ClassLoaderResourceProvider.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.sling.launchpad.base.impl;

import java.io.IOException;
import java.io.InputStream;
import java.net.JarURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
import java.util.regex.Pattern;

import org.apache.sling.launchpad.api.LaunchpadContentProvider;

/**
 * The <code>ClassLoaderResourceProvider</code>
 */
public class ClassLoaderResourceProvider implements LaunchpadContentProvider {

    private final ClassLoader classLoader;

    public ClassLoaderResourceProvider(ClassLoader classLoader) {
        this.classLoader = (classLoader != null)
                ? classLoader
                : this.getClass().getClassLoader();
    }

    @Override
    public Iterator<String> getChildren(String path) {
        List<String> children;

        // Guard against extra trailing slashes
        if(path.endsWith("/") && path.length() > 1) {
            path = path.substring(0, path.length()-1);
        }

        URL url = this.classLoader.getResource(path);
        if (url != null) {
            Pattern pathPattern = Pattern.compile("^" + path + "/[^/]+/?$");

            children = new ArrayList<String>();
            try {
                URLConnection conn = url.openConnection();
                if (conn instanceof JarURLConnection) {
                    JarFile jar = ((JarURLConnection) conn).getJarFile();
                    Enumeration<JarEntry> entries = jar.entries();
                    while (entries.hasMoreElements()) {
                        String entry = entries.nextElement().getName();
                        if (pathPattern.matcher(entry).matches()) {
                            children.add(entry);
                        }
                    }
                }
            } catch (IOException ioe) {
                // ignore for now
            }
        } else {
            children = Collections.emptyList();
        }

        return children.iterator();
    }

    @Override
    public URL getResource(String path) {
        // ensure path
        if (path == null || path.length() == 0) {
            return null;
        }

        // remove leading slash
        if (path.charAt(0) == '/') {
            path = path.substring(1);
        }

        return (this.classLoader != null) ? this.classLoader.getResource(path) : null;
    }

    @Override
    public InputStream getResourceAsStream(String path) {
        URL res = this.getResource(path);
        if (res != null) {
            try {
                return res.openStream();
            } catch (IOException ioe) {
                // ignore this one
            }
        }

        // no resource
        return null;

    }

}