reads the next ZIP file entry and positions the stream at the beginning of the entry data. If verification has been enabled, any invalid signature detected while positioning the stream for the next entry will result in an exception.

Overrides:
getNextEntry in class ZipInputStream
Returns:
the next ZIP file entry, or null if there are no more entries
Throws:
ZipException - if a ZIP file error has occurred
IOException - if an I/O error has occurred
SecurityException - if any of the jar file entries are incorrectly signed.

getNextJarEntry

public JarEntry getNextJarEntry()
                         throws IOException

Reads the next JAR file entry and positions the stream at the beginning of the entry data. If verification has been enabled, any invalid signature detected while positioning the stream for the next entry will result in an exception.

Returns:
the next JAR file entry, or null if there are no more entries
Throws:
ZipException - if a ZIP file error has occurred
IOException - if an I/O error has occurred
SecurityException - if any of the jar file entries are incorrectly signed.

read

public int read(byte[] b,
                int off,
                int len)
         throws IOException

Reads from the current JAR file entry into an array of bytes. If len is not zero, the method blocks until some input is available; otherwise, no bytes are read and 0 is returned. If verification has been enabled, any invalid signature on the current entry will be reported at some point before the end of the entry is reached.

Overrides:
read in class ZipInputStream
Parameters:
b - the buffer into which the data is read
off - the start offset in the destination array b
len - the maximum number of bytes to read
Returns:
the actual number of bytes read, or -1 if the end of the entry is reached
Throws:
NullPointerException - If b is null.
IndexOutOfBoundsException - If off is negative, len is negative, or len is greater than b.length - off
ZipException - if a ZIP file error has occurred
IOException - if an I/O error has occurred
SecurityException - if any of the jar file entries are incorrectly signed.
See Also:
FilterInputStream.in

createZipEntry

protected ZipEntry createZipEntry(String name)

Creates a new JarEntry (ZipEntry) for the specified JAR file entry name. The manifest attributes of the specified JAR file entry name will be copied to the new JarEntry.

Overrides:
createZipEntry in class ZipInputStream
Parameters:
name - the name of the JAR/ZIP file entry
Returns:
the JarEntry object just created

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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/jar/JarInputStream.html