org.impalaframework.spring.classloader.CustomURLClassLoader.java Source code

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Here is the source code for org.impalaframework.spring.classloader.CustomURLClassLoader.java

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/*
 * Copyright 2007-2010 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
 * 
 * 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.impalaframework.spring.classloader;

import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public class CustomURLClassLoader extends URLClassLoader {

    private static final Log logger = LogFactory.getLog(CustomURLClassLoader.class);

    private Map<String, Class<?>> loadedClasses = new ConcurrentHashMap<String, Class<?>>();

    public CustomURLClassLoader(File location) throws MalformedURLException {

        super(new URL[] { location.toURI().toURL() }, CustomURLClassLoader.class.getClassLoader());
    }

    public CustomURLClassLoader(ClassLoader parent, File location) throws MalformedURLException {
        super(new URL[] { location.toURI().toURL() }, parent);
    }

    public Class<?> loadClass(String className) throws ClassNotFoundException {

        try {
            Class<?> parentClass = getParent().loadClass(className);

            if (logger.isDebugEnabled())
                logger.debug("Returning system class: " + parentClass);

            return parentClass;
        } catch (Exception e) {
        }

        try {

            Class<?> loadedClass = loadedClasses.get(className);
            if (loadedClass != null) {
                if (logger.isDebugEnabled())
                    logger.debug("Returning already loaded custom class: " + className);

                return loadedClass;
            }

            Class<?> result = findClass(className);

            loadedClasses.put(className, result);

            return result;

        } catch (Exception e) {
        }

        if (logger.isDebugEnabled())
            logger.debug("Class not found: " + className);
        throw new ClassNotFoundException(className);

    }
}