tomcat-ext/src/main/java/org/apache/kylin/ext/CustomizedWebappClassloader.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.
 */

package org.apache.kylin.ext;

import org.apache.catalina.loader.ParallelWebappClassLoader;

/**
 * simple extension to standard ParallelWebappClassLoader
 * the only difference is that CustomizedWebappClassloader is able to delegate more packages
 * to parent classloaders
 */
public class CustomizedWebappClassloader extends ParallelWebappClassLoader {
    /**
     * Set of package names which are not allowed to be loaded from a webapp
     * class loader without delegating first.
     */
    private static final String[] packageTriggers = { "org.slf4j" };

    public CustomizedWebappClassloader() {
    }

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

    /**
     * Filter classes.
     *
     * @param name class name
     * @return true if the class should be filtered
     */
    protected boolean filter(String name) {
        if (name == null)
            return false;

        // Looking up the package
        String packageName = null;
        int pos = name.lastIndexOf('.');
        if (pos != -1)
            packageName = name.substring(0, pos);
        else
            return false;

        for (int i = 0; i < packageTriggers.length; i++) {
            if (packageName.startsWith(packageTriggers[i]))
                return true;
        }

        return super.filter(name);
    }
}