org.springframework.instrument.classloading.InstrumentableClassLoaderFactoryBean.java Source code

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Here is the source code for org.springframework.instrument.classloading.InstrumentableClassLoaderFactoryBean.java

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/*
 * Copyright 2002-2006 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.springframework.instrument.classloading;

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

import org.springframework.beans.factory.FactoryBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils;

/**
 * Retrieves a class loader from the context class loader using the className property.
 * It will traverse the class loader hierarchy and analyze the class loader,
 * interfaces and superclasses.
 *
 * @author Costin Leau
 * @since 2.0
 */
public class InstrumentableClassLoaderFactoryBean implements FactoryBean, InitializingBean {

    private final Log logger = LogFactory.getLog(getClass());

    private String className;

    /** Loose reference to avoid class loading problems */
    private ClassLoader classLoader;

    public void setClassName(String className) {
        this.className = className;
    }

    public void afterPropertiesSet() {
        if (!StringUtils.hasText(this.className)) {
            throw new IllegalArgumentException("className is required");
        }

        ClassLoader loader = ClassUtils.getDefaultClassLoader();

        // parse class loading hierarchy
        for (Class clazz = loader.getClass(); loader != null
                && this.classLoader == null; loader = loader.getParent()) {
            // check class itself
            if (analyzeClasses(loader, clazz)) {
                return;
            }
            // check interfaces
            if (analyzeClasses(loader, clazz.getInterfaces())) {
                return;
            }
            // check superclasses
            for (Class superClass = clazz.getSuperclass(); superClass != Object.class
                    && superClass != null; superClass = clazz.getSuperclass())
                if (analyzeClasses(loader, superClass)) {
                    return;
                }
        }

        throw new IllegalArgumentException(this.className + " was not found in the current classloader hierarchy - "
                + "see docs on how to use instrumented classloaders inside various environments");
    }

    protected boolean analyzeClasses(ClassLoader loader, Class... classes) {
        boolean debug = logger.isDebugEnabled();
        for (Class clazz : classes) {
            if (debug) {
                logger.debug("Analyzing class: " + clazz.getName());
            }
            if (this.className.equals(clazz.getName())) {
                if (debug) {
                    logger.debug(this.className + " found! Using class loader: " + loader);
                }
                this.classLoader = loader;
                return true;
            }
        }
        return false;
    }

    public Object getObject() {
        return this.classLoader;
    }

    public Class getObjectType() {
        return ClassLoader.class;
    }

    public boolean isSingleton() {
        return false;
    }

}