Class JarInputStream

• java.lang.Object
• • java.io.InputStream
  • • java.io.FilterInputStream
    • • java.util.zip.InflaterInputStream
      • • java.util.zip.ZipInputStream
        • • 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:

Manifest, ZipInputStream

Fields

LOCSIG

public static final long LOCSIG

EXTSIG

public static final long EXTSIG

CENSIG

public static final long CENSIG

ENDSIG

public static final long ENDSIG

LOCHDR

public static final int LOCHDR

EXTHDR

public static final int EXTHDR

CENHDR

public static final int CENHDR

ENDHDR

public static final int ENDHDR

LOCVER

public static final int LOCVER

LOCFLG

public static final int LOCFLG

LOCHOW

public static final int LOCHOW

LOCTIM

public static final int LOCTIM

LOCCRC

public static final int LOCCRC

LOCSIZ

public static final int LOCSIZ

LOCLEN

public static final int LOCLEN

LOCNAM

public static final int LOCNAM

LOCEXT

public static final int LOCEXT

EXTCRC

public static final int EXTCRC

EXTSIZ

public static final int EXTSIZ

EXTLEN

public static final int EXTLEN

CENVEM

public static final int CENVEM

CENVER

public static final int CENVER

CENFLG

public static final int CENFLG

CENHOW

public static final int CENHOW

CENTIM

public static final int CENTIM

CENCRC

public static final int CENCRC

CENSIZ

public static final int CENSIZ

CENLEN

public static final int CENLEN

CENNAM

public static final int CENNAM

CENEXT

public static final int CENEXT

CENCOM

public static final int CENCOM

CENDSK

public static final int CENDSK

CENATT

public static final int CENATT

CENATX

public static final int CENATX

CENOFF

public static final int CENOFF

ENDSUB

public static final int ENDSUB

ENDTOT

public static final int ENDTOT

ENDSIZ

public static final int ENDSIZ

ENDOFF

public static final int ENDOFF

ENDCOM

public static final int ENDCOM

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