Package io.github.classgraph

Interface ClassLoaderHandler

All Known Implementing Classes:

AntClassLoaderHandler, EquinoxClassLoaderHandler, EquinoxContextFinderClassLoaderHandler, FallbackClassLoaderHandler, FelixClassLoaderHandler, JBossClassLoaderHandler, JPMSClassLoaderHandler, OSGiDefaultClassLoaderHandler, URLClassLoaderHandler, WeblogicClassLoaderHandler, WebsphereLibertyClassLoaderHandler, WebsphereTraditionalClassLoaderHandler

public interface ClassLoaderHandler

A ClassLoader handler.

Custom ClassLoaderHandlers can be registered by listing their fully-qualified class name in the file: META-INF/services/io.github.classgraph.scanner.classloaderhandler.ClassLoaderHandler

However, if you do create a custom ClassLoaderHandler, please consider submitting a patch upstream for incorporation into ClassGraph.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static class	ClassLoaderHandler.DelegationOrder	The delegation order configuration for a given ClassLoader instance (this is usually PARENT_FIRST for most ClassLoaders, but this can be overridden by some ClassLoaders, e.g.

Method Summary

Modifier and Type	Method	Description
ClassLoaderHandler.DelegationOrder	getDelegationOrder(ClassLoader classLoaderInstance)	The delegation order configuration for a given ClassLoader instance (this is usually PARENT_FIRST for most ClassLoaders, since you don't generally want to be able to override system classes with user classes, but this can be overridden by some ClassLoaders, e.g.
ClassLoader	getEmbeddedClassLoader(ClassLoader outerClassLoaderInstance)	If this ClassLoader delegates directly to an embedded classloader instance, return it here, otherwise return null.
void	handle(ScanSpec scanSpec, ClassLoader classLoader, ClasspathOrder classpathOrderOut, LogNode log)	Determine if a given ClassLoader can be handled (meaning that its classpath elements can be extracted from it), and if it can, extract the classpath elements from the ClassLoader and register them with the ClasspathFinder using classpathFinder.addClasspathElement(pathElement) or classpathFinder.addClasspathElements(path).
String[]	handledClassLoaders()	The fully-qualified names of handled classloader classes.

Method Detail

handledClassLoaders

String[] handledClassLoaders()

The fully-qualified names of handled classloader classes.

Returns:

The names of ClassLoaders that this ClassLoaderHandler can handle.

getEmbeddedClassLoader

ClassLoader getEmbeddedClassLoader(ClassLoader outerClassLoaderInstance)

If this ClassLoader delegates directly to an embedded classloader instance, return it here, otherwise return null.

Parameters:

outerClassLoaderInstance - The outer ClassLoader instance to check for an embedded ClassLoader.

Returns:

The embedded ClassLoader to use instead of the outer ClassLoader, or null to use the outer ClassLoader.

getDelegationOrder

ClassLoaderHandler.DelegationOrder getDelegationOrder(ClassLoader classLoaderInstance)

The delegation order configuration for a given ClassLoader instance (this is usually PARENT_FIRST for most ClassLoaders, since you don't generally want to be able to override system classes with user classes, but this can be overridden by some ClassLoaders, e.g. WebSphere).

Parameters:

classLoaderInstance - The ClassLoader to get the delegation order for.

Returns:

The delegation order for the given ClassLoader.

handle

void handle(ScanSpec scanSpec,
            ClassLoader classLoader,
            ClasspathOrder classpathOrderOut,
            LogNode log)
     throws Exception

Determine if a given ClassLoader can be handled (meaning that its classpath elements can be extracted from it), and if it can, extract the classpath elements from the ClassLoader and register them with the ClasspathFinder using classpathFinder.addClasspathElement(pathElement) or classpathFinder.addClasspathElements(path).

Parameters:

scanSpec - the scanning specification, in case it is needed, e.g. this could be used to reduce the number of classpath elements returned in cases where it is very costly for a given classloader to return the entire classpath. (The ScanSpec can be safely ignored, however, and the returned paths will be filtered by ClassGraph.)

classLoader - The ClassLoader class to attempt to handle. If you can't directly use instanceof (because you are using introspection so that your ClassLoaderHandler implementation can be added to the upstream ClassGraph project), you should iterate through the ClassLoader's superclass lineage to ensure subclasses of the target ClassLoader are correctly detected.

classpathOrderOut - The ClasspathOrder to register any discovered classpath elements with.

log - A logger instance -- if this is non-null, write debug information using log.log("message").

Throws:

Exception - If anything goes wrong while fetching classpath elements.