org.jboss.mx.loading
Class UnifiedClassLoader

java.lang.Object
  java.lang.ClassLoader
      java.security.SecureClassLoader
          java.net.URLClassLoader
              org.jboss.mx.loading.UnifiedClassLoader

All Implemented Interfaces:

org.jboss.util.loading.Translatable, UnifiedClassLoaderMBean

Direct Known Subclasses:

UnifiedClassLoader2, UnifiedClassLoader3, UnifiedClassLoader4

public class UnifiedClassLoader

extends URLClassLoader

implements UnifiedClassLoaderMBean, org.jboss.util.loading.Translatable

A ClassLoader which loads classes from a single URL in conjunction with the LoaderRepository. Notice that this classloader does not work independently of the repository. A repository reference must be provided via the constructor or the classloader must be explicitly registered to the repository before any attempt to load a class. At this point this is little more than an abstract class maintained as the interface for class loaders as the algorithm of the UnifiedLoaderRepository fails with deadlocks, and several other class loading exceptions in multi- threaded environments.

Version:

$Revision: 1.9.4.28 $

Author:

Marc Fleury, Christoph G. Jung, Scott Stark, Juha Lindfors, Bill Burke

Field Summary

protected URL	origURL An optional URL from which url may have been copied.
protected LoaderRepository	repository Reference to the unified repository.
protected Exception	unregisterTrace The location where unregister is called from
protected URL	url One URL per ClassLoader in our case

Constructor Summary

UnifiedClassLoader(URL url)
Construct a UnifiedClassLoader without registering it to the classloader repository.

UnifiedClassLoader(URL url, LoaderRepository repository)
Construct a UnifiedClassLoader and registers it to the given repository.

UnifiedClassLoader(URL url, MBeanServer server, ObjectName repositoryName)
UnifiedClassLoader constructor that can be used to register with a particular Loader Repository identified by ObjectName.

UnifiedClassLoader(URL url, URL origURL)
Construct a UnifiedClassLoader without registering it to the classloader repository.

UnifiedClassLoader(URL url, URL origURL, ClassLoader parent)
Construct a UnifiedClassLoader without registering with the classloader repository.

UnifiedClassLoader(URL url, URL origURL, LoaderRepository repository)
Construct a UnifiedClassLoader and registers it to the given repository.

UnifiedClassLoader(URL url, URL origURL, MBeanServer server, ObjectName repositoryName)
UnifiedClassLoader constructor that can be used to register with a particular Loader Repository identified by ObjectName.

Method Summary

void	addURL(URL url) Append the given url to the URLs used for class and resource loading
void	clearBlacklists()
protected void	definePackage(String className) Define the package for the class if not already done
boolean	equals(Object other) This is here to document that this must delegate to the super implementation to perform identity based equality.
protected Class	findClass(String name) Called by loadClassLocally to find the requested class within this class loaders class path.
Enumeration	findResources(String name) Find all resource URLs for the given name.
Enumeration	findResourcesLocally(String name) Provides the same functionality as URLClassLoader.findResources(java.lang.String).
int	getAddedOrder()
URL[]	getAllURLs() Return all library URLs associated with this UnifiedClassLoader
URL[]	getClasspath() This method simply invokes the super.getURLs() method to access the list of URLs that make up the UnifiedClassLoader classpath.
LoaderRepository	getLoaderRepository()
ObjectName	getObjectName() Obtain the ObjectName under which the UCL can be registered with the JMX server.
URL	getOrigURL() Get the original URL associated with the UCL.
Package	getPackage(String name)
Package[]	getPackages()
protected PermissionCollection	getPermissions(CodeSource cs) Override the permissions accessor to use the CodeSource based on the original URL if one exists.
protected ProtectionDomain	getProtectionDomain() Determine the protection domain.
protected ProtectionDomain	getProtectionDomain(URL codesourceUrl) Determine the protection domain.
URL	getResource(String name) Attempts to load the resource from its URL and if not found forwards to the request to LoaderRepository.
URL	getResourceLocally(String name) Provides the same functionality as ClassLoader.getResource(java.lang.String).
URL	getURL() Get the URL associated with the UCL.
URL[]	getURLs() Return an empty URL array to force the RMI marshalling subsystem to use the java.server.codebase property as the annotated codebase.
int	hashCode() This is here to document that this must delegate to the super implementation to perform identity based hashing.
protected byte[]	loadByteCode(String classname) Obtain the bytecode for the indicated class from this class loaders classpath.
Class	loadClass(String name, boolean resolve) The only caller of this method should be the VM initiated loadClassInternal() method.
Class	loadClassLocally(String name, boolean resolve) Called to attempt to load a class from the set of URLs associated with the UCL.
void	setAddedOrder(int addedOrder)
void	setRepository(LoaderRepository repository)
String	toString() Retruns a string representaion of this UCL.
void	unregister()

