org.glassfish.internal.api

Interface ClassLoaderHierarchy

All Known Implementing Classes:

ClassLoaderHierarchyImpl

@Contract
public interface ClassLoaderHierarchy

This class is responsible foe creation of class loader hierarchy of an application.

Author:

[email protected]

Method Summary

Modifier and Type	Method and Description
ClassLoader	createApplicationParentCL(ClassLoader parent, DeploymentContext context) Sets up the parent class loader for the application class loader.
ClassLoader	getAPIClassLoader() Returns a ClassLoader that can load classes exported by any OSGi bundle in the system for public use.
DelegatingClassLoader.ClassFinder	getAppLibClassFinder(List<URI> libURIs) Returns ApplibClassFinder.
ClassLoader	getAppLibClassLoader(String application, List<URI> libURIs) Returns AppLibClassLoader.
ClassLoader	getCommonClassLoader() Returns a class loader that is common to all deployed applications.
String	getCommonClassPath() Returns the classpath equiavalent to what is used by classloader returned by getCommonClassLoader().
DelegatingClassLoader	getConnectorClassLoader(String application) Returns the class loader which has visibility to appropriate list of standalone RARs deployed in the server.

Method Detail

getAPIClassLoader

ClassLoader getAPIClassLoader()

Returns a ClassLoader that can load classes exported by any OSGi bundle in the system for public use. Such classes include Java EE API, AMX API, appserv-ext API, etc. CommonClassLoader delegates to this class loader.

Returns:

a ClassLoader that can load classes exported by any bundles

getCommonClassLoader

ClassLoader getCommonClassLoader()

Returns a class loader that is common to all deployed applications. Common Class Loader is responsible for loading classes from following URLs (the order is strictly maintained): lib/*.jar:domain_dir/lib/classes:domain_dir/lib/*.jar. Please note that domain_dir/lib/classes comes before domain_dir/lib/*.jar, just like WEB-INF/classes is searched first before WEB-INF/lib/*.jar. It delegates to APIClassLoader.

Returns:

ClassLoader common to all deployed applications.

See Also:

getAPIClassLoader()

getCommonClassPath

String getCommonClassPath()

Returns the classpath equiavalent to what is used by classloader returned by getCommonClassLoader(). Classpath entries are separated by File.separatorChar, but don't assume there will be any leading or trailing separator char. It returns an empty string if there are no libraries installed.

Returns:

ClassPath separated by File.pathSeparatorChar

getConnectorClassLoader

DelegatingClassLoader getConnectorClassLoader(String application)

Returns the class loader which has visibility to appropriate list of standalone RARs deployed in the server. Depending on a policy, this can either return a singleton classloader for all applications or a class loader specific to an application. When a singleton class loader is returned, such a class loader will have visibility to all the standalone RARs deployed in the system. When a class loader specific to an application is returned, such a class loader will have visibility to only standalone RARs that the application depends on.

Parameters:

application - Application whose class loader hierarchy is being set

Returns:

class loader which has visibility to appropriate list of standalone RARs.

getAppLibClassLoader

ClassLoader getAppLibClassLoader(String application,
                                 List<URI> libURIs)
                          throws MalformedURLException

Returns AppLibClassLoader. As the name suggests, this class loader has visibility to deploy time libraries (--libraries and EXTENSION_LIST of MANIFEST.MF, provided the library is available in 'applibs' directory) for an application. It is different from CommonClassLoader in a sense that the libraries that are part of common class loader are shared by all applications, where as this class loader adds a scope to a library.

Parameters:

application - Application for which this class loader is created

libURIs - list of URIs, where each URI represent a library

Returns:

class loader that has visibility to appropriate application specific libraries.

Throws:

MalformedURLException

See Also:

#getAppLibClassFinder(List)

getAppLibClassFinder

DelegatingClassLoader.ClassFinder getAppLibClassFinder(List<URI> libURIs)
                                                throws MalformedURLException

Returns ApplibClassFinder. As the name suggests, this class finder has visibility to deploy time libraries (--libraries and EXTENSION_LIST of MANIFEST.MF, provided the library is available in 'applibs' directory) for an application. It is different from CommonClassLoader in a sense that the libraries that are part of common class loader are shared by all applications, where as this class loader adds a scope to a library.
NOTE : Difference between this API and getAppLibClassLoader(String, List<URI>) is the latter will be used by all applications (for its parent classloader) whereas this API will be used only by connector classloader. All other application classloaders will have AppLibClassLoader as parent where as connector classloader will be above AppLibClassLoader and hence simple delegation is not feasible.

Parameters:

libURIs - list of URIs, where each URI represent a library

Returns:

class loader that has visibility to appropriate application specific libraries.

Throws:

MalformedURLException

See Also:

#getAppLibClassLoader(String, List)

createApplicationParentCL

ClassLoader createApplicationParentCL(ClassLoader parent,
                                      DeploymentContext context)
                               throws com.sun.enterprise.module.ResolveError

Sets up the parent class loader for the application class loader. Application class loader are under the control of the ArchiveHandler since a special archive file format will require a specific class loader. However GlassFish needs to be able to add capabilities to the application like adding APIs accessibility, this is done through its parent class loader which we create and maintain.

Parameters:

parent - the parent class loader

context - deployment context

Returns:

class loader capable of loading public APIs identified by the deployers

Throws:

com.sun.enterprise.module.ResolveError - if one of the deployer's public API module is not found.