| /* |
| * reserved comment block |
| * DO NOT REMOVE OR ALTER! |
| */ |
| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.sun.org.apache.bcel.internal.util; |
| |
| |
| import java.util.Hashtable; |
| import java.io.*; |
| import com.sun.org.apache.bcel.internal.*; |
| import com.sun.org.apache.bcel.internal.classfile.*; |
| |
| /** |
| * <p>Drop in replacement for the standard class loader of the JVM. You can use it |
| * in conjunction with the JavaWrapper to dynamically modify/create classes |
| * as they're requested.</p> |
| * |
| * <p>This class loader recognizes special requests in a distinct |
| * format, i.e., when the name of the requested class contains with |
| * "$$BCEL$$" it calls the createClass() method with that name |
| * (everything bevor the $$BCEL$$ is considered to be the package |
| * name. You can subclass the class loader and override that |
| * method. "Normal" classes class can be modified by overriding the |
| * modifyClass() method which is called just before defineClass().</p> |
| * |
| * <p>There may be a number of packages where you have to use the default |
| * class loader (which may also be faster). You can define the set of packages |
| * where to use the system class loader in the constructor. The default value contains |
| * "java.", "sun.", "javax."</p> |
| * |
| * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A> |
| * @see JavaWrapper |
| * @see ClassPath |
| */ |
| public class ClassLoader extends java.lang.ClassLoader { |
| private Hashtable classes = new Hashtable(); // Hashtable is synchronized thus thread-safe |
| private String[] ignored_packages = { |
| "java.", "javax.", "sun." |
| }; |
| private Repository repository = SyntheticRepository.getInstance(); |
| private java.lang.ClassLoader deferTo = ClassLoader.getSystemClassLoader(); |
| |
| public ClassLoader() { |
| } |
| |
| public ClassLoader(java.lang.ClassLoader deferTo) { |
| this.deferTo = deferTo; |
| this.repository = new ClassLoaderRepository(deferTo); |
| } |
| |
| /** @param ignored_packages classes contained in these packages will be loaded |
| * with the system class loader |
| */ |
| public ClassLoader(String[] ignored_packages) { |
| addIgnoredPkgs(ignored_packages); |
| } |
| |
| public ClassLoader(java.lang.ClassLoader deferTo, String [] ignored_packages) { |
| this.deferTo = deferTo; |
| this.repository = new ClassLoaderRepository(deferTo); |
| |
| addIgnoredPkgs(ignored_packages); |
| } |
| |
| private void addIgnoredPkgs(String[] ignored_packages) { |
| String[] new_p = new String[ignored_packages.length + this.ignored_packages.length]; |
| |
| System.arraycopy(this.ignored_packages, 0, new_p, 0, this.ignored_packages.length); |
| System.arraycopy(ignored_packages, 0, new_p, this.ignored_packages.length, |
| ignored_packages.length); |
| |
| this.ignored_packages = new_p; |
| } |
| |
| protected Class loadClass(String class_name, boolean resolve) |
| throws ClassNotFoundException |
| { |
| Class cl = null; |
| |
| /* First try: lookup hash table. |
| */ |
| if((cl=(Class)classes.get(class_name)) == null) { |
| /* Second try: Load system class using system class loader. You better |
| * don't mess around with them. |
| */ |
| for(int i=0; i < ignored_packages.length; i++) { |
| if(class_name.startsWith(ignored_packages[i])) { |
| cl = deferTo.loadClass(class_name); |
| break; |
| } |
| } |
| |
| if(cl == null) { |
| JavaClass clazz = null; |
| |
| /* Third try: Special request? |
| */ |
| if(class_name.indexOf("$$BCEL$$") >= 0) |
| clazz = createClass(class_name); |
| else { // Fourth try: Load classes via repository |
| if ((clazz = repository.loadClass(class_name)) != null) { |
| clazz = modifyClass(clazz); |
| } |
| else |
| throw new ClassNotFoundException(class_name); |
| } |
| |
| if(clazz != null) { |
| byte[] bytes = clazz.getBytes(); |
| cl = defineClass(class_name, bytes, 0, bytes.length); |
| } else // Fourth try: Use default class loader |
| cl = Class.forName(class_name); |
| } |
| |
| if(resolve) |
| resolveClass(cl); |
| } |
| |
| classes.put(class_name, cl); |
| |
| return cl; |
| } |
| |
| /** Override this method if you want to alter a class before it gets actually |
| * loaded. Does nothing by default. |
| */ |
| protected JavaClass modifyClass(JavaClass clazz) { |
| return clazz; |
| } |
| |
| /** |
| * Override this method to create you own classes on the fly. The |
| * name contains the special token $$BCEL$$. Everything before that |
| * token is consddered to be a package name. You can encode you own |
| * arguments into the subsequent string. You must regard however not |
| * to use any "illegal" characters, i.e., characters that may not |
| * appear in a Java class name too<br> |
| * |
| * The default implementation interprets the string as a encoded compressed |
| * Java class, unpacks and decodes it with the Utility.decode() method, and |
| * parses the resulting byte array and returns the resulting JavaClass object. |
| * |
| * @param class_name compressed byte code with "$$BCEL$$" in it |
| */ |
| protected JavaClass createClass(String class_name) { |
| int index = class_name.indexOf("$$BCEL$$"); |
| String real_name = class_name.substring(index + 8); |
| |
| JavaClass clazz = null; |
| try { |
| byte[] bytes = Utility.decode(real_name, true); |
| ClassParser parser = new ClassParser(new ByteArrayInputStream(bytes), "foo"); |
| |
| clazz = parser.parse(); |
| } catch(Throwable e) { |
| e.printStackTrace(); |
| return null; |
| } |
| |
| // Adapt the class name to the passed value |
| ConstantPool cp = clazz.getConstantPool(); |
| |
| ConstantClass cl = (ConstantClass)cp.getConstant(clazz.getClassNameIndex(), |
| Constants.CONSTANT_Class); |
| ConstantUtf8 name = (ConstantUtf8)cp.getConstant(cl.getNameIndex(), |
| Constants.CONSTANT_Utf8); |
| name.setBytes(class_name.replace('.', '/')); |
| |
| return clazz; |
| } |
| } |