org.springsource.loaded.agent.NonFinalizer Maven / Gradle / Ivy
/*
* Copyright 2010-2012 VMware and contributors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springsource.loaded.agent;
import java.lang.reflect.Modifier;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.FieldVisitor;
import org.springsource.loaded.Constants;
/**
* Makes a field or fields non final.
*
* @author Andy Clement
* @since 0.7.0
*/
public class NonFinalizer extends ClassVisitor implements Constants {
private String fieldname;
/**
* This ClassAdapter will visit a class and within the constructors it will add a call to the specified method
* (assumed static) just before each constructor returns. The target of the call should be a collecting method that
* will likely do something with the instances later on class reload.
*
* @param fieldname the name of the field to be made non final
*/
public NonFinalizer(String fieldname) {
super(ASM5, new ClassWriter(0)); // TODO review 0 here
this.fieldname = fieldname;
}
public byte[] getBytes() {
return ((ClassWriter) cv).toByteArray();
}
@Override
public FieldVisitor visitField(int access, String name, String desc, String signature, Object value) {
if (name.equals(fieldname)) {
return super.visitField(access & (~Modifier.FINAL), name, desc, signature, value);
}
else {
return super.visitField(access, name, desc, signature, value);
}
}
// public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) {
// if (name.equals("")) {
// MethodVisitor mv = super.visitMethod(access, name, desc, signature, exceptions);
// return new ConstructorAppender(mv);
// } else {
// return super.visitMethod(access, name, desc, signature, exceptions);
// }
// }
/**
* This constructor appender includes a couple of instructions at the end of each constructor it is asked to visit.
* It recognizes the end by observing a RETURN instruction. The instructions are inserted just before the RETURN.
*/
// class ConstructorAppender extends MethodAdapter implements Constants {
//
// public ConstructorAppender(MethodVisitor mv) {
// super(mv);
// }
//
// @Override
// public void visitInsn(int opcode) {
// if (opcode == RETURN) {
// mv.visitVarInsn(ALOAD, 0);
// mv.visitMethodInsn(INVOKESTATIC, calleeOwner, calleeName, "(Ljava/lang/Object;)V");
// }
// super.visitInsn(opcode);
// }
//
// }
}