org.springframework.instrument.classloading

Class InstrumentationLoadTimeWeaver

java.lang.Object

org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver

All Implemented Interfaces:

LoadTimeWeaver

public class InstrumentationLoadTimeWeaver
extends java.lang.Object
implements LoadTimeWeaver

LoadTimeWeaver relying on VM Instrumentation.

Start the JVM specifying the Java agent to be used, like as follows:

-javaagent:path/to/org.springframework.instrument.jar

where org.springframework.instrument.jar is a JAR file containing the InstrumentationSavingAgent class, as shipped with Spring.

In Eclipse, for example, set the "Run configuration"'s JVM args to be of the form:

-javaagent:${project_loc}/lib/org.springframework.instrument.jar

Since:

2.0

Author:

Rod Johnson, Juergen Hoeller

See Also:

InstrumentationSavingAgent

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	InstrumentationLoadTimeWeaver.FilteringClassFileTransformer Decorator that only applies the given target transformer to a specific ClassLoader.
private static class	InstrumentationLoadTimeWeaver.InstrumentationAccessor Inner class to avoid InstrumentationSavingAgent dependency.

Field Summary

Fields

Modifier and Type	Field and Description
private static boolean	AGENT_CLASS_PRESENT
private java.lang.ClassLoader	classLoader
private java.lang.instrument.Instrumentation	instrumentation
private java.util.List<java.lang.instrument.ClassFileTransformer>	transformers

Constructor Summary

Constructors

Constructor and Description
InstrumentationLoadTimeWeaver() Create a new InstrumentationLoadTimeWeaver for the default ClassLoader.
InstrumentationLoadTimeWeaver(java.lang.ClassLoader classLoader) Create a new InstrumentationLoadTimeWeaver for the given ClassLoader.

Method Summary

Modifier and Type	Method and Description
void	addTransformer(java.lang.instrument.ClassFileTransformer transformer) Add a ClassFileTransformer to be applied by this LoadTimeWeaver.
java.lang.ClassLoader	getInstrumentableClassLoader() We have the ability to weave the current class loader when starting the JVM in this way, so the instrumentable class loader will always be the current loader.
private static java.lang.instrument.Instrumentation	getInstrumentation() Obtain the Instrumentation instance for the current VM, if available.
java.lang.ClassLoader	getThrowawayClassLoader() This implementation always returns a SimpleThrowawayClassLoader.
static boolean	isInstrumentationAvailable() Check whether an Instrumentation instance is available for the current VM.
void	removeTransformers() Remove all registered transformers, in inverse order of registration.

Methods inherited from class java.lang.Object

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

Field Detail

AGENT_CLASS_PRESENT

private static final boolean AGENT_CLASS_PRESENT

classLoader

private final java.lang.ClassLoader classLoader

instrumentation

private final java.lang.instrument.Instrumentation instrumentation

transformers

private final java.util.List<java.lang.instrument.ClassFileTransformer> transformers

Constructor Detail

InstrumentationLoadTimeWeaver

public InstrumentationLoadTimeWeaver()

Create a new InstrumentationLoadTimeWeaver for the default ClassLoader.

InstrumentationLoadTimeWeaver

public InstrumentationLoadTimeWeaver(java.lang.ClassLoader classLoader)

Create a new InstrumentationLoadTimeWeaver for the given ClassLoader.

Parameters:

classLoader - the ClassLoader that registered transformers are supposed to apply to

Method Detail

addTransformer

public void addTransformer(java.lang.instrument.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 java.lang.ClassLoader getInstrumentableClassLoader()

We have the ability to weave the current class loader when starting the JVM in this way, so the instrumentable class loader will always be the current loader.

Specified by:

getInstrumentableClassLoader in interface LoadTimeWeaver

Returns:

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

getThrowawayClassLoader

public java.lang.ClassLoader getThrowawayClassLoader()

This implementation always returns a SimpleThrowawayClassLoader.

Specified by:

getThrowawayClassLoader in interface LoadTimeWeaver

Returns:

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

removeTransformers

public void removeTransformers()

Remove all registered transformers, in inverse order of registration.

isInstrumentationAvailable

public static boolean isInstrumentationAvailable()

Check whether an Instrumentation instance is available for the current VM.

See Also:

getInstrumentation()

getInstrumentation

private static java.lang.instrument.Instrumentation getInstrumentation()

Obtain the Instrumentation instance for the current VM, if available.

Returns:

the Instrumentation instance, or null if none found

See Also:

isInstrumentationAvailable()