net.sf.farrago.plugin
Class FarragoPluginClassLoader

java.lang.Object
  java.lang.ClassLoader
      java.security.SecureClassLoader
          java.net.URLClassLoader
              net.sf.farrago.plugin.FarragoPluginClassLoader

public class FarragoPluginClassLoader
extends URLClassLoader

FarragoPluginClassLoader allows plugin jars to be added to the ClassLoader dynamically.

Version:

$Id: //open/dev/farrago/src/net/sf/farrago/plugin/FarragoPluginClassLoader.java#16 $

Author:

John V. Sichi

Field Summary

static String	LIBRARY_CLASS_PREFIX1 Prefix used to indicate that a wrapper library is loaded directly from a class rather than a jar.
static String	LIBRARY_CLASS_PREFIX2 New alternative to LIBRARY_CLASS_PREFIX1.
static String	PLUGIN_FACTORY_CLASS_ATTRIBUTE Attribute name used in jar manifest for identifying the class to be used as a plugin factory.
static String	PLUGIN_MODEL_ATTRIBUTE Attribute name used in jar manifest for identifying the XMI file to be used as a model extension.
private static Logger	tracer
private Set	urlSet

Constructor Summary

FarragoPluginClassLoader()

FarragoPluginClassLoader(ClassLoader parentClassLoader)

Method Summary

void	addPluginUrl(URL url) Adds a URL from which plugins can be loaded.
protected Class<?>	findClass(String name)
static String	getLibraryClassReference(String libraryName) From a library name which references a Java class directly, obtains the class reference (possibly with trailing context such as a method name).
static boolean	isLibraryClass(String libraryName) Tests whether a library name references a Java class directly rather than a jar.
Class	loadClassFromJarUrl(String jarUrl, String className) Loads a Java class from a jar URL.
Class	loadClassFromJarUrlManifest(String jarUrl, String jarAttributeName) Loads a Java class from a jar URL, using the manifest to determine the classname.
Class	loadClassFromLibraryManifest(String libraryName, String jarAttributeName) Loads a Java class from a library (either a jarfile using a manifest to get the classname, or else a named class from the classpath).
Object	newPluginInstance(Class pluginClass) Constructs a new object instance of a plugin class, making sure the thread's context ClassLoader is set to this for the duration of the construction.

Methods inherited from class java.net.URLClassLoader

addURL, definePackage, findResource, findResources, getPermissions, 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, findLibrary, findLoadedClass, findSystemClass, getPackage, getPackages, getParent, getResource, getResourceAsStream, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, loadClass, loadClass, resolveClass, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus, setSigners

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

tracer

private static final Logger tracer

LIBRARY_CLASS_PREFIX1

public static final String LIBRARY_CLASS_PREFIX1

Prefix used to indicate that a wrapper library is loaded directly from a class rather than a jar. TODO: get rid of this and use only LIBRARY_CLASS_PREFIX2.

See Also:

Constant Field Values

LIBRARY_CLASS_PREFIX2

public static final String LIBRARY_CLASS_PREFIX2

New alternative to LIBRARY_CLASS_PREFIX1.

See Also:

Constant Field Values

PLUGIN_FACTORY_CLASS_ATTRIBUTE

public static final String PLUGIN_FACTORY_CLASS_ATTRIBUTE

Attribute name used in jar manifest for identifying the class to be used as a plugin factory.

See Also:

Constant Field Values

PLUGIN_MODEL_ATTRIBUTE

public static final String PLUGIN_MODEL_ATTRIBUTE

Attribute name used in jar manifest for identifying the XMI file to be used as a model extension.

See Also:

Constant Field Values

urlSet

private final Set urlSet

Constructor Detail

FarragoPluginClassLoader

public FarragoPluginClassLoader()

FarragoPluginClassLoader

public FarragoPluginClassLoader(ClassLoader parentClassLoader)

Method Detail

addPluginUrl

public void addPluginUrl(URL url)

Adds a URL from which plugins can be loaded.

Parameters:

url - URL to add

loadClassFromLibraryManifest

public Class loadClassFromLibraryManifest(String libraryName,
                                          String jarAttributeName)

Loads a Java class from a library (either a jarfile using a manifest to get the classname, or else a named class from the classpath).

Parameters:

libraryName - filename of jar containing plugin implementation

jarAttributeName - name of jar attribute to use to determine class name

Returns:

loaded class

findClass

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

Overrides:

findClass in class URLClassLoader

Throws:

ClassNotFoundException

loadClassFromJarUrlManifest

public Class loadClassFromJarUrlManifest(String jarUrl,
                                         String jarAttributeName)

Loads a Java class from a jar URL, using the manifest to determine the classname.

Parameters:

jarUrl - URL of jar containing plugin implementation

jarAttributeName - name of jar attribute to use to determine class name

Returns:

loaded class

loadClassFromJarUrl

public Class loadClassFromJarUrl(String jarUrl,
                                 String className)

Loads a Java class from a jar URL.

Parameters:

jarUrl - URL for jar containing class implementation

className - name of class to load

Returns:

loaded class

newPluginInstance

public Object newPluginInstance(Class pluginClass)
                         throws InstantiationException,
                                IllegalAccessException

Constructs a new object instance of a plugin class, making sure the thread's context ClassLoader is set to this for the duration of the construction.

Parameters:

pluginClass - class to instantiate

Returns:

new object

Throws:

InstantiationException

IllegalAccessException

isLibraryClass

public static boolean isLibraryClass(String libraryName)

Tests whether a library name references a Java class directly rather than a jar.

Parameters:

libraryName - library name to be tested

Returns:

true iff libraryName references a Java class

getLibraryClassReference

public static String getLibraryClassReference(String libraryName)

From a library name which references a Java class directly, obtains the class reference (possibly with trailing context such as a method name).

Parameters:

libraryName - library name to be parsed

Returns:

class name