/*
 * Copyright 2002-2019 the original author or authors.
 *
 * 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
 *
 *      https://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.springframework.cglib.core;

CGLIB GeneratorStrategy variant which exposes the application ClassLoader
as current thread context ClassLoader for the time of class generation.
The ASM ClassWriter in Spring's ASM variant will pick it up when doing
common superclass resolution.
Author:
Juergen Hoeller
Since:
5.2/**
 * CGLIB GeneratorStrategy variant which exposes the application ClassLoader
 * as current thread context ClassLoader for the time of class generation.
 * The ASM ClassWriter in Spring's ASM variant will pick it up when doing
 * common superclass resolution.
 *
 * @author Juergen Hoeller
 * @since 5.2
 */
public class ClassLoaderAwareGeneratorStrategy extends DefaultGeneratorStrategy {

	private final ClassLoader classLoader;

	public ClassLoaderAwareGeneratorStrategy(ClassLoader classLoader) {
		this.classLoader = classLoader;
	}

	@Override
	public byte[] generate(ClassGenerator cg) throws Exception {
		if (this.classLoader == null) {
			return super.generate(cg);
		}

		Thread currentThread = Thread.currentThread();
		ClassLoader threadContextClassLoader;
		try {
			threadContextClassLoader = currentThread.getContextClassLoader();
		}
		catch (Throwable ex) {
			// Cannot access thread context ClassLoader - falling back...
			return super.generate(cg);
		}

		boolean overrideClassLoader = !this.classLoader.equals(threadContextClassLoader);
		if (overrideClassLoader) {
			currentThread.setContextClassLoader(this.classLoader);
		}
		try {
			return super.generate(cg);
		}
		finally {
			if (overrideClassLoader) {
				// Reset original thread context ClassLoader.
				currentThread.setContextClassLoader(threadContextClassLoader);
			}
		}
	}

}