JarInputStream

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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.

Inherited Constant Summary

Inherited Field Summary

Public Constructor Summary

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 Method Summary

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 Method Summary

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

Inherited Method Summary

Public Constructors

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 the actual input stream
Throws
IOException if an I/O error has occurred

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 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

Public Methods

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.

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
  • 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.

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
  • 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.

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 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.

Protected Methods

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 the name of the JAR/ZIP file entry
Returns
  • the JarEntry object just created