1 /* 2 * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 package pkg; 26 27 import java.util.*; 28 import java.io.*; 29 30 // This class loader loads Foo and Parent and calls back to l1 to load Grand. 31 public class ClassLoaderForParentFoo extends ClassLoader { 32 33 private final Set<String> names = new HashSet<>(); 34 35 ClassLoader l1; 36 37 public ClassLoaderForParentFoo(ClassLoader l, String... names) { 38 l1 = l; 39 for (String n : names) this.names.add(n); 40 } 41 42 protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException { 43 if (name.contains("Grand")) return l1.loadClass("pkg.Grand"); 44 if (!names.contains(name)) return super.loadClass(name, resolve); 45 Class<?> result = findLoadedClass(name); 46 if (result == null) { 47 // Load our own version of Foo that will be referenced by Parent. 48 if (name.contains("Parent")) loadClass("pkg.Foo", resolve); 49 String filename = name.replace('.', '/') + ".class"; 50 try (InputStream data = getResourceAsStream(filename)) { 51 if (data == null) throw new ClassNotFoundException(); 52 try (ByteArrayOutputStream buffer = new ByteArrayOutputStream()) { 53 int b; 54 do { 55 b = data.read(); 56 if (b >= 0) buffer.write(b); 57 } while (b >= 0); 58 byte[] bytes = buffer.toByteArray(); 59 result = defineClass(name, bytes, 0, bytes.length); 60 } 61 } catch (IOException e) { 62 throw new ClassNotFoundException("Error reading class file", e); 63 } 64 } 65 if (resolve) resolveClass(result); 66 return result; 67 } 68 69 }