impl/src/main/java/org/apache/myfaces/config/util/JarUtils.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.myfaces.config.util;

import java.io.IOException;
import java.net.JarURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.util.jar.JarFile;

/**
 *
 * @author Leonardo Uribe
 */
public class JarUtils
{

    public static JarFile getJarFile(URL url) throws IOException
    {
        URLConnection conn = url.openConnection();
        conn.setUseCaches(false);
        conn.setDefaultUseCaches(false);

        JarFile jarFile;
        if (conn instanceof JarURLConnection)
        {
            jarFile = ((JarURLConnection) conn).getJarFile();
        }
        else
        {
            jarFile = _getAlternativeJarFile(url);
        }
        return jarFile;
    }
    
    /**
     * taken from org.apache.myfaces.view.facelets.util.Classpath
     * 
     * For URLs to JARs that do not use JarURLConnection - allowed by the servlet spec - attempt to produce a JarFile
     * object all the same. Known servlet engines that function like this include Weblogic and OC4J. This is not a full
     * solution, since an unpacked WAR or EAR will not have JAR "files" as such.
     */
    private static JarFile _getAlternativeJarFile(URL url) throws IOException
    {
        String urlFile = url.getFile();

        // Trim off any suffix - which is prefixed by "!/" on Weblogic
        int separatorIndex = urlFile.indexOf("!/");

        // OK, didn't find that. Try the less safe "!", used on OC4J
        if (separatorIndex == -1)
        {
            separatorIndex = urlFile.indexOf('!');
        }

        if (separatorIndex != -1)
        {
            String jarFileUrl = urlFile.substring(0, separatorIndex);
            // And trim off any "file:" prefix.
            if (jarFileUrl.startsWith("file:"))
            {
                jarFileUrl = jarFileUrl.substring("file:".length());
            }

            return new JarFile(jarFileUrl);
        }

        return null;
    }

}