xbean-classloader/src/main/java/org/apache/xbean/classloader/JarFileUrlStreamHandler.java

/**
 *
 * Copyright 2005 The Apache Software Foundation
 *
 *  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.apache.xbean.classloader;

import java.io.File;
import java.io.IOException;
import java.io.FileNotFoundException;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLStreamHandler;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;

/**
 * @version $Rev$ $Date: 2006-08-11 01:16:47 +0200 (ven., 11 août 2006) $
 */
public class JarFileUrlStreamHandler extends URLStreamHandler {
    public static URL createUrl(JarFile jarFile, JarEntry jarEntry) throws MalformedURLException {
        return createUrl(jarFile, jarEntry, new File(jarFile.getName()).toURL());
    }

    public static URL createUrl(JarFile jarFile, JarEntry jarEntry, URL codeSource) throws MalformedURLException {
        JarFileUrlStreamHandler handler = new JarFileUrlStreamHandler(jarFile, jarEntry);
        URL url = new URL("jar", "", -1, codeSource + "!/" + jarEntry.getName(), handler);
        handler.setExpectedUrl(url);
        return url;
    }

    private URL expectedUrl;
    private final JarFile jarFile;
    private final JarEntry jarEntry;

    public JarFileUrlStreamHandler(JarFile jarFile, JarEntry jarEntry) {
        if (jarFile == null) throw new NullPointerException("jarFile is null");
        if (jarEntry == null) throw new NullPointerException("jarEntry is null");

        this.jarFile = jarFile;
        this.jarEntry = jarEntry;
    }

    public void setExpectedUrl(URL expectedUrl) {
        if (expectedUrl == null) throw new NullPointerException("expectedUrl is null");
        this.expectedUrl = expectedUrl;
    }

    public URLConnection openConnection(URL url) throws IOException {
        if (expectedUrl == null) throw new IllegalStateException("expectedUrl was not set");

        // the caller copied the URL reusing a stream handler from a previous call
        if (!expectedUrl.equals(url)) {
            // the new url is supposed to be within our context, so it must have a jar protocol
            if (!url.getProtocol().equals("jar")) {
                throw new IllegalArgumentException("Unsupported protocol " + url.getProtocol());
            }

            // split the path at "!/" into the file part and entry part
            String path = url.getPath();
            String[] chunks = path.split("!/", 2);

            // if we only got only one chunk, it didn't contain the required "!/" delimiter
            if (chunks.length == 1) {
                throw new MalformedURLException("Url does not contain a '!' character: " + url);
            }

            String file = chunks[0];
            String entryPath = chunks[1];

            // this handler only supports jars on the local file system
            if (!file.startsWith("file:")) {
                // let the system handler deal with this
                return new URL(url.toExternalForm()).openConnection();
            }
            file = file.substring("file:".length());

            // again the new url is supposed to be within our context so it must reference the same jar file
            if (!jarFile.getName().equals(file)) {
                // let the system handler deal with this
                return new URL(url.toExternalForm()).openConnection();
            }

            // get the entry
            JarEntry newEntry = jarFile.getJarEntry(entryPath);
            if (newEntry == null) {
                throw new FileNotFoundException("Entry not found: " + url);
            }
            return new JarFileUrlConnection(url, jarFile, newEntry);
        }

        return new JarFileUrlConnection(url, jarFile, jarEntry);
    }
}