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, Child, and Grand. 31 public class ClassLoaderForChildGrandFoo extends ClassLoader { 32 33 ClassLoader l2 = null; 34 35 private final Set<String> names = new HashSet<>(); 36 37 public ClassLoaderForChildGrandFoo(String... names) { 38 for (String n : names) this.names.add(n); 39 } 40 41 protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException { 42 // Create class loader l2 to load Parent and Foo. And, pass this class 43 // loader to l2 so l2 can use it to load Grand. 44 if (name.contains("Parent") && l2 == null) { 45 l2 = new ClassLoaderForParentFoo(this, "pkg.Foo", "pkg.Grand", "pkg.Parent"); 46 Class<?> b = l2.loadClass("pkg.Parent"); 47 return b; 48 } 49 if (!names.contains(name)) return super.loadClass(name, resolve); 50 Class<?> result = findLoadedClass(name); 51 52 if (result == null) { 53 String filename = name.replace('.', '/') + ".class"; 54 try (InputStream data = getResourceAsStream(filename)) { 55 if (data == null) throw new ClassNotFoundException(); 56 try (ByteArrayOutputStream buffer = new ByteArrayOutputStream()) { 57 int b; 58 do { 59 b = data.read(); 60 if (b >= 0) buffer.write(b); 61 } while (b >= 0); 62 byte[] bytes = buffer.toByteArray(); 63 result = defineClass(name, bytes, 0, bytes.length); 64 } 65 } catch (IOException e) { 66 throw new ClassNotFoundException("Error reading class file", e); 67 } 68 } 69 if (resolve) resolveClass(result); 70 return result; 71 } 72 73 }