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225 lines
8.4 KiB
225 lines
8.4 KiB
/*
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* Copyright (c) 2007, 2018, Oracle and/or its affiliates. All rights reserved.
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*/
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package com.sun.org.apache.bcel.internal.util;
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/* ====================================================================
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* The Apache Software License, Version 1.1
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*
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* Copyright (c) 2001 The Apache Software Foundation. All rights
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* reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. The end-user documentation included with the redistribution,
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* if any, must include the following acknowledgment:
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* "This product includes software developed by the
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* Apache Software Foundation (http://www.apache.org/)."
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* Alternately, this acknowledgment may appear in the software itself,
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* if and wherever such third-party acknowledgments normally appear.
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*
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* 4. The names "Apache" and "Apache Software Foundation" and
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* "Apache BCEL" must not be used to endorse or promote products
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* derived from this software without prior written permission. For
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* written permission, please contact apache@apache.org.
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*
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* 5. Products derived from this software may not be called "Apache",
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* "Apache BCEL", nor may "Apache" appear in their name, without
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* prior written permission of the Apache Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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* ====================================================================
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*
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* This software consists of voluntary contributions made by many
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* individuals on behalf of the Apache Software Foundation. For more
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* information on the Apache Software Foundation, please see
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* <http://www.apache.org/>.
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*/
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import java.util.Hashtable;
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import java.io.*;
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import com.sun.org.apache.bcel.internal.*;
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import com.sun.org.apache.bcel.internal.classfile.*;
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/**
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* <p>Drop in replacement for the standard class loader of the JVM. You can use it
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* in conjunction with the JavaWrapper to dynamically modify/create classes
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* as they're requested.</p>
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*
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* <p>This class loader recognizes special requests in a distinct
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* format, i.e., when the name of the requested class contains with
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* "$$BCEL$$" it calls the createClass() method with that name
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* (everything bevor the $$BCEL$$ is considered to be the package
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* name. You can subclass the class loader and override that
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* method. "Normal" classes class can be modified by overriding the
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* modifyClass() method which is called just before defineClass().</p>
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*
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* <p>There may be a number of packages where you have to use the default
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* class loader (which may also be faster). You can define the set of packages
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* where to use the system class loader in the constructor. The default value contains
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* "java.", "sun.", "javax."</p>
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*
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* @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
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* @see JavaWrapper
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* @see ClassPath
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*/
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public class ClassLoader extends java.lang.ClassLoader {
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private Hashtable classes = new Hashtable(); // Hashtable is synchronized thus thread-safe
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private String[] ignored_packages = {
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"java.", "javax.", "sun."
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};
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private Repository repository = SyntheticRepository.getInstance();
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private java.lang.ClassLoader deferTo = ClassLoader.getSystemClassLoader();
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public ClassLoader() {
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}
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public ClassLoader(java.lang.ClassLoader deferTo) {
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this.deferTo = deferTo;
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this.repository = new ClassLoaderRepository(deferTo);
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}
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/** @param ignored_packages classes contained in these packages will be loaded
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* with the system class loader
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*/
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public ClassLoader(String[] ignored_packages) {
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addIgnoredPkgs(ignored_packages);
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}
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public ClassLoader(java.lang.ClassLoader deferTo, String [] ignored_packages) {
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this.deferTo = deferTo;
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this.repository = new ClassLoaderRepository(deferTo);
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addIgnoredPkgs(ignored_packages);
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}
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private void addIgnoredPkgs(String[] ignored_packages) {
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String[] new_p = new String[ignored_packages.length + this.ignored_packages.length];
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System.arraycopy(this.ignored_packages, 0, new_p, 0, this.ignored_packages.length);
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System.arraycopy(ignored_packages, 0, new_p, this.ignored_packages.length,
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ignored_packages.length);
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this.ignored_packages = new_p;
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}
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protected Class loadClass(String class_name, boolean resolve)
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throws ClassNotFoundException
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{
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Class cl = null;
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/* First try: lookup hash table.
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*/
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if((cl=(Class)classes.get(class_name)) == null) {
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/* Second try: Load system class using system class loader. You better
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* don't mess around with them.
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*/
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for(int i=0; i < ignored_packages.length; i++) {
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if(class_name.startsWith(ignored_packages[i])) {
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cl = deferTo.loadClass(class_name);
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break;
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}
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}
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if(cl == null) {
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JavaClass clazz = null;
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/* Third try: Special request?
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*/
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if(class_name.indexOf("$$BCEL$$") >= 0)
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clazz = createClass(class_name);
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else { // Fourth try: Load classes via repository
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if ((clazz = repository.loadClass(class_name)) != null) {
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clazz = modifyClass(clazz);
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}
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else
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throw new ClassNotFoundException(class_name);
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}
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if(clazz != null) {
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byte[] bytes = clazz.getBytes();
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cl = defineClass(class_name, bytes, 0, bytes.length);
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} else // Fourth try: Use default class loader
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cl = Class.forName(class_name);
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}
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if(resolve)
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resolveClass(cl);
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}
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classes.put(class_name, cl);
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return cl;
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}
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/** Override this method if you want to alter a class before it gets actually
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* loaded. Does nothing by default.
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*/
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protected JavaClass modifyClass(JavaClass clazz) {
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return clazz;
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}
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/**
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* Override this method to create you own classes on the fly. The
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* name contains the special token $$BCEL$$. Everything before that
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* token is consddered to be a package name. You can encode you own
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* arguments into the subsequent string. You must regard however not
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* to use any "illegal" characters, i.e., characters that may not
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* appear in a Java class name too<br>
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*
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* The default implementation interprets the string as a encoded compressed
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* Java class, unpacks and decodes it with the Utility.decode() method, and
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* parses the resulting byte array and returns the resulting JavaClass object.
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*
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* @param class_name compressed byte code with "$$BCEL$$" in it
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*/
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protected JavaClass createClass(String class_name) {
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int index = class_name.indexOf("$$BCEL$$");
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String real_name = class_name.substring(index + 8);
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JavaClass clazz = null;
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try {
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byte[] bytes = Utility.decode(real_name, true);
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ClassParser parser = new ClassParser(new ByteArrayInputStream(bytes), "foo");
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clazz = parser.parse();
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} catch(Throwable e) {
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e.printStackTrace();
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return null;
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}
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// Adapt the class name to the passed value
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ConstantPool cp = clazz.getConstantPool();
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ConstantClass cl = (ConstantClass)cp.getConstant(clazz.getClassNameIndex(),
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Constants.CONSTANT_Class);
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ConstantUtf8 name = (ConstantUtf8)cp.getConstant(cl.getNameIndex(),
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Constants.CONSTANT_Utf8);
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name.setBytes(class_name.replace('.', '/'));
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return clazz;
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}
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}
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