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JarURLConnection

public abstract class JarURLConnection
extends URLConnection

java.lang.Object
   ↳ java.net.URLConnection
     ↳ java.net.JarURLConnection


A URL Connection to a Java ARchive (JAR) file or an entry in a JAR file.

The syntax of a JAR URL is:

 jar:<url>!/{entry}
 

for example:

jar:http://www.foo.com/bar/baz.jar!/COM/foo/Quux.class

Jar URLs should be used to refer to a JAR file or entries in a JAR file. The example above is a JAR URL which refers to a JAR entry. If the entry name is omitted, the URL refers to the whole JAR file: jar:http://www.foo.com/bar/baz.jar!/

Users should cast the generic URLConnection to a JarURLConnection when they know that the URL they created is a JAR URL, and they need JAR-specific functionality. For example:

 URL url = new URL("jar:file:/home/duke/duke.jar!/");
 JarURLConnection jarConnection = (JarURLConnection)url.openConnection();
 Manifest manifest = jarConnection.getManifest();
 

JarURLConnection instances can only be used to read from JAR files. It is not possible to get a OutputStream to modify or write to the underlying JAR file using this class.

Examples:

A Jar entry
jar:http://www.foo.com/bar/baz.jar!/COM/foo/Quux.class
A Jar file
jar:http://www.foo.com/bar/baz.jar!/
A Jar directory
jar:http://www.foo.com/bar/baz.jar!/COM/foo/

!/ is refered to as the separator.

When constructing a JAR url via new URL(context, spec), the following rules apply:

  • if there is no context URL and the specification passed to the URL constructor doesn't contain a separator, the URL is considered to refer to a JarFile.
  • if there is a context URL, the context URL is assumed to refer to a JAR file or a Jar directory.
  • if the specification begins with a '/', the Jar directory is ignored, and the spec is considered to be at the root of the Jar file.

    Examples:

    context: jar:http://www.foo.com/bar/jar.jar!/, spec:baz/entry.txt
    url:jar:http://www.foo.com/bar/jar.jar!/baz/entry.txt
    context: jar:http://www.foo.com/bar/jar.jar!/baz, spec:entry.txt
    url:jar:http://www.foo.com/bar/jar.jar!/baz/entry.txt
    context: jar:http://www.foo.com/bar/jar.jar!/baz, spec:/entry.txt
    url:jar:http://www.foo.com/bar/jar.jar!/entry.txt

See also:

Summary

Fields

protected URLConnection jarFileURLConnection

The connection to the JAR file URL, if the connection has been initiated.

Inherited fields

From class java.net.URLConnection

Protected constructors

JarURLConnection(URL url)

Creates the new JarURLConnection to the specified URL.

Public methods

Attributes getAttributes()

Return the Attributes object for this connection if the URL for it points to a JAR file entry, null otherwise.

Certificate[] getCertificates()

Return the Certificate object for this connection if the URL for it points to a JAR file entry, null otherwise.

String getEntryName()

Return the entry name for this connection.

JarEntry getJarEntry()

Return the JAR entry object for this connection, if any.

abstract JarFile getJarFile()

Return the JAR file for this connection.

URL getJarFileURL()

Returns the URL for the Jar file for this connection.

Attributes getMainAttributes()

Returns the main Attributes for the JAR file for this connection.

Manifest getManifest()

Returns the Manifest for this connection, or null if none.

Inherited methods

From class java.net.URLConnection
From class java.lang.Object

Fields

jarFileURLConnection

Added in API level 1
URLConnection jarFileURLConnection

The connection to the JAR file URL, if the connection has been initiated. This should be set by connect.

Protected constructors

JarURLConnection

Added in API level 1
JarURLConnection (URL url)

Creates the new JarURLConnection to the specified URL.

Parameters
url URL: the URL
Throws
MalformedURLException if no legal protocol could be found in a specification string or the string could not be parsed.

Public methods

getAttributes

Added in API level 1
Attributes getAttributes ()

Return the Attributes object for this connection if the URL for it points to a JAR file entry, null otherwise.

Returns
Attributes the Attributes object for this connection if the URL for it points to a JAR file entry, null otherwise.
Throws
IOException if getting the JAR entry causes an IOException to be thrown.

See also:

getCertificates

Added in API level 1
Certificate[] getCertificates ()

Return the Certificate object for this connection if the URL for it points to a JAR file entry, null otherwise. This method can only be called once the connection has been completely verified by reading from the input stream until the end of the stream has been reached. Otherwise, this method will return null

Returns
Certificate[] the Certificate object for this connection if the URL for it points to a JAR file entry, null otherwise.
Throws
IOException if getting the JAR entry causes an IOException to be thrown.

See also:

getEntryName

Added in API level 1
String getEntryName ()

Return the entry name for this connection. This method returns null if the JAR file URL corresponding to this connection points to a JAR file and not a JAR file entry.

Returns
String the entry name for this connection, if any.

getJarEntry

Added in API level 1
JarEntry getJarEntry ()

Return the JAR entry object for this connection, if any. This method returns null if the JAR file URL corresponding to this connection points to a JAR file and not a JAR file entry.

Returns
JarEntry the JAR entry object for this connection, or null if the JAR URL for this connection points to a JAR file.
Throws
IOException if getting the JAR file for this connection causes an IOException to be trown.

See also:

getJarFile

Added in API level 1
JarFile getJarFile ()

Return the JAR file for this connection.

Returns
JarFile the JAR file for this connection. If the connection is a connection to an entry of a JAR file, the JAR file object is returned
Throws
IOException if an IOException occurs while trying to connect to the JAR file for this connection.

See also:

getJarFileURL

Added in API level 1
URL getJarFileURL ()

Returns the URL for the Jar file for this connection.

Returns
URL the URL for the Jar file for this connection.

getMainAttributes

Added in API level 1
Attributes getMainAttributes ()

Returns the main Attributes for the JAR file for this connection.

Returns
Attributes the main Attributes for the JAR file for this connection.
Throws
IOException if getting the manifest causes an IOException to be thrown.

See also:

getManifest

Added in API level 1
Manifest getManifest ()

Returns the Manifest for this connection, or null if none.

Returns
Manifest the manifest object corresponding to the JAR file object for this connection.
Throws
IOException if getting the JAR file for this connection causes an IOException to be trown.

See also:

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