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JarURLConnection.javaAPI DocJava SE 5 API8647Fri Aug 26 14:57:08 BST 2005java.net

JarURLConnection

public abstract class JarURLConnection extends URLConnection
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 {@link java.io.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
java.net.URL
see
java.net.URLConnection
see
java.util.jar.JarFile
see
java.util.jar.JarInputStream
see
java.util.jar.Manifest
see
java.util.zip.ZipEntry
author
Benjamin Renaud
since
1.2

Fields Summary
private URL
jarFileURL
private String
entryName
protected URLConnection
jarFileURLConnection
The connection to the JAR file URL, if the connection has been initiated. This should be set by connect.
Constructors Summary
protected JarURLConnection(URL url)
Creates the new JarURLConnection to the specified URL.

param
url the URL
throws
MalformedURLException if no legal protocol could be found in a specification string or the string could not be parsed.

	super(url);
	parseSpecs(url);
    
Methods Summary
public java.util.jar.AttributesgetAttributes()
Return the Attributes object for this connection if the URL for it points to a JAR file entry, null otherwise.

return
the Attributes object for this connection if the URL for it points to a JAR file entry, null otherwise.
exception
IOException if getting the JAR entry causes an IOException to be thrown.
see
#getJarEntry

	JarEntry e = getJarEntry();
	return e != null ? e.getAttributes() : null;
    
public java.security.cert.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

return
the Certificate object for this connection if the URL for it points to a JAR file entry, null otherwise.
exception
IOException if getting the JAR entry causes an IOException to be thrown.
see
#getJarEntry

	JarEntry e = getJarEntry();
	return e != null ? e.getCertificates() : null;
    
public java.lang.StringgetEntryName()
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.

return
the entry name for this connection, if any.

	return entryName;
    
public java.util.jar.JarEntrygetJarEntry()
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.

return
the JAR entry object for this connection, or null if the JAR URL for this connection points to a JAR file.
exception
IOException if getting the JAR file for this connection causes an IOException to be trown.
see
#getJarFile
see
#getJarEntry

	return getJarFile().getJarEntry(entryName);
    
public abstract java.util.jar.JarFilegetJarFile()
Return the JAR file for this connection.

return
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
exception
IOException if an IOException occurs while trying to connect to the JAR file for this connection.
see
#connect

public java.net.URLgetJarFileURL()
Returns the URL for the Jar file for this connection.

return
the URL for the Jar file for this connection.

	return jarFileURL;
    
public java.util.jar.AttributesgetMainAttributes()
Returns the main Attributes for the JAR file for this connection.

return
the main Attributes for the JAR file for this connection.
exception
IOException if getting the manifest causes an IOException to be thrown.
see
#getJarFile
see
#getManifest

 
	Manifest man = getManifest();
	return man != null ? man.getMainAttributes() : null;
    
public java.util.jar.ManifestgetManifest()
Returns the Manifest for this connection, or null if none.

return
the manifest object corresponding to the JAR file object for this connection.
exception
IOException if getting the JAR file for this connection causes an IOException to be trown.
see
#getJarFile

	return getJarFile().getManifest();
    
private voidparseSpecs(java.net.URL url)

	String spec = url.getFile();

	int separator = spec.indexOf('!");
	/*
	 * REMIND: we don't handle nested JAR URLs
	 */
	if (separator == -1) {
	    throw new MalformedURLException("no ! found in url spec:" + spec);
	}

	jarFileURL = new URL(spec.substring(0, separator++));
	entryName = null;

	/* if ! is the last letter of the innerURL, entryName is null */
	if (++separator != spec.length()) {
	    entryName = spec.substring(separator, spec.length());
	    entryName = ParseUtil.decode (entryName);
	}