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 import java.lang.instrument.ClassFileTransformer; 26 import java.lang.instrument.Instrumentation; 27 import java.lang.instrument.IllegalClassFormatException; 28 import java.security.ProtectionDomain; 29 30 public class AnonVmClassesDuringDumpTransformer implements ClassFileTransformer { 31 public byte[] transform(ClassLoader loader, String name, Class<?> classBeingRedefined, 32 ProtectionDomain pd, byte[] buffer) throws IllegalClassFormatException { 33 return null; 34 } 35 36 private static Instrumentation savedInstrumentation; 37 38 public static void premain(String agentArguments, Instrumentation instrumentation) { 39 System.out.println("ClassFileTransformer.premain() is called"); 40 instrumentation.addTransformer(new AnonVmClassesDuringDumpTransformer(), /*canRetransform=*/true); 41 savedInstrumentation = instrumentation; 42 43 // This will create a Lambda, which will result in some Anonymous VM Classes 44 // being generated. 45 // 46 // Look for something like these in the STDOUT: 47 // ---------------- 48 // ClassFileTransformer.premain() is called 49 // Dumping class files to DUMP_CLASS_FILES/... 50 // dump: DUMP_CLASS_FILES/java/lang/invoke/LambdaForm$MH000.class 51 // dump: DUMP_CLASS_FILES/java/lang/invoke/LambdaForm$MH001.class 52 // Invoked inside a Lambda 53 // ---------------- 54 Runnable r = () -> { 55 System.out.println("Invoked inside a Lambda"); 56 }; 57 r.run(); 58 } 59 60 public static Instrumentation getInstrumentation() { 61 return savedInstrumentation; 62 } 63 64 public static void agentmain(String args, Instrumentation inst) throws Exception { 65 premain(args, inst); 66 } 67 }