Java Doc for JarURLConnection.java in  » 6.0-JDK-Modules » j2me » java » net » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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();
 

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

NOTE: In J2ME CDC, there is no support for certificates by design. If CDC by itself or a J2ME profile built on CDC does not add back the java.security.Signature class (plus all its dependencies), a null value must always be returned. the Certificate object for this connection if the URLfor it points to a JAR file entry, null otherwise.
exception:
  IOException - if getting the JAR entry causes anIOException to be thrown.
See Also:   JarURLConnection.getJarEntry