libjava/classpath/java/lang/instrument/Instrumentation.java

   1 /* Instrumentation.java -- Implementation of this interface is used to
   2    instrument Java bytecode.
   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 /**
  43  * An Instrumentation object has transformers that will
  44  * be called each time a class is defined or redefined.
  45  * The object is given to a <code>premain</code> function
  46  * that is called before the <code>main</code> function.
  47  *
  48  * @author Nicolas Geoffray (nicolas.geoffray@menlina.com)
  49  * @since 1.5
  50  */
  51 public interface Instrumentation
  52 {
  53
  54   /**
  55    * Adds a <code>ClassFileTransformer</class> object
  56    * to the instrumentation. Each time a class is defined
  57    * or redefined, the <code>transform</code> method of the
  58    * <code>transformer</code> object is called.
  59    *
  60    * @param transformer the transformer to add
  61    * @throws NullPointerException if transformer is null
  62    */
  63   void addTransformer(ClassFileTransformer transformer);
  64
  65   /**
  66    * Removes the given transformer from the set of transformers
  67    * this Instrumentation object has.
  68    *
  69    * @param transformer the transformer to remove
  70    * @return true if the transformer was found and removed, false if
  71    * the transformer was not found
  72    * @throws NullPointerException if transformer is null
  73    */
  74   boolean removeTransformer(ClassFileTransformer transformer);
  75
  76   /**
  77    * Returns if the current JVM supports class redefinition
  78    *
  79    * @return true if the current JVM supports class redefinition
  80    */
  81   boolean isRedefineClassesSupported();
  82
  83   /**
  84    * Redefine classes present in the definitions array, with
  85    * the corresponding class files.
  86    *
  87    * @param definitions an array of classes to redefine
  88    *
  89    * @throws ClassNotFoundException if a class cannot be found
  90    * @throws UnmodifiableClassException if a class cannot be modified
  91    * @throws UnsupportedOperationException if the JVM does not support
  92    * redefinition or the redefinition made unsupported changes
  93    * @throws ClassFormatError if a class file is not valid
  94    * @throws NoClassDefFoundError if a class name is not equal to the name
  95    * in the class file specified
  96    * @throws UnsupportedClassVersionError if the class file version numbers
  97    * are unsupported
  98    * @throws ClassCircularityError if circularity occured with the new
  99    * classes
 100    * @throws LinkageError if a linkage error occurs
 101    * @throws NullPointerException if the definitions array is null, or any
 102    * of its element
 103    *
 104    * @see #isRedefineClassesSupported()
 105    * @see #addTransformer(java.lang.instrument.ClassFileTransformer)
 106    * @see ClassFileTransformer
 107    */
 108   void redefineClasses(ClassDefinition[] definitions)
 109                      throws ClassNotFoundException,
 110                             UnmodifiableClassException;
 111
 112
 113   /**
 114    * Get all the classes loaded by the JVM.
 115    *
 116    * @return an array containing all the classes loaded by the JVM. The array
 117    * is empty if no class is loaded.
 118    */
 119   Class[] getAllLoadedClasses();
 120
 121   /**
 122    * Get all the classes loaded by a given class loader
 123    *
 124    * @param loader the loader
 125    *
 126    * @return an array containing all the classes loaded by the given loader.
 127    * The array is empty if no class was loaded by the loader.
 128    */
 129   Class[] getInitiatedClasses(ClassLoader loader);
 130
 131   /**
 132    * Get the size of an object. It contains the size of all fields.
 133    *
 134    * @param objectToSize the object
 135    * @return the size of the object
 136    * @throws NullPointerException if objectToSize is null.
 137    */
 138   long getObjectSize(Object objectToSize);
 139 }