net.sourceforge.groboutils.util.classes.v1.jdk0
Class UrlClassLoader

java.lang.Object
  net.sourceforge.groboutils.util.classes.v1.jdk0.UrlClassLoader

All Implemented Interfaces:

BytecodeSource, IUrlClassLoader

public class UrlClassLoader

extends java.lang.Object

implements IUrlClassLoader, BytecodeSource

Class responsible for loading classes in a JDK 1.0+ version compatible way. Need to determine speed vs. size for caching Jar files that are loaded over the internet. For now, we cache stuff, in the hope that the flush() will be called.

If the URL is null, or if the bytecode for a class name is not found, then this will attempt to load the class from the system classloader.

NOTE: As of version 1.0.0, there is no longer a dependency upon net.sourceforge.groboutils.util.io.v1

Since:

November 17, 2000 (GroboUtils Alpha 0.9.0)

Version:

$Date: 2003/05/06 05:35:00 $

Author:

Matt Albrecht groboclown@users.sourceforge.net

Constructor Summary

UrlClassLoader()
Default constructor

Method Summary

protected java.lang.String	className2jarFileName(java.lang.String className) Converts a class name to a file name.
protected java.lang.String	convertUrl(java.lang.String url) Converts the given string to a fully qualified URL.
protected byte[]	findZipEntry(java.lang.String filename, java.util.zip.ZipInputStream zis) Finds the entry of the given filename in the given input stream, and returns the entry as a byte array.
void	flush() Call to flush any cache stored in the interface.
protected java.lang.String	getAbsoluteFilename(java.io.File f)
byte[]	getBytecode(java.lang.String classname) Loads the bytecode for the given classname.
protected BytecodeSource	getBytecodeSource(java.lang.String url)
protected boolean	isJarURL(java.lang.String url)
protected java.lang.String	joinClassToUrl(java.lang.String className, java.lang.String url) Joins a classname to a URL.
java.lang.Class	loadClass(java.lang.String className, java.lang.String url) Load the given class from the given URL.
protected byte[]	readByteStream(java.io.InputStream is) A re-implementation of net.groboclown.util.io.v1.ReadByteStream, to reduce the amount of inter-package dependencies.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

UrlClassLoader

public UrlClassLoader()

Default constructor

Method Detail

loadClass

public java.lang.Class loadClass(java.lang.String className,
                                 java.lang.String url)

Load the given class from the given URL. If the URL is null, then it loads the class from the default class loader.

Specified by:

loadClass in interface IUrlClassLoader

Parameters:

className - the exact class name to load.

url - the URL from which the class is loaded. If this is null, then this loads the class from the default class loader.

Returns:

the loaded Class instance, or null if the class could not be found.

flush

public void flush()

Call to flush any cache stored in the interface. This allows for a class loader to cache results, and free up memory when it is not needed.

Specified by:

flush in interface IUrlClassLoader

getBytecode

public byte[] getBytecode(java.lang.String classname)

Description copied from interface: BytecodeSource

Loads the bytecode for the given classname.

Specified by:

getBytecode in interface BytecodeSource

Parameters:

classname - the name of the class to find.

Returns:

null if there was an error finding the class, or the bytecode for the given class.

getBytecodeSource

protected BytecodeSource getBytecodeSource(java.lang.String url)

convertUrl

protected java.lang.String convertUrl(java.lang.String url)

Converts the given string to a fully qualified URL. If no scheme is given, then it is converted to a File scheme.

isJarURL

protected boolean isJarURL(java.lang.String url)

Returns:

true if the URL references a Jar-like file.

findZipEntry

protected byte[] findZipEntry(java.lang.String filename,
                              java.util.zip.ZipInputStream zis)

Finds the entry of the given filename in the given input stream, and returns the entry as a byte array. If the entry wasn't found, then null is returned.

className2jarFileName

protected java.lang.String className2jarFileName(java.lang.String className)

Converts a class name to a file name.

joinClassToUrl

protected java.lang.String joinClassToUrl(java.lang.String className,
                                          java.lang.String url)

Joins a classname to a URL.

getAbsoluteFilename

protected java.lang.String getAbsoluteFilename(java.io.File f)

readByteStream

protected byte[] readByteStream(java.io.InputStream is)
                         throws java.io.IOException

A re-implementation of net.groboclown.util.io.v1.ReadByteStream, to reduce the amount of inter-package dependencies.

Throws:

java.io.IOException