org.akhikhl.gretty.TomcatEmbeddedWebappClassLoader Maven / Gradle / Ivy

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/*
 * Gretty
 *
 * Copyright (C) 2013-2015 Andrey Hihlovskiy and contributors.
 *
 * See the file "LICENSE" for copying and usage permission.
 * See the file "CONTRIBUTORS" for complete list of contributors.
 */
package org.akhikhl.gretty;

import java.net.URL;
import org.apache.catalina.loader.WebappClassLoader;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * The code was copied from:
 * https://github.com/spring-projects/spring-boot/blob/master/spring-boot/src/main/java/org/springframework/boot/context/embedded/tomcat/TomcatEmbeddedWebappClassLoader.java
 * Changes compared to original version: replaced logging to slf4j.
 *
 * @author akhikhl
 */
public class TomcatEmbeddedWebappClassLoader extends WebappClassLoader {

	private static final Logger log = LoggerFactory.getLogger(TomcatEmbeddedWebappClassLoader.class);

	public TomcatEmbeddedWebappClassLoader() {
	}

	public TomcatEmbeddedWebappClassLoader(ClassLoader parent) {
		super(parent);
	}

	@Override
	public synchronized Class loadClass(String name, boolean resolve) throws ClassNotFoundException {

		Class resultClass = null;

		// Check local class caches
		resultClass = (resultClass == null ? findLoadedClass0(name) : resultClass);
		resultClass = (resultClass == null ? findLoadedClass(name) : resultClass);
		if (resultClass != null)
			return resolveIfNecessary(resultClass, resolve);

		// Check security
		checkPackageAccess(name);

		// Perform the actual load
		boolean delegateLoad = (this.delegate || filter(name));

		if (delegateLoad)
			resultClass = (resultClass == null ? loadFromParent(name) : resultClass);

		resultClass = (resultClass == null ? findClassIgnoringNotFound(name) : resultClass);

		if (!delegateLoad)
			resultClass = (resultClass == null ? loadFromParent(name) : resultClass);

		if (resultClass == null)
			throw new ClassNotFoundException(name);

		return resolveIfNecessary(resultClass, resolve);
	}

	private Class resolveIfNecessary(Class resultClass, boolean resolve) {
		if (resolve)
			resolveClass(resultClass);
		return (resultClass);
	}

	@Override
	protected void addURL(URL url) {
		// Ignore URLs added by the Tomcat 8 implementation (see gh-919)
    log.trace("Ignoring request to add {} to the tomcat classloader", url);
	}

	private Class loadFromParent(String name) {
		if (this.parent == null)
			return null;
		try {
			return Class.forName(name, false, this.parent);
		}
		catch (ClassNotFoundException ex) {
			return null;
		}
	}

	private Class findClassIgnoringNotFound(String name) {
		try {
			return findClass(name);
		}
		catch (ClassNotFoundException ex) {
			return null;
		}
	}

	private void checkPackageAccess(String name) throws ClassNotFoundException {
		if (this.securityManager != null && name.lastIndexOf('.') >= 0) {
			try {
				this.securityManager.checkPackageAccess(name.substring(0, name.lastIndexOf('.')));
			}
			catch (SecurityException ex) {
				throw new ClassNotFoundException("Security Violation, attempt to use Restricted Class: " + name, ex);
			}
		}
	}
}