| /* |
| * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code 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 |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| import java.io.*; |
| import java.lang.reflect.*; |
| import java.util.jar.*; |
| |
| public class Util { |
| /** |
| * Invoke the loader.defineClass() class method to define the class stored in clsFile, |
| * with the following modification: |
| * <ul> |
| * <li> All ASCII strings in the class file bytes that matches fromString will be replaced with toString. |
| * NOTE: the two strings must be the exact same length. |
| * </ul> |
| */ |
| public static Class defineModifiedClass(ClassLoader loader, File clsFile, String fromString, String toString) |
| throws FileNotFoundException, IOException, NoSuchMethodException, IllegalAccessException, |
| InvocationTargetException |
| { |
| try (DataInputStream dis = new DataInputStream(new FileInputStream(clsFile))) { |
| byte[] buff = new byte[(int)clsFile.length()]; |
| dis.readFully(buff); |
| replace(buff, fromString, toString); |
| |
| System.out.println("Loading from: " + clsFile + " (" + buff.length + " bytes)"); |
| |
| Method defineClass = ClassLoader.class.getDeclaredMethod("defineClass", |
| buff.getClass(), int.class, int.class); |
| defineClass.setAccessible(true); |
| |
| // We directly call into ClassLoader.defineClass() to define the "Super" class. Also, |
| // rewrite its classfile so that it returns ___yyy___ instead of ___xxx___. Changing the |
| // classfile will guarantee that this class will NOT be loaded from the CDS archive. |
| Class cls = (Class)defineClass.invoke(loader, buff, new Integer(0), new Integer(buff.length)); |
| System.out.println("Loaded : " + cls); |
| |
| return cls; |
| } |
| } |
| |
| /** |
| * @return the number of occurrences of the <code>from</code> string that |
| * have been replaced. |
| */ |
| public static int replace(byte buff[], String from, String to) { |
| if (to.length() != from.length()) { |
| throw new RuntimeException("bad strings"); |
| } |
| byte f[] = asciibytes(from); |
| byte t[] = asciibytes(to); |
| byte f0 = f[0]; |
| |
| int numReplaced = 0; |
| int max = buff.length - f.length; |
| for (int i=0; i<max; ) { |
| if (buff[i] == f0 && replace(buff, f, t, i)) { |
| i += f.length; |
| numReplaced ++; |
| } else { |
| i++; |
| } |
| } |
| return numReplaced; |
| } |
| |
| public static boolean replace(byte buff[], byte f[], byte t[], int i) { |
| for (int x=0; x<f.length; x++) { |
| if (buff[x+i] != f[x]) { |
| return false; |
| } |
| } |
| for (int x=0; x<f.length; x++) { |
| buff[x+i] = t[x]; |
| } |
| return true; |
| } |
| |
| static byte[] asciibytes(String s) { |
| byte b[] = new byte[s.length()]; |
| for (int i=0; i<b.length; i++) { |
| b[i] = (byte)s.charAt(i); |
| } |
| return b; |
| } |
| |
| public static Class defineClassFromJAR(ClassLoader loader, File jarFile, String className) |
| throws FileNotFoundException, IOException, NoSuchMethodException, IllegalAccessException, |
| InvocationTargetException { |
| return defineClassFromJAR(loader, jarFile, className, null, null); |
| } |
| |
| /** |
| * Invoke the loader.defineClass() class method to define the named class stored in a JAR file. |
| * |
| * If a class exists both in the classpath, as well as in the list of URLs of a URLClassLoader, |
| * by default, the URLClassLoader will not define the class, and instead will delegate to the |
| * app loader. This method is an easy way to force the class to be defined by the URLClassLoader. |
| * |
| * Optionally, you can modify the contents of the classfile buffer. See comments in |
| * defineModifiedClass. |
| */ |
| public static Class defineClassFromJAR(ClassLoader loader, File jarFile, String className, |
| String fromString, String toString) |
| throws FileNotFoundException, IOException, NoSuchMethodException, IllegalAccessException, |
| InvocationTargetException |
| { |
| byte[] buff = getClassFileFromJar(jarFile, className); |
| |
| if (fromString != null) { |
| replace(buff, fromString, toString); |
| } |
| |
| //System.out.println("Loading from: " + ent + " (" + buff.length + " bytes)"); |
| |
| Method defineClass = ClassLoader.class.getDeclaredMethod("defineClass", |
| buff.getClass(), int.class, int.class); |
| defineClass.setAccessible(true); |
| Class cls = (Class)defineClass.invoke(loader, buff, new Integer(0), new Integer(buff.length)); |
| |
| //System.out.println("Loaded : " + cls); |
| return cls; |
| } |
| |
| public static byte[] getClassFileFromJar(File jarFile, String className) throws FileNotFoundException, IOException { |
| JarFile jf = new JarFile(jarFile); |
| JarEntry ent = jf.getJarEntry(className.replace('.', '/') + ".class"); |
| |
| try (DataInputStream dis = new DataInputStream(jf.getInputStream(ent))) { |
| byte[] buff = new byte[(int)ent.getSize()]; |
| dis.readFully(buff); |
| return buff; |
| } |
| } |
| } |