Java example source code file (Asmator.java)

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Java - Java tags/keywords

asmator, classreader, classvisitor, classwriter, methodvisitor, string

The Asmator.java Java example source code

/*
 * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

import jdk.internal.org.objectweb.asm.*;

class Asmator {
    static byte[] fixup(byte[] buf) throws java.io.IOException {
        ClassReader cr = new ClassReader(buf);
        ClassWriter cw = new ClassWriter(0);
        ClassVisitor cv = new ClassVisitor(Opcodes.ASM4, cw) {
            public MethodVisitor visitMethod(
                final int access,
                final String name,
                final String desc,
                final String signature,
                final String[] exceptions)
            {
                MethodVisitor mv = super.visitMethod(access,
                        name,
                        desc,
                        signature,
                        exceptions);
                if (mv == null)  return null;
                if (name.equals("callme")) {
                    // make receiver go dead!
                    mv.visitInsn(Opcodes.ACONST_NULL);
                    mv.visitVarInsn(Opcodes.ASTORE, 0);
                }
                return mv;
            }
        };
        cr.accept(cv, 0);
        return cw.toByteArray();
    }
}