org.apache.hadoop.util.ClassUtil.java Source code

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Here is the source code for org.apache.hadoop.util.ClassUtil.java

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/*
 * 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.hadoop.util;

import java.io.IOException;
import java.net.URL;
import java.net.URLDecoder;
import java.util.Enumeration;

import org.apache.hadoop.classification.InterfaceAudience;

@InterfaceAudience.Private
public class ClassUtil {
    /** 
     * Find a jar that contains a class of the same name, if any.
     * It will return a jar file, even if that is not the first thing
     * on the class path that has a class with the same name.
     * 
     * @param clazz the class to find.
     * @return a jar file that contains the class, or null.
     * @throws IOException
     */
    public static String findContainingJar(Class<?> clazz) {
        ClassLoader loader = clazz.getClassLoader();
        String classFile = clazz.getName().replaceAll("\\.", "/") + ".class";
        try {
            for (final Enumeration<URL> itr = loader.getResources(classFile); itr.hasMoreElements();) {
                final URL url = itr.nextElement();
                if ("jar".equals(url.getProtocol())) {
                    String toReturn = url.getPath();
                    if (toReturn.startsWith("file:")) {
                        toReturn = toReturn.substring("file:".length());
                    }
                    toReturn = URLDecoder.decode(toReturn, "UTF-8");
                    return toReturn.replaceAll("!.*$", "");
                }
            }
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        return null;
    }
}