commons-bcel-master/src/examples/Id.java
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */

import org.apache.bcel.Repository;
import org.apache.bcel.classfile.ClassParser;
import org.apache.bcel.classfile.Field;
import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.classfile.Method;
import org.apache.bcel.generic.ClassGen;
import org.apache.bcel.generic.FieldGen;
import org.apache.bcel.generic.MethodGen;

/**
 * Test BCEL if an input file is identical to the outfile generated with BCEL. Of course there may some small
 * differences, e.g., because BCEL generates local variable tables by default.
 *
 * Try to:
 *
 * <pre>
 * % java Id <someclass> % java listclass -code <someclass> &gt; foo % java listclass -code <someclass>.clazz &gt; bar %
 * diff foo bar | more
 *
 * <pre>
 */
public class Id {

    public static void main(final String[] argv) throws Exception {
        JavaClass clazz;

        if ((clazz = Repository.lookupClass(argv[0])) == null) {
            clazz = new ClassParser(argv[0]).parse(); // May throw IOException
        }

        final ClassGen cg = new ClassGen(clazz);

        for (final Method method : clazz.getMethods()) {
            final MethodGen mg = new MethodGen(method, cg.getClassName(), cg.getConstantPool());
            cg.replaceMethod(method, mg.getMethod());
        }

        for (final Field field : clazz.getFields()) {
            final FieldGen fg = new FieldGen(field, cg.getConstantPool());
            cg.replaceField(field, fg.getField());
        }

        cg.getJavaClass().dump(clazz.getClassName() + ".clazz");
    }
}
