Source for java.lang.instrument.ClassFileTransformer

   1: /* ClassFileTransformer.java -- Implementation of this interface is used by an agent to
   2:    transform class files.
   3:    Copyright (C) 2005  Free Software Foundation, Inc.
   4: 
   5: This file is part of GNU Classpath.
   6: 
   7: GNU Classpath is free software; you can redistribute it and/or modify
   8: it under the terms of the GNU General Public License as published by
   9: the Free Software Foundation; either version 2, or (at your option)
  10: any later version.
  11: 
  12: GNU Classpath is distributed in the hope that it will be useful, but
  13: WITHOUT ANY WARRANTY; without even the implied warranty of
  14: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15: General Public License for more details.
  16: 
  17: You should have received a copy of the GNU General Public License
  18: along with GNU Classpath; see the file COPYING.  If not, write to the
  19: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  20: 02110-1301 USA.
  21: 
  22: Linking this library statically or dynamically with other modules is
  23: making a combined work based on this library.  Thus, the terms and
  24: conditions of the GNU General Public License cover the whole
  25: combination.
  26: 
  27: As a special exception, the copyright holders of this library give you
  28: permission to link this library with independent modules to produce an
  29: executable, regardless of the license terms of these independent
  30: modules, and to copy and distribute the resulting executable under
  31: terms of your choice, provided that you also meet, for each linked
  32: independent module, the terms and conditions of the license of that
  33: module.  An independent module is a module which is not derived from
  34: or based on this library.  If you modify this library, you may extend
  35: this exception to your version of the library, but you are not
  36: obligated to do so.  If you do not wish to do so, delete this
  37: exception statement from your version. */
  38: 
  39: 
  40: package java.lang.instrument;
  41: 
  42: import java.security.ProtectionDomain;
  43: 
  44: /**
  45:  * This interface should be implemented by classes wishing to transform
  46:  * classes bytecode when defining or redefining classes.
  47:  *
  48:  * @author Nicolas Geoffray (nicolas.geoffray@menlina.com)
  49:  * @see Instrumentation
  50:  * @see Instrumentation#addTransformer(java.lang.instrument.ClassFileTransformer)
  51:  * @see Instrumentation#removeTransformer(java.lang.instrument.ClassFileTransformer)
  52:  * @since 1.5
  53:  */
  54: public interface ClassFileTransformer
  55: {
  56: 
  57:   /**
  58:    * Implementation of this method transforms a class by redefining its
  59:    * bytecodes. Once a ClassFileTransformer object registers itself to the
  60:    * Instrumentation object, this method will be called each time a class is
  61:    * defined (<code>ClassLoader.defineClass</code>) or redefined
  62:    * (<code>Instrumentation.redefineClasses</code>)
  63:    * @param loader the loader of the class
  64:    * @param className the name of the class with packages separated with "/"
  65:    * @param classBeingRedefined the class being redefined if it's the case,
  66:    * null otherwise
  67:    * @param protectionDomain the protection domain of the class being defined or
  68:    * redefined
  69:    * @param classfileBuffer the input byte buffer in class file format
  70:    * 
  71:    * @return a class file buffer or null when no transformation has been performed
  72:    * 
  73:    * @throws IllegalClassFormatException if the byte buffer does not represent
  74:    * a well-formed class file
  75:    * @see Instrumentation#redefineClasses(java.lang.instrument.ClassDefinition[])
  76:    *
  77:    */
  78:   byte[] transform(ClassLoader loader,
  79:                  String className,
  80:                  Class<?> classBeingRedefined,
  81:                  ProtectionDomain protectionDomain,
  82:                  byte[] classfileBuffer)
  83:                  throws IllegalClassFormatException;
  84: }