org.openmrs.module

Class ModuleClassLoader

java.lang.Object

java.lang.ClassLoader

java.security.SecureClassLoader

java.net.URLClassLoader

org.openmrs.module.ModuleClassLoader

All Implemented Interfaces:

Closeable, AutoCloseable

public class ModuleClassLoader
extends URLClassLoader

Standard implementation of module class loader.
Code adapted from the Java Plug-in Framework (JPF) - LGPL - Copyright (C)
2004-2006 Dmitry Olshansky

Constructor Summary

Constructors

Modifier	Constructor and Description
	ModuleClassLoader(Module module, ClassLoader parent) Creates class instance configured to load classes and resources for given module.
protected	ModuleClassLoader(Module module, List<URL> urls)
protected	ModuleClassLoader(Module module, List<URL> urls, ClassLoader parent)
protected	ModuleClassLoader(Module module, List<URL> urls, ClassLoader parent, URLStreamHandlerFactory factory)

Method Summary

Modifier and Type	Method and Description
protected File	cacheLibrary(URL libUrl, String libname) Saves the given library in the openmrs cache.
protected void	checkClassVisibility(Class<?> cls, ModuleClassLoader requestor) Checking the given class's visibility in this module
protected static Module[]	collectAwareOfModuleImports(Module module) Get and cache the imports for this module.
protected static Module[]	collectRequiredModuleImports(Module module) Get and cache the imports for this module.
void	dispose()
protected String	findLibrary(String name)
URL	findResource(String name) If a resource is found within a jar, that jar URL is converted to a temporary file and a URL to that is returned
protected URL	findResource(String name, ModuleClassLoader requestor, Set<String> seenModules) Find a resource (image, file, etc) in the module structure
protected void	findResources(List<URL> result, String name, ModuleClassLoader requestor, Set<String> seenModules) Find all occurrences of a resource (image, file, etc) in the module structure
Enumeration<URL>	findResources(String name)
static File	getLibCacheFolderForModule(Module module) Get the library cache folder for the given module.
Module	getModule()
Set<String>	getProvidedPackages() Contains all class packages provided by the module, including those contained in jars.
boolean	isDisposed()
protected boolean	isResourceVisible(String name, URL url, ModuleClassLoader requestor) Check if the given resource (image, file, etc) is visible by this classloader
protected Class<?>	loadClass(String name, boolean resolve)
protected Class<?>	loadClass(String name, boolean resolve, ModuleClassLoader requestor, Set<String> seenModules) Custom loadClass implementation to allow for loading from a given ModuleClassLoader and skip the modules that have been tried already
protected void	modulesSetChanged()
void	setProbeParentLoaderLast(boolean value) Allow the probe parent loader last variable to be set.
String	toString()

Methods inherited from class java.net.URLClassLoader

addURL, close, definePackage, findClass, getPermissions, getResourceAsStream, getURLs, newInstance, newInstance

Methods inherited from class java.security.SecureClassLoader

defineClass, defineClass

Methods inherited from class java.lang.ClassLoader

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

Constructor Detail

ModuleClassLoader

protected ModuleClassLoader(Module module,
                            List<URL> urls,
                            ClassLoader parent,
                            URLStreamHandlerFactory factory)

Parameters:

module - Module

urls - resources "managed" by this class loader

parent - parent class loader

factory - URL stream handler factory

See Also:

URLClassLoader(java.net.URL[], java.lang.ClassLoader, java.net.URLStreamHandlerFactory)

ModuleClassLoader

protected ModuleClassLoader(Module module,
                            List<URL> urls,
                            ClassLoader parent)

Parameters:

module - the Module to load

urls - List<URL> of the resources "managed" by this class loader

parent - parent ClassLoader

See Also:

URLClassLoader(java.net.URL[], java.lang.ClassLoader)

ModuleClassLoader

protected ModuleClassLoader(Module module,
                            List<URL> urls)

Parameters:

module - the Module to load

urls - List<URL> of thee resources "managed" by this class loader

See Also:

URLClassLoader(java.net.URL[])

ModuleClassLoader

public ModuleClassLoader(Module module,
                         ClassLoader parent)

Creates class instance configured to load classes and resources for given module.

