Java in a Nutshell, 5th Edition [Electronic resources] نسخه متنی

This
class is a specialized URLConnection that
represents a connection to a jar: URL. A
jar: URL is a compound URL that includes the URL
of a JAR archive and, optionally, a reference to a file or directory
within the JAR archive. The jar: URL syntax uses
the ! character
to separate the pathname of the JAR archive from the
filename within the JAR archive. Note that a jar:
URL contains a subprotocol that specifies the protocol that retrieves
the JAR file itself. For example:

jar:http://my.jar.com/my.jar!/ // The whole archive
jar:file:/usr/java/lib/my.jar!/com/jar/ // A directory of the archive
jar:ftp://ftp.jar.com/pub/my.jar!/com/jar/Jar.class // A file in the archive

To obtain a JarURLConnection, define a
URL object for a jar: URL, open
a connection to it with openConnection( ), and
cast the returned URLConnection object to a
JarURLConnection. The various methods defined by
JarURLConnection allow you to read the manifest
file of the JAR archive and look up attributes from that manifest for
the archive as a whole or for individual entries in the archive.
These methods make use of various classes from the
java.util.jar package.

Figure 12-10. java.net.JarURLConnection

public abstract class

JarURLConnection extends URLConnection {
// Protected Constructors
protected

JarURLConnection (URL

url ) throws MalformedURLException;
// Public Instance Methods
public java.util.jar.Attributes

getAttributes ( ) throws java.io.IOException;
public java.security.cert.Certificate[ ]

getCertificates ( )
throws java.io.IOException;
public String

getEntryName ( );
public java.util.jar.JarEntry

getJarEntry ( ) throws java.io.IOException;
public abstract java.util.jar.JarFile

getJarFile ( )
throws java.io.IOException;
public URL

getJarFileURL ( );
public java.util.jar.Attributes

getMainAttributes ( )
throws java.io.IOException;
public java.util.jar.Manifest

getManifest ( ) throws java.io.IOException;
// Protected Instance Fields
protected URLConnection

jarFileURLConnection ;
}