Methods inherited from class java.net.URLClassLoader

definePackage, findResource, newInstance, newInstance

Methods inherited from class java.security.SecureClassLoader

defineClass

Methods inherited from class java.lang.ClassLoader

clearAssertionStatus, defineClass, defineClass, defineClass, definePackage, findLibrary, findLoadedClass, findSystemClass, getParent, getResourceAsStream, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, loadClass, resolveClass, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus, setSigners

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

repository

protected LoaderRepository repository

Reference to the unified repository.

unregisterTrace

protected Exception unregisterTrace

The location where unregister is called from

url

protected URL url

One URL per ClassLoader in our case

origURL

protected URL origURL

An optional URL from which url may have been copied. It is used to allow the security permissions to be based on a static url namespace.

Constructor Detail

UnifiedClassLoader

public UnifiedClassLoader(URL url)

Construct a UnifiedClassLoader without registering it to the classloader repository.

Parameters:

url - the single URL to load classes from.

UnifiedClassLoader

public UnifiedClassLoader(URL url,
                          URL origURL)

Construct a UnifiedClassLoader without registering it to the classloader repository.

Parameters:

url - the single URL to load classes from.

origURL - the possibly null original URL from which url may be a local copy or nested jar.

UnifiedClassLoader

public UnifiedClassLoader(URL url,
                          URL origURL,
                          ClassLoader parent)

Construct a UnifiedClassLoader without registering with the classloader repository.

Parameters:

url - the single URL to load classes from.

origURL - the possibly null original URL from which url may be a local copy or nested jar.

parent - the parent class loader to use

UnifiedClassLoader

public UnifiedClassLoader(URL url,
                          LoaderRepository repository)

Construct a UnifiedClassLoader and registers it to the given repository.

Parameters:

url - The single URL to load classes from.

repository - the repository this classloader delegates to

UnifiedClassLoader

public UnifiedClassLoader(URL url,
                          URL origURL,
                          LoaderRepository repository)

Construct a UnifiedClassLoader and registers it to the given repository.

Parameters:

url - The single URL to load classes from.

origURL - the possibly null original URL from which url may be a local copy or nested jar.

repository - the repository this classloader delegates to be a local copy or nested jar.

UnifiedClassLoader

public UnifiedClassLoader(URL url,
                          MBeanServer server,
                          ObjectName repositoryName)
                   throws Exception

UnifiedClassLoader constructor that can be used to register with a particular Loader Repository identified by ObjectName.

Parameters:

url - an URL value

server - a MBeanServer value

repositoryName - an ObjectName value

Throws:

Exception - if an error occurs

UnifiedClassLoader

public UnifiedClassLoader(URL url,
                          URL origURL,
                          MBeanServer server,
                          ObjectName repositoryName)
                   throws Exception

UnifiedClassLoader constructor that can be used to register with a particular Loader Repository identified by ObjectName.

Parameters:

url - an URL value

origURL - the possibly null original URL from which url may be a local copy or nested jar.

server - a MBeanServer value

repositoryName - an ObjectName value

Throws:

Exception - if an error occurs

Method Detail

getAddedOrder

public int getAddedOrder()

setAddedOrder

public void setAddedOrder(int addedOrder)

getObjectName

public ObjectName getObjectName()
                         throws MalformedObjectNameException

Obtain the ObjectName under which the UCL can be registered with the JMX server. This creates a name of the form "jmx.loading:UCL=hashCode" since we don't currently care that UCL be easily queriable.

