HelloClassPool.java

/*
 * JBoss, Home of Professional Open Source
 * Copyright 2015, Red Hat, Inc. and/or its affiliates, and individual
 * contributors by the @authors tag. See the copyright.txt in the
 * distribution for a full listing of individual 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 hello.server.transformation;

import java.util.HashSet;
import java.util.Set;

import javassist.ClassPool;
import javassist.CtClass;
import javassist.LoaderClassPath;
import javassist.NotFoundException;

/**
 * A {@link ClassPool} that supports adding classpath's through {@link ClassLoader} objects.<br>
 * <br>
 *
 * @author <a href="mailto:moelholm@gmail.com">Nicky Moelholm</a>
 */
public class HelloClassPool extends ClassPool {

    // ------------------------------------------------------------------------
    // Static fields
    // ------------------------------------------------------------------------

    private static final Set<ClassLoader> loaders = new HashSet<ClassLoader>();

    // ------------------------------------------------------------------------
    // Constructors
    // ------------------------------------------------------------------------

    public HelloClassPool() {
        super(null);
        appendSystemPath();
    }

    // ------------------------------------------------------------------------
    // Public API
    // ------------------------------------------------------------------------

    public void addClassLoaderClassPath(ClassLoader cl) {
        synchronized (loaders) {
            if (!loaders.contains(cl)) {
                insertClassPath(new LoaderClassPath(cl));
                loaders.add(cl);
            }
        }
    }

    // ------------------------------------------------------------------------
    // Specialization of the normal ClassPool behavior
    // ------------------------------------------------------------------------

    /**
     * This method can cause deadlocks in the parent pool. Hence it is overwritten here without the <code>synchronized</code>
     * modifier.
     */
    @Override
    protected CtClass get0(String classname, boolean useCache) throws NotFoundException {

        CtClass clazz = null;

        if (useCache) {
            clazz = getCached(classname);
            if (clazz != null) {
                return clazz;
            }
        }

        clazz = createCtClass(classname, useCache);

        if (clazz != null) {

            if (useCache) {
                cacheCtClass(clazz.getName(), clazz, false);
            }

            return clazz;
        }

        return clazz;
    }
}