Class JarInputStream

java.util.jar.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:

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.

Fields declared in class java.util.zip.InflaterInputStream

buf, inf, len

Fields declared in class java.io.FilterInputStream

in

Constructor Summary

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.

Method Summary

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, skipNBytes, transferTo

Methods declared in class java.lang.Object

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

Field Details

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

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

Method Details

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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https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/jar/JarInputStream.html