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JarInputStream

public class JarInputStream
extends ZipInputStream

java.lang.Object
   ↳ java.io.InputStream
     ↳ java.io.FilterInputStream
       ↳ java.util.zip.InflaterInputStream
         ↳ java.util.zip.ZipInputStream
           ↳ java.util.jar.JarInputStream


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.

See also:

Summary

Constants

int CENATT

int CENATX

int CENCOM

int CENCRC

int CENDSK

int CENEXT

int CENFLG

int CENHDR

int CENHOW

int CENLEN

int CENNAM

int CENOFF

long CENSIG

int CENSIZ

int CENTIM

int CENVEM

int CENVER

int ENDCOM

int ENDHDR

int ENDOFF

long ENDSIG

int ENDSIZ

int ENDSUB

int ENDTOT

int EXTCRC

int EXTHDR

int EXTLEN

long EXTSIG

int EXTSIZ

int LOCCRC

int LOCEXT

int LOCFLG

int LOCHDR

int LOCHOW

int LOCLEN

int LOCNAM

long LOCSIG

int LOCSIZ

int LOCTIM

int LOCVER

Inherited constants

Inherited fields

Public constructors

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.

Public methods

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.

Protected methods

ZipEntry createZipEntry(String name)

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

Inherited methods

Constants

CENATT

public static final int CENATT

Constant Value: 36 (0x00000024)

CENATX

public static final int CENATX

Constant Value: 38 (0x00000026)

CENCOM

public static final int CENCOM

Constant Value: 32 (0x00000020)

CENCRC

public static final int CENCRC

Constant Value: 16 (0x00000010)

CENDSK

public static final int CENDSK

Constant Value: 34 (0x00000022)

CENEXT

public static final int CENEXT

Constant Value: 30 (0x0000001e)

CENFLG

public static final int CENFLG

Constant Value: 8 (0x00000008)

CENHDR

public static final int CENHDR

Constant Value: 46 (0x0000002e)

CENHOW

public static final int CENHOW

Constant Value: 10 (0x0000000a)

CENLEN

public static final int CENLEN

Constant Value: 24 (0x00000018)

CENNAM

public static final int CENNAM

Constant Value: 28 (0x0000001c)

CENOFF

public static final int CENOFF

Constant Value: 42 (0x0000002a)

CENSIG

public static final long CENSIG

Constant Value: 33639248 (0x0000000002014b50)

CENSIZ

public static final int CENSIZ

Constant Value: 20 (0x00000014)

CENTIM

public static final int CENTIM

Constant Value: 12 (0x0000000c)

CENVEM

public static final int CENVEM

Constant Value: 4 (0x00000004)

CENVER

public static final int CENVER

Constant Value: 6 (0x00000006)

ENDCOM

public static final int ENDCOM

Constant Value: 20 (0x00000014)

ENDHDR

public static final int ENDHDR

Constant Value: 22 (0x00000016)

ENDOFF

public static final int ENDOFF

Constant Value: 16 (0x00000010)

ENDSIG

public static final long ENDSIG

Constant Value: 101010256 (0x0000000006054b50)

ENDSIZ

public static final int ENDSIZ

Constant Value: 12 (0x0000000c)

ENDSUB

public static final int ENDSUB

Constant Value: 8 (0x00000008)

ENDTOT

public static final int ENDTOT

Constant Value: 10 (0x0000000a)

EXTCRC

public static final int EXTCRC

Constant Value: 4 (0x00000004)

EXTHDR

public static final int EXTHDR

Constant Value: 16 (0x00000010)

EXTLEN

public static final int EXTLEN

Constant Value: 12 (0x0000000c)

EXTSIG

public static final long EXTSIG

Constant Value: 134695760 (0x0000000008074b50)

EXTSIZ

public static final int EXTSIZ

Constant Value: 8 (0x00000008)

LOCCRC

public static final int LOCCRC

Constant Value: 14 (0x0000000e)

LOCEXT

public static final int LOCEXT

Constant Value: 28 (0x0000001c)

LOCFLG

public static final int LOCFLG

Constant Value: 6 (0x00000006)

LOCHDR

public static final int LOCHDR

Constant Value: 30 (0x0000001e)

LOCHOW

public static final int LOCHOW

Constant Value: 8 (0x00000008)

LOCLEN

public static final int LOCLEN

Constant Value: 22 (0x00000016)

LOCNAM

public static final int LOCNAM

Constant Value: 26 (0x0000001a)

LOCSIG

public static final long LOCSIG

Constant Value: 67324752 (0x0000000004034b50)

LOCSIZ

public static final int LOCSIZ

Constant Value: 18 (0x00000012)

LOCTIM

public static final int LOCTIM

Constant Value: 10 (0x0000000a)

LOCVER

public static final int LOCVER

Constant Value: 4 (0x00000004)

Public constructors

JarInputStream

public JarInputStream (InputStream in)

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 InputStream: the actual input stream

Throws
IOException if an I/O error has occurred

JarInputStream

public JarInputStream (InputStream in, 
                boolean verify)

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 InputStream: the actual input stream

verify boolean: whether or not to verify the JarInputStream if it is signed.

Throws
IOException if an I/O error has occurred

Public methods

getManifest

public Manifest getManifest ()

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

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

getNextEntry

public ZipEntry getNextEntry ()

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.

Returns
ZipEntry 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 ()

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
JarEntry 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)

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.

Parameters
b byte: the buffer into which the data is read

off int: the start offset in the destination array b

len int: the maximum number of bytes to read

Returns
int 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.

Protected methods

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.

Parameters
name String: the name of the JAR/ZIP file entry

Returns
ZipEntry the JarEntry object just created