org.netbeans
Class ProxyClassLoader

java.lang.Object
  java.lang.ClassLoader
      org.netbeans.ProxyClassLoader

Direct Known Subclasses:

JarClassLoader

public class ProxyClassLoader
extends ClassLoader

A class loader that has multiple parents and uses them for loading classes and resources. It is optimized for working in the enviroment of a deeply nested classloader hierarchy. It uses shared knowledge about package population to route the loading request directly to the correct classloader. It doesn't load classes or resources itself, but allows subclasses to add such functionality.

Constructor Summary

ProxyClassLoader(ClassLoader[] parents, boolean transitive)
Create a multi-parented classloader.

Method Summary

protected void	addCoveredPackages(Iterable<String> coveredPackages)
void	append(ClassLoader[] nueparents) Add new parents dynamically.
protected Package	definePackage(String name, String specTitle, String specVersion, String specVendor, String implTitle, String implVersion, String implVendor, URL sealBase) This is here just for locking serialization purposes.
void	destroy() Called before releasing the classloader so it can itself unregister from the global ClassLoader pool
protected Class	doLoadClass(String pkg, String name) This ClassLoader can't load anything itself.
URL	findResource(String name) This ClassLoader can't load anything itself.
Enumeration<URL>	findResources(String name)
protected Package	getPackage(String name) Returns a Package that has been defined by this class loader or any of its parents.
protected Package	getPackageFast(String name, boolean recurse) Faster way to find a package.
protected Package[]	getPackages() Returns all of the Packages defined by this class loader and its parents.
URL	getResource(String name) Finds the resource with the given name.
Enumeration<URL>	getResources(String name)
protected Class	loadClass(String name, boolean resolve) Loads the class with the specified name.
protected void	setSystemClassLoader(ClassLoader s)
protected boolean	shouldDelegateResource(String pkg, ClassLoader parent)

Methods inherited from class java.lang.ClassLoader

clearAssertionStatus, defineClass, defineClass, defineClass, defineClass, findClass, findLibrary, findLoadedClass, findSystemClass, getParent, getResourceAsStream, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, loadClass, 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

ProxyClassLoader

public ProxyClassLoader(ClassLoader[] parents,
                        boolean transitive)

Create a multi-parented classloader.

Parameters:

parents - all direct parents of this classloader, except system one.

transitive - whether other PCLs depending on this one will automatically search through its parent list

Method Detail

addCoveredPackages

protected final void addCoveredPackages(Iterable<String> coveredPackages)

append

public void append(ClassLoader[] nueparents)
            throws IllegalArgumentException

Add new parents dynamically.

Parameters:

nueparents - the new parents to add (append to list)

Throws:

IllegalArgumentException - in case of a null or cyclic parent (duplicate OK)

loadClass

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

Loads the class with the specified name. The implementation of this method searches for classes in the following order:

1. Looks for a known package and pass the loading to the ClassLoader for that package.
2. For unknown packages passes the call directly already been loaded.

Overrides:

loadClass in class ClassLoader

Parameters:

name - the name of the class

resolve - if true then resolve the class

Returns:

the resulting Class object

Throws:

ClassNotFoundException - if the class could not be found

doLoadClass

protected Class doLoadClass(String pkg,
                            String name)

This ClassLoader can't load anything itself. Subclasses may override this method to do some class loading themselves. The implementation should not throw any exception, just return null if it can't load required class.

Parameters:

name - the name of the class

Returns:

the resulting Class object or null

getResource

public final URL getResource(String name)

Finds the resource with the given name.

Overrides:

getResource in class ClassLoader

Parameters:

name - a "/"-separated path name that identifies the resource.

Returns:

a URL for reading the resource, or null if the resource could not be found.

See Also:

findResource(String)

findResource

public URL findResource(String name)

This ClassLoader can't load anything itself. Subclasses may override this method to do some resource loading themselves.

Overrides:

findResource in class ClassLoader

Parameters:

name - the resource name

Returns:

a URL for reading the resource, or null if the resource could not be found.

getResources

public final Enumeration<URL> getResources(String name)
                                    throws IOException

Overrides:

getResources in class ClassLoader

Throws:

IOException

findResources

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

Overrides:

findResources in class ClassLoader

Throws:

IOException

getPackage

protected Package getPackage(String name)

Returns a Package that has been defined by this class loader or any of its parents.

Overrides:

getPackage in class ClassLoader

Parameters:

name - the package name

Returns:

the Package corresponding to the given name, or null if not found

getPackageFast

protected Package getPackageFast(String name,
                                 boolean recurse)

Faster way to find a package.

Parameters:

name - package name in org.netbeans.modules.foo format

sname - package name in org/netbeans/modules/foo/ format

recurse - whether to also ask parents

Returns:

located package, or null

definePackage

protected Package definePackage(String name,
                                String specTitle,
                                String specVersion,
                                String specVendor,
                                String implTitle,
                                String implVersion,
                                String implVendor,
                                URL sealBase)
                         throws IllegalArgumentException

This is here just for locking serialization purposes. Delegates to super.definePackage with proper locking. Also tracks the package in our private cache, since getPackageFast(...,...,false) will not call super.getPackage.

Overrides:

definePackage in class ClassLoader

Throws:

IllegalArgumentException

getPackages

protected Package[] getPackages()

Returns all of the Packages defined by this class loader and its parents.

Overrides:

getPackages in class ClassLoader

Returns:

the array of Package objects defined by this ClassLoader

setSystemClassLoader

protected final void setSystemClassLoader(ClassLoader s)

shouldDelegateResource

protected boolean shouldDelegateResource(String pkg,
                                         ClassLoader parent)

destroy

public void destroy()

Called before releasing the classloader so it can itself unregister from the global ClassLoader pool