Parameters:

module - the Module to load

parent - parent ClassLoader

Method Detail

getModule

public Module getModule()

Returns:

returns this classloader's module

isDisposed

public boolean isDisposed()

getLibCacheFolderForModule

public static File getLibCacheFolderForModule(Module module)

Get the library cache folder for the given module. Each module has a different cache folder to ease cleanup when unloading a module while openmrs is running

Parameters:

module - Module which the cache will be used for

Returns:

File directory where the files will be placed

collectRequiredModuleImports

protected static Module[] collectRequiredModuleImports(Module module)

Get and cache the imports for this module. The imports should just be the modules that set as "required" by this module

collectAwareOfModuleImports

protected static Module[] collectAwareOfModuleImports(Module module)

Get and cache the imports for this module. The imports should just be the modules that set as "aware of" by this module

modulesSetChanged

protected void modulesSetChanged()

See Also:

modulesSetChanged()

dispose

public void dispose()

See Also:

ModuleFactory.stopModule(Module, boolean)

setProbeParentLoaderLast

public void setProbeParentLoaderLast(boolean value)

Allow the probe parent loader last variable to be set. Usually this is set to true to allow modules to override and create their own classes

Parameters:

value - boolean true/false whether or not to look at the parent classloader last

loadClass

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

Overrides:

loadClass in class ClassLoader

Throws:

ClassNotFoundException

See Also:

ClassLoader.loadClass(java.lang.String, boolean)

loadClass

protected Class<?> loadClass(String name,
                             boolean resolve,
                             ModuleClassLoader requestor,
                             Set<String> seenModules)
                      throws ClassNotFoundException

Custom loadClass implementation to allow for loading from a given ModuleClassLoader and skip the modules that have been tried already

Parameters:

name - String path and name of the class to load

resolve - boolean whether or not to resolve this class before returning

requestor - ModuleClassLoader with which to try loading

seenModules - Set<String> moduleIds that have been tried already

Returns:

Class that has been loaded

Throws:

ClassNotFoundException - if no class found

checkClassVisibility

protected void checkClassVisibility(Class<?> cls,
                                    ModuleClassLoader requestor)
                             throws ClassNotFoundException

Checking the given class's visibility in this module

Parameters:

cls - Class to check

requestor - ModuleClassLoader to check against

Throws:

ClassNotFoundException

findLibrary

protected String findLibrary(String name)

Overrides:

findLibrary in class ClassLoader

See Also:

ClassLoader.findLibrary(java.lang.String)

cacheLibrary

protected File cacheLibrary(URL libUrl,
                            String libname)

Saves the given library in the openmrs cache. This prevents locking of jars/files by servlet container

Parameters:

libUrl - URL to the library/jar file

libname - name of the jar that will be the name of the cached file

Returns:

file that is now copied and cached

findResource

public URL findResource(String name)

If a resource is found within a jar, that jar URL is converted to a temporary file and a URL to that is returned

Overrides:

findResource in class URLClassLoader

See Also:

ClassLoader.findResource(java.lang.String)

findResources

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

Overrides:

findResources in class URLClassLoader

Throws:

IOException

See Also:

ClassLoader.findResources(java.lang.String)

findResource

protected URL findResource(String name,
                           ModuleClassLoader requestor,
                           Set<String> seenModules)

Find a resource (image, file, etc) in the module structure

Parameters:

name - String path and name of the file

requestor - ModuleClassLoader in which to look

seenModules - Set<String> modules that have been checked already

Returns:

URL to resource

See Also:

findResource(String)

findResources

protected void findResources(List<URL> result,
                             String name,
                             ModuleClassLoader requestor,
                             Set<String> seenModules)
                      throws IOException

Find all occurrences of a resource (image, file, etc) in the module structure

Parameters:

result - URL of the file found

name - String path and name of the file to find

requestor - ModuleClassLoader in which to start

seenModules - Set<String> moduleIds that have been checked already

Throws:

IOException

See Also:

findResources(String), findResource(String, ModuleClassLoader, Set)

isResourceVisible

protected boolean isResourceVisible(String name,
                                    URL url,
                                    ModuleClassLoader requestor)

Check if the given resource (image, file, etc) is visible by this classloader

Parameters:

name - String path and name to check

url - URL of the library file

requestor - ModuleClassLoader in which to look

Returns:

true/false whether this resource is visibile by this classloader

getProvidedPackages

public Set<String> getProvidedPackages()

Contains all class packages provided by the module, including those contained in jars.

It is used by OpenmrsClassLoader.loadClass(String, boolean) and in particular ModuleFactory.getModuleClassLoadersForPackage(String) to quickly find possible loaders for the given class. Although it takes some time to extract all provided packages from a module, it pays off when loading classes. It is much faster to query a map of packages than iterating over all class loaders to find which one to use.

Returns:

the provided packages

toString

public String toString()

Overrides:

toString in class Object

See Also:

Object.toString()