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 class loader implementation is loaded in a different class loader (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 TomcatInstrumentableClassLoader.

Since:

2.0

Author:

Costin Leau, Juergen Hoeller

See Also:

addTransformer(java.lang.instrument.ClassFileTransformer), getThrowawayClassLoader(), SimpleThrowawayClassLoader, TomcatInstrumentableClassLoader

Constructor Summary

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

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

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:

IllegalArgumentException - if the supplied ClassLoader is null

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 class file transformer to be applied by this load-time weaver.

Specified by:

addTransformer in interface LoadTimeWeaver

Parameters:

transformer - the class file transformer to add

getInstrumentableClassLoader

public ClassLoader getInstrumentableClassLoader()

Description copied from interface: LoadTimeWeaver

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

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

Specified by:

getInstrumentableClassLoader in interface LoadTimeWeaver

Returns:

a class loader that supports instrumentation through AspectJ-style load-time weaving based on user-defined ClassFileTransformers

getThrowawayClassLoader

public ClassLoader getThrowawayClassLoader()

Description copied from interface: LoadTimeWeaver

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

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 class loader; should return a new instance for each call, with no existing state