Throws:

MalformedObjectNameException

unregister

public void unregister()

addURL

public void addURL(URL url)

Append the given url to the URLs used for class and resource loading

Parameters:

url - the URL to load from

clearBlacklists

public void clearBlacklists()

getLoaderRepository

public LoaderRepository getLoaderRepository()

setRepository

public void setRepository(LoaderRepository repository)

loadClassLocally

public Class loadClassLocally(String name,
                              boolean resolve)
                       throws ClassNotFoundException

Called to attempt to load a class from the set of URLs associated with the UCL.

Throws:

ClassNotFoundException

getResourceLocally

public URL getResourceLocally(String name)

Provides the same functionality as ClassLoader.getResource(java.lang.String).

Specified by:

getResourceLocally in interface org.jboss.util.loading.Translatable

getURL

public URL getURL()

Get the URL associated with the UCL.

getOrigURL

public URL getOrigURL()

Get the original URL associated with the UCL. This may be null.

getClasspath

public URL[] getClasspath()

This method simply invokes the super.getURLs() method to access the list of URLs that make up the UnifiedClassLoader classpath.

loadClass

public Class loadClass(String name,
                       boolean resolve)
                throws ClassNotFoundException

The only caller of this method should be the VM initiated loadClassInternal() method. This method attempts to acquire the UnifiedLoaderRepository2 lock and then asks the repository to load the class.

Forwards request to LoaderRepository.

Throws:

ClassNotFoundException

getResource

public URL getResource(String name)

Attempts to load the resource from its URL and if not found forwards to the request to LoaderRepository.

findResources

public Enumeration findResources(String name)
                          throws IOException

Find all resource URLs for the given name. This overrides the URLClassLoader version to look for resources in the repository.

Parameters:

name - the name of the resource

Returns:

Enumeration

Throws:

IOException

findResourcesLocally

public Enumeration findResourcesLocally(String name)
                                 throws IOException

Provides the same functionality as URLClassLoader.findResources(java.lang.String).

Throws:

IOException

hashCode

public final int hashCode()

This is here to document that this must delegate to the super implementation to perform identity based hashing. Using URL based hashing caused conflicts with the Class.forName(String, boolean, ClassLoader).

equals

public final boolean equals(Object other)

This is here to document that this must delegate to the super implementation to perform identity based equality. Using URL based equality caused conflicts with the Class.forName(String, boolean, ClassLoader).

getAllURLs

public URL[] getAllURLs()

Return all library URLs associated with this UnifiedClassLoader

Do not remove this method without running the WebIntegrationTestSuite

getURLs

public URL[] getURLs()

Return an empty URL array to force the RMI marshalling subsystem to use the java.server.codebase property as the annotated codebase.

Do not remove this method without discussing it on the dev list.

Returns:

Empty URL[]

getPackage

public Package getPackage(String name)

getPackages

public Package[] getPackages()

toString

public String toString()

Retruns a string representaion of this UCL.

findClass

protected Class findClass(String name)
                   throws ClassNotFoundException

Called by loadClassLocally to find the requested class within this class loaders class path.

Parameters:

name - the name of the class

Returns:

the resulting class

Throws:

ClassNotFoundException - if the class could not be found

definePackage

protected void definePackage(String className)

Define the package for the class if not already done

Parameters:

className - the class name

getPermissions

protected PermissionCollection getPermissions(CodeSource cs)

Override the permissions accessor to use the CodeSource based on the original URL if one exists. This allows the security policy to be defined in terms of the static URL namespace rather than the local copy or nested URL. This builds a PermissionCollection from: 1. The origURL CodeSource 2. The argument CodeSource 3. The Policy.getPermission(origURL CodeSource) This is necessary because we cannot define the CodeSource the SecureClassLoader uses to register the class under.

Parameters:

cs - the location and signatures of the codebase.

getProtectionDomain

protected ProtectionDomain getProtectionDomain()

Determine the protection domain. If we are a copy of the original deployment, use the original url as the codebase.

Returns:

the protection domain

getProtectionDomain

protected ProtectionDomain getProtectionDomain(URL codesourceUrl)

Determine the protection domain. If we are a copy of the original deployment, use the original url as the codebase.

Returns:

the protection domain

loadByteCode

protected byte[] loadByteCode(String classname)
                       throws ClassNotFoundException,
                              IOException

Obtain the bytecode for the indicated class from this class loaders classpath.

Parameters:

classname -

Returns:

the bytecode array if found

Throws:

ClassNotFoundException - - if the class resource could not be found

IOException