PublicStaticFieldReferenceReplacer.java

package org.coldswap.asm.field;

import org.coldswap.asm.FieldBox;
import org.coldswap.asm.ReferenceReplacer;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.tree.*;

import java.util.Iterator;
import java.util.List;

/**
 * (C) Copyright 2013 Faur Ioan-Aurel.
 * <p/>
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the GNU Lesser General Public License
 * (LGPL) version 2.1 which accompanies this distribution, and is available at
 * http://www.gnu.org/licenses/lgpl-2.1.html
 * <p/>
 * This library 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
 * Lesser General Public License for more details.
 * <p/>
 * Contributors:
 * faur
 * <p/>
 * Created at:
 * 4:57 PM       4/30/13
 */

public class PublicStaticFieldReferenceReplacer extends FieldBox implements ReferenceReplacer {


    /**
     * Constructs a container for a field reference that should be searched and replaced.
     *
     * @param oldClass       the old class reference.
     * @param fieldToReplace the field that should be instrumented.
     * @param newClass       the new class reference for the field.
     */
    public PublicStaticFieldReferenceReplacer(String oldClass, FieldNode fieldToReplace, String newClass) {
        super(oldClass, fieldToReplace, newClass);
    }

    @SuppressWarnings("unchecked")
    @Override
    public int findAndReplace(ClassNode classNode) {
        int counter = 0;
        List<MethodNode> methodNodes = classNode.methods;
        for (MethodNode method : methodNodes) {
            InsnList inst = method.instructions;
            Iterator iter = inst.iterator();
            while (iter.hasNext()) {
                AbstractInsnNode absIns = (AbstractInsnNode) iter.next();
                int opcode = absIns.getOpcode();
                // check if instruction is GETSTATIC or PUTSTATIC
                if (opcode == Opcodes.GETSTATIC) {
                    // get type
                    if (absIns.getType() == AbstractInsnNode.FIELD_INSN) {
                        final Boolean[] foundField = {false};
                        absIns.accept(new MethodVisitor(Opcodes.ASM5) {
                            @Override
                            public void visitFieldInsn(int i, String s, String s2, String s3) {
                                if (oldClass.equals(s) && fieldToReplace.name.equals(s2)) {
                                    foundField[0] = true;
                                }
                                super.visitFieldInsn(i, s, s2, s3);
                            }
                        });
                        if (foundField[0]) {
                            inst.set(absIns, new FieldInsnNode(Opcodes.GETSTATIC, newClass, fieldToReplace.name, fieldToReplace.desc));
                            counter++;
                        }
                    }
                } else if (opcode == Opcodes.PUTSTATIC) {
                    if (absIns.getType() == AbstractInsnNode.FIELD_INSN) {
                        final Boolean[] foundField = {false};
                        absIns.accept(new MethodVisitor(Opcodes.ASM5) {
                            @Override
                            public void visitFieldInsn(int i, String s, String s2, String s3) {
                                if (oldClass.equals(s) && fieldToReplace.name.equals(s2)) {
                                    foundField[0] = true;
                                }
                                super.visitFieldInsn(i, s, s2, s3);
                            }
                        });
                        if (foundField[0]) {
                            inst.set(absIns, new FieldInsnNode(Opcodes.PUTSTATIC, newClass, fieldToReplace.name, fieldToReplace.desc));
                            counter++;
                        }
                    }
                }
            }
        }
        return counter;
    }
}