org.eclipse.gemini.blueprint.context.support.internal.classloader

Class ChainedClassLoader

java.lang.Object

java.lang.ClassLoader

org.eclipse.gemini.blueprint.context.support.internal.classloader.ChainedClassLoader

public class ChainedClassLoader
extends java.lang.ClassLoader

Chaining class loader implementation that delegates the resource and class loading to a number of class loaders passed in.

This class loader parent (by default the AppClassLoader) can be specified and will be added automatically as the last entry in the list.

Additionally, the class space of this class loader can be extended at runtime (by allowing more class loaders to be added). Note:non-OSGi class loaders are considered as special cases. As there are classes that are loaded by the Boot, Ext, App and Fwk ClassLoaders through boot delegation, this implementation tries to identify them and place them last in the chain. Otherwise, these loaders can pull in classes from outside OSGi causing ClassCastExceptions.

Field Summary

Fields

Modifier and Type	Field and Description
private java.util.List<java.lang.ClassLoader>	loaders list of loaders
private java.util.List<java.lang.ClassLoader>	nonOsgiLoaders list of special, non-osgi loaders, added by the user
private java.lang.ClassLoader	parent parent class loader

Constructor Summary

Constructors

Constructor and Description
ChainedClassLoader(java.lang.ClassLoader[] loaders) Constructs a new ChainedClassLoader instance.
ChainedClassLoader(java.lang.ClassLoader[] loaders, java.lang.ClassLoader parent) Constructs a new ChainedClassLoader instance.

Method Summary

Modifier and Type	Method and Description
void	addClassLoader(java.lang.Class<?> clazz) Adds a class loader defining the given class, to the chained class loader space.
void	addClassLoader(java.lang.ClassLoader classLoader) Adds the given class loader to the existing list.
private boolean	addNonOsgiLoader(java.lang.ClassLoader classLoader) Checks if the given classloader is a known, non-OSGi loader.
private void	addOsgiLoader(java.lang.ClassLoader classLoader)
private java.net.URL	doGetResource(java.lang.String name)
private java.net.URL	doGetResource(java.lang.String name, java.util.List<java.lang.ClassLoader> classLoaders)
private java.lang.Class<?>	doLoadClass(java.lang.String name)
private java.lang.Class<?>	doLoadClass(java.lang.String name, java.util.List<java.lang.ClassLoader> classLoaders)
java.net.URL	getResource(java.lang.String name)
java.lang.Class<?>	loadClass(java.lang.String name)

Methods inherited from class java.lang.ClassLoader

clearAssertionStatus, defineClass, defineClass, defineClass, defineClass, definePackage, findClass, findLibrary, findLoadedClass, findResource, findResources, findSystemClass, getClassLoadingLock, getPackage, getPackages, getParent, getResourceAsStream, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, loadClass, registerAsParallelCapable, resolveClass, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus, setSigners

Methods inherited from class java.lang.Object

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

Field Detail

loaders

private final java.util.List<java.lang.ClassLoader> loaders

list of loaders

nonOsgiLoaders

private final java.util.List<java.lang.ClassLoader> nonOsgiLoaders

list of special, non-osgi loaders, added by the user

parent

private final java.lang.ClassLoader parent

parent class loader

Constructor Detail

ChainedClassLoader

public ChainedClassLoader(java.lang.ClassLoader[] loaders)

Constructs a new ChainedClassLoader instance. Equivalent to ChainedClassLoader(ClassLoader[], ClassLoader) with the parent class loader initialized to the AppClassLoader (practically the system bundle class loader). Note that the AppClassLoader can be different then the ClassLoader.getSystemClassLoader(), used by ChainedClassLoader(ClassLoader[], ClassLoader) if no parent is specified.

Parameters:

loaders - array of non-null class loaders

ChainedClassLoader

public ChainedClassLoader(java.lang.ClassLoader[] loaders,
                          java.lang.ClassLoader parent)

Constructs a new ChainedClassLoader instance.

Parameters:

loaders - array of non-null class loaders

parent - parent class loader (can be null)

Method Detail

getResource

public java.net.URL getResource(java.lang.String name)

Overrides:

getResource in class java.lang.ClassLoader

doGetResource

private java.net.URL doGetResource(java.lang.String name)

doGetResource

private java.net.URL doGetResource(java.lang.String name,
                                   java.util.List<java.lang.ClassLoader> classLoaders)

loadClass

public java.lang.Class<?> loadClass(java.lang.String name)
                             throws java.lang.ClassNotFoundException

Overrides:

loadClass in class java.lang.ClassLoader

Throws:

java.lang.ClassNotFoundException

doLoadClass

private java.lang.Class<?> doLoadClass(java.lang.String name)
                                throws java.lang.ClassNotFoundException

Throws:

java.lang.ClassNotFoundException

doLoadClass

private java.lang.Class<?> doLoadClass(java.lang.String name,
                                       java.util.List<java.lang.ClassLoader> classLoaders)
                                throws java.lang.ClassNotFoundException

Throws:

java.lang.ClassNotFoundException

addClassLoader

public void addClassLoader(java.lang.Class<?> clazz)

Adds a class loader defining the given class, to the chained class loader space.

Parameters:

clazz -

addClassLoader

public void addClassLoader(java.lang.ClassLoader classLoader)

Adds the given class loader to the existing list.

Parameters:

classLoader - class loader to load classes from

addNonOsgiLoader

private boolean addNonOsgiLoader(java.lang.ClassLoader classLoader)

Checks if the given classloader is a known, non-OSGi loader. If it is, then it is added to a specific list based on the known ordering (ignoring the user defined one). This is done so that the discovered hierarchy is respected regardless of the user configuration.

Parameters:

classLoader -

Returns:

true if the class loader was added/is known, false otherwise

addOsgiLoader

private void addOsgiLoader(java.lang.ClassLoader classLoader)