Package org.glassfish.internal.api

Class DelegatingClassLoader

java.lang.Object

java.lang.ClassLoader

org.glassfish.internal.api.DelegatingClassLoader

public class DelegatingClassLoader
extends ClassLoader

This classloader has a list of classloaders called as delegates that it uses to find classes. All those delegates must have the same parent as this classloader in order to have a consistent class space. By consistent class space, I mean a class space where no two loaded class have same name. An inconsistent class space can lead to ClassCastException. This classloader does not define any class, classes are always loaded either by its parent or by one of the delegates.

Author:

Sanjeeb.Sahoo@Sun.COM

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	DelegatingClassLoader.ClassFinder	findClass method of ClassLoader is usually a protected method.

Constructor Summary

Constructors

Constructor	Description
DelegatingClassLoader(ClassLoader parent)
DelegatingClassLoader(ClassLoader parent, List<DelegatingClassLoader.ClassFinder> delegates)

Method Summary

Modifier and Type	Method	Description
boolean	addDelegate(DelegatingClassLoader.ClassFinder d)	Adds a ClassFinder to list of delegates.
Class<?>	findClass(String name)
protected URL	findResource(String name)
protected Enumeration<URL>	findResources(String name)
List<DelegatingClassLoader.ClassFinder>	getDelegates()
String	getName()
boolean	removeDelegate(DelegatingClassLoader.ClassFinder d)	Removes a ClassFinder from list of delegates.
void	setName(String name)
String	toString()

Methods inherited from class java.lang.ClassLoader

clearAssertionStatus, defineClass, defineClass, defineClass, defineClass, definePackage, findClass, findLibrary, findLoadedClass, findResource, findSystemClass, getClassLoadingLock, getDefinedPackage, getDefinedPackages, getPackage, getPackages, getParent, getPlatformClassLoader, getResource, getResourceAsStream, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, getUnnamedModule, isRegisteredAsParallelCapable, loadClass, loadClass, registerAsParallelCapable, resolveClass, resources, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus, setSigners

Methods inherited from class java.lang.Object

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

Constructor Details

DelegatingClassLoader

public DelegatingClassLoader(ClassLoader parent,
 List<DelegatingClassLoader.ClassFinder> delegates)
                      throws IllegalArgumentException

Throws:

IllegalArgumentException - when the delegate does not have same parent as this classloader.

DelegatingClassLoader

public DelegatingClassLoader(ClassLoader parent)

Method Details

addDelegate

public boolean addDelegate(DelegatingClassLoader.ClassFinder d)
                    throws IllegalStateException,
IllegalArgumentException

Adds a ClassFinder to list of delegates. To have a consistent class space (by consistent class space, I mean a classpace where there does not exist two class with same name), this method does not allow a delegate to be added that has a different parent.

Parameters:

d - ClassFinder to add to the list of delegates

Returns:

true if the delegate is added, false otherwise.

Throws:

IllegalStateException - when this method is called after the classloader has been used to load any class.

IllegalArgumentException - when the delegate does not have same parent as this classloader.

removeDelegate

public boolean removeDelegate(DelegatingClassLoader.ClassFinder d)

Removes a ClassFinder from list of delegates. This method must not be used once this classloader has beed used to load any class. If attempted to do so, this method throws IllegalStateException

Parameters:

d - ClassFinder to remove from the list of delegates

Returns:

true if the delegate was removed, false otherwise.

Throws:

IllegalStateException - when this method is called after the classloader has been used to load any class.

findClass

public Class<?> findClass(String name)
                   throws ClassNotFoundException

Overrides:

findClass in class ClassLoader

Throws:

ClassNotFoundException

findResource

protected URL findResource(String name)

Overrides:

findResource in class ClassLoader

findResources

protected Enumeration<URL> findResources(String name)
                                  throws IOException

Overrides:

findResources in class ClassLoader

Throws:

IOException

getName

public String getName()

Overrides:

getName in class ClassLoader

setName

public void setName(String name)

getDelegates

public List<DelegatingClassLoader.ClassFinder> getDelegates()

toString

public String toString()

Overrides:

toString in class Object