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gnu.java.lang

Class InstrumentationImpl

Implemented Interfaces:
Instrumentation
public final class InstrumentationImpl
extends Object
implements Instrumentation
An Instrumentation object has transformers that will be called each time a class is defined or redefined. The object is given to a premain function that is called before the main function.
Since:
1.5

Method Summary

void
addTransformer(ClassFileTransformer transformer)
Adds a ClassFileTransformer object to the instrumentation.
byte[]
callTransformers(ClassLoader loader, String className, Class classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer)
Called by the VM or redefineClasses to call each transformer
Class<T>[]
getAllLoadedClasses()
Get all the classes loaded by the JVM.
Class<T>[]
getInitiatedClasses(ClassLoader loader)
Get all the classes loaded by a given class loader
long
getObjectSize(Object objectToSize)
Get the size of an object.
boolean
isRedefineClassesSupported()
Returns if the current JVM supports class redefinition
void
redefineClasses(ClassDefinition[] definitions)
Redefine classes present in the definitions array, with the corresponding class files.
boolean
removeTransformer(ClassFileTransformer transformer)
Removes the given transformer from the set of transformers this Instrumentation object has.

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

addTransformer

public void addTransformer(ClassFileTransformer transformer)
Adds a ClassFileTransformer object to the instrumentation. Each time a class is defined or redefined, the transform method of the transformer object is called.
Specified by:
addTransformer in interface Instrumentation
Parameters:
transformer - the transformer to add
Throws:
NullPointerException - if transformer is null

callTransformers

public byte[] callTransformers(ClassLoader loader,
                               String className,
                               Class classBeingRedefined,
                               ProtectionDomain protectionDomain,
                               byte[] classfileBuffer)
Called by the VM or redefineClasses to call each transformer
Parameters:
loader - the loader of the class
className - the name of the class with packages separated with "/"
classBeingRedefined - the class being redefined if it's the case, null otherwise
protectionDomain - the protection domain of the class being defined or redefined
classfileBuffer - the input byte buffer in class file format
Returns:
the new class file

getAllLoadedClasses

public Class<T>[] getAllLoadedClasses()
Get all the classes loaded by the JVM.
Specified by:
getAllLoadedClasses in interface Instrumentation
Returns:
an array containing all the classes loaded by the JVM. The array is empty if no class is loaded.

getInitiatedClasses

public Class<T>[] getInitiatedClasses(ClassLoader loader)
Get all the classes loaded by a given class loader
Specified by:
getInitiatedClasses in interface Instrumentation
Parameters:
loader - the loader
Returns:
an array containing all the classes loaded by the given loader. The array is empty if no class was loaded by the loader.

getObjectSize

public long getObjectSize(Object objectToSize)
Get the size of an object.
Specified by:
getObjectSize in interface Instrumentation
Parameters:
objectToSize - the object
Returns:
the size of the object
Throws:
NullPointerException - if objectToSize is null.

isRedefineClassesSupported

public boolean isRedefineClassesSupported()
Returns if the current JVM supports class redefinition
Specified by:
isRedefineClassesSupported in interface Instrumentation
Returns:
true if the current JVM supports class redefinition

redefineClasses

public void redefineClasses(ClassDefinition[] definitions)
            throws ClassNotFoundException,
                   UnmodifiableClassException
Redefine classes present in the definitions array, with the corresponding class files.
Specified by:
redefineClasses in interface Instrumentation
Parameters:
definitions - an array of classes to redefine
Throws:
ClassNotFoundException - if a class cannot be found
UnmodifiableClassException - if a class cannot be modified
UnsupportedOperationException - if the JVM does not support redefinition or the redefinition made unsupported changes
NullPointerException - if the definitions array is null, or any of its element
See Also:
isRedefineClassesSupported(), addTransformer(java.lang.instrument.ClassFileTransformer), ClassFileTransformer

removeTransformer

public boolean removeTransformer(ClassFileTransformer transformer)
Removes the given transformer from the set of transformers this Instrumentation object has.
Specified by:
removeTransformer in interface Instrumentation
Parameters:
transformer - the transformer to remove
Returns:
true if the transformer was found and removed, false if the transformer was not found
Throws:
NullPointerException - if transformer is null
InstrumentationImpl.java -- GNU implementation of java.lang.instrument.Instrumentation Copyright (C) 2005, 2006 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.

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