org.springframework.instrument.classloading

Class ReflectiveLoadTimeWeaver

java.lang.Object

org.springframework.instrument.classloading.ReflectiveLoadTimeWeaver

All Implemented Interfaces:

LoadTimeWeaver

public class ReflectiveLoadTimeWeaver
extends Object
implements LoadTimeWeaver

LoadTimeWeaver which uses reflection to delegate to an underlying ClassLoader with well-known transformation hooks. The underlying ClassLoader is expected to support the following weaving methods (as defined in the LoadTimeWeaver interface):

• public void addTransformer(java.lang.instrument.ClassFileTransformer): for registering the given ClassFileTransformer on this ClassLoader
• public ClassLoader getThrowawayClassLoader(): for obtaining a throwaway class loader for this ClassLoader (optional; ReflectiveLoadTimeWeaver will fall back to a SimpleThrowawayClassLoader if that method isn't available)

Please note that the above methods must reside in a class that is publicly accessible, although the class itself does not have to be visible to the application's class loader.

The reflective nature of this LoadTimeWeaver is particularly useful when the underlying ClassLoader implementation is loaded in a different class loader itself (such as the application server's class loader which is not visible to the web application). There is no direct API dependency between this LoadTimeWeaver adapter and the underlying ClassLoader, just a 'loose' method contract.

This is the LoadTimeWeaver to use in combination with Spring's org.springframework.instrument.classloading.tomcat.TomcatInstrumentableClassLoader for Tomcat 5.0+ as well as with the Resin application server version 3.1+.

Since:

2.0

Author:

Costin Leau, Juergen Hoeller

See Also:

addTransformer(java.lang.instrument.ClassFileTransformer), getThrowawayClassLoader(), SimpleThrowawayClassLoader, org.springframework.instrument.classloading.tomcat.TomcatInstrumentableClassLoader

Constructor Summary

Constructors

Constructor and Description
ReflectiveLoadTimeWeaver() Create a new ReflectiveLoadTimeWeaver for the current context class loader, which needs to support the required weaving methods.
ReflectiveLoadTimeWeaver(ClassLoader classLoader) Create a new SimpleLoadTimeWeaver for the given class loader.

Method Summary

Methods

Modifier and Type	Method and Description
void	addTransformer(ClassFileTransformer transformer) Add a ClassFileTransformer to be applied by this LoadTimeWeaver.
ClassLoader	getInstrumentableClassLoader() Return a ClassLoader that supports instrumentation through AspectJ-style load-time weaving based on user-defined ClassFileTransformers.
ClassLoader	getThrowawayClassLoader() Return a throwaway ClassLoader, enabling classes to be loaded and inspected without affecting the parent ClassLoader.

Methods inherited from class java.lang.Object

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

Constructor Detail

ReflectiveLoadTimeWeaver

public ReflectiveLoadTimeWeaver()

Create a new ReflectiveLoadTimeWeaver for the current context class loader, which needs to support the required weaving methods.

ReflectiveLoadTimeWeaver

public ReflectiveLoadTimeWeaver(ClassLoader classLoader)

Create a new SimpleLoadTimeWeaver for the given class loader.

Parameters:

classLoader - the ClassLoader to delegate to for weaving (must support the required weaving methods).

Throws:

IllegalStateException - if the supplied ClassLoader does not support the required weaving methods

Method Detail

addTransformer

public void addTransformer(ClassFileTransformer transformer)

Description copied from interface: LoadTimeWeaver

Add a ClassFileTransformer to be applied by this LoadTimeWeaver.

Specified by:

addTransformer in interface LoadTimeWeaver

Parameters:

transformer - the ClassFileTransformer to add

getInstrumentableClassLoader

public ClassLoader getInstrumentableClassLoader()

Description copied from interface: LoadTimeWeaver

Return a ClassLoader that supports instrumentation through AspectJ-style load-time weaving based on user-defined ClassFileTransformers.

May be the current ClassLoader, or a ClassLoader created by this LoadTimeWeaver instance.

Specified by:

getInstrumentableClassLoader in interface LoadTimeWeaver

Returns:

the ClassLoader which will expose instrumented classes according to the registered transformers

getThrowawayClassLoader

public ClassLoader getThrowawayClassLoader()

Description copied from interface: LoadTimeWeaver

Return a throwaway ClassLoader, enabling classes to be loaded and inspected without affecting the parent ClassLoader.

Should not return the same instance of the ClassLoader returned from an invocation of LoadTimeWeaver.getInstrumentableClassLoader().

Specified by:

getThrowawayClassLoader in interface LoadTimeWeaver

Returns:

a temporary throwaway ClassLoader; should return a new instance for each call, with no existing state