1 /* 2 * Copyright (c) 2013, 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 package com.oracle.java.testlibrary; 25 26 import java.security.SecureClassLoader; 27 28 /** 29 * {@code ByteCodeLoader} can be used for easy loading of byte code already 30 * present in memory. 31 * 32 * {@code InMemoryCompiler} can be used for compiling source code in a string 33 * into byte code, which then can be loaded with {@code ByteCodeLoader}. 34 * 35 * @see InMemoryCompiler 36 */ 37 public class ByteCodeLoader extends SecureClassLoader { 38 private final String className; 39 private final byte[] byteCode; 40 private volatile Class<?> holder; 41 42 /** 43 * Creates a new {@code ByteCodeLoader} ready to load a class with the 44 * given name and the given byte code. 45 * 46 * @param className The name of the class 47 * @param byteCode The byte code of the class 48 */ 49 public ByteCodeLoader(String className, byte[] byteCode) { 50 this.className = className; 51 this.byteCode = byteCode; 52 } 53 54 @Override 55 public Class<?> loadClass(String name) throws ClassNotFoundException { 56 if (!name.equals(className)) { 57 return super.loadClass(name); 58 } 59 if (holder == null) { 60 synchronized(this) { 61 if (holder == null) { 62 holder = findClass(name); 63 } 64 } 65 } 66 return holder; 67 } 68 69 @Override 70 protected Class<?> findClass(String name) throws ClassNotFoundException { 71 if (!name.equals(className)) { 72 throw new ClassNotFoundException(name); 73 } 74 75 return defineClass(name, byteCode, 0, byteCode.length); 76 } 77 78 /** 79 * Utility method for creating a new {@code ByteCodeLoader} and then 80 * directly load the given byte code. 81 * 82 * @param className The name of the class 83 * @param byteCode The byte code for the class 84 * @throws ClassNotFoundException if the class can't be loaded 85 * @return A {@see Class} object representing the class 86 */ 87 public static Class<?> load(String className, byte[] byteCode) throws ClassNotFoundException { 88 return new ByteCodeLoader(className, byteCode).loadClass(className); 89 } 90 }