org.ops4j.pax.web.service.spi.servlet

Class OsgiServletContextClassLoader

java.lang.Object

java.lang.ClassLoader

org.ops4j.pax.web.service.spi.servlet.OsgiServletContextClassLoader

All Implemented Interfaces:

org.osgi.framework.BundleReference

public class OsgiServletContextClassLoader
extends ClassLoader
implements org.osgi.framework.BundleReference

A ClassLoader added in Pax Web to replace all pax-swissbox/xbean bundle classloaders and to be used as the ClassLoader for OsgiServletContext.

In Whiteboard scenario, an OsgiServletContext should get a ClassLoader from a bundle that was used to register ServletContextHelper OSGi service and in case of servlets (and filters), the ServletContext obtained from ServletConfig should return (in ServletContext.getClassLoader()) the ClassLoader of a bundle associated with the Bundle that registered this Servlet or Filter OSGi service.

In practice (and in WAB scenario), the actual ClassLoader returned from OsgiServletContext should also be able to reach to resources/classes for given server runtime (Jetty, Tomcat, Undertow) and engines like JSP.

To this end, When an instance of OsgiServletContext is created by server-specific ServerController, an instance of OsgiServletContextClassLoader will be created and set as the ClassLoader of the runtime-specific ServletContext.

This ClassLoader doesn't follow the delegation model - it has no parent and simply collects the resources and attempts classloading from all the bundles. It never calls ClassLoader.defineClass(byte[], int, int) on its own.

To get the picture, here are three methods for all three supported runtimes:

• org.eclipse.jetty.server.handler.ContextHandler#setClassLoader(java.lang.ClassLoader)
• org.apache.catalina.core.ContainerBase#setParentClassLoader(java.lang.ClassLoader)
• io.undertow.servlet.api.DeploymentInfo#setClassLoader(java.lang.ClassLoader)

By default (outside of OSGi), here are the actual classloader classes used:

• org.eclipse.jetty.webapp.WebAppClassLoader
• org.apache.catalina.loader.ParallelWebappClassLoader and org.apache.catalina.loader.WebappLoader
• Nothing particular in plain Undertow, but it's set to org.jboss.as.web.host.WebDeploymentBuilder#getClassLoader() in Wildfly/EAP.

This ClassLoader implements BundleReference

Constructor Summary

Constructors

Constructor and Description
OsgiServletContextClassLoader()

Method Summary

Modifier and Type	Method and Description
void	addBundle(org.osgi.framework.Bundle bundle) Adds a Bundle to be reachable from this ClassLoader
void	addBundles(org.osgi.framework.Bundle... bundle) Adds bundles to be reachable from this ClassLoader
protected Class<?>	findClass(String name)
protected URL	findResource(String name)
protected Enumeration<URL>	findResources(String name)
org.osgi.framework.Bundle	getBundle()
List<org.osgi.framework.Bundle>	getBundles()
Class<?>	loadClass(String name)
void	makeImmutable() After adding all bundles that back up this ClassLoader, this method prevents adding more bundles.

Methods inherited from class java.lang.ClassLoader

clearAssertionStatus, defineClass, defineClass, defineClass, defineClass, definePackage, findLibrary, findLoadedClass, findSystemClass, getClassLoadingLock, getPackage, getPackages, getParent, getResource, 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

Constructor Detail

OsgiServletContextClassLoader

public OsgiServletContextClassLoader()

Method Detail

getBundle

public org.osgi.framework.Bundle getBundle()

Specified by:

getBundle in interface org.osgi.framework.BundleReference

addBundle

public void addBundle(org.osgi.framework.Bundle bundle)

Adds a Bundle to be reachable from this ClassLoader

Parameters:

bundle -

addBundles

public void addBundles(org.osgi.framework.Bundle... bundle)

Adds bundles to be reachable from this ClassLoader

Parameters:

bundle -

getBundles

public List<org.osgi.framework.Bundle> getBundles()

makeImmutable

public void makeImmutable()

After adding all bundles that back up this ClassLoader, this method prevents adding more bundles.

loadClass

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

Overrides:

loadClass 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

findClass

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

Overrides:

findClass in class ClassLoader

Throws:

ClassNotFoundException