Java Class Path Create getClassPathArchiveContents(final URL resource)

Description

If the resource represents a classpath archive (i.e.

License

BSD License

Parameter

Parameter	Description
resource	the resource from which to retrieve the contents

Return

a list of Strings containing the names of every nested resource found in this resource.

Declaration

public static List<String> getClassPathArchiveContents(final URL resource) 

Method Source Code

//package com.java2s;
//License from project: BSD License 

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;

import java.net.URL;

import java.net.URLDecoder;
import java.util.ArrayList;

import java.util.Enumeration;
import java.util.List;

import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;

public class Main {
    /**//from w  w w . java 2  s . com
     * All archive files start with this prefix.
     */
    private static final String ARCHIVE_PREFIX = "jar:";
    private static final String URL_DECODE_ENCODING = "UTF-8";

    /**
     * If the <code>resource</code> represents a classpath archive (i.e. jar, zip, etc), this method will retrieve all
     * contents from that resource as a List of relative paths (relative to the archive base). Otherwise an empty List
     * will be returned.
     *
     * @param resource the resource from which to retrieve the contents
     * @return a list of Strings containing the names of every nested resource found in this resource.
     */
    public static List<String> getClassPathArchiveContents(final URL resource) {
        final List<String> contents = new ArrayList<String>();
        if (isArchive(resource)) {
            final ZipFile archive = getArchive(resource);
            if (archive != null) {
                for (final Enumeration<? extends ZipEntry> entries = archive.entries(); entries
                        .hasMoreElements();) {
                    final ZipEntry entry = entries.nextElement();
                    contents.add(entry.getName());
                }
                try {
                    archive.close();
                } catch (IOException ex) {
                    // Ignore
                }
            }
        }
        return contents;
    }

    /**
     * Returns true/false on whether or not this <code>resource</code> represents an archive or not (i.e. jar, or zip,
     * etc).
     *
     * @param resource
     * @return true if its an archive, false otherwise.
     */
    public static boolean isArchive(final URL resource) {
        return resource != null && resource.toString().startsWith(ARCHIVE_PREFIX);
    }

    /**
     * If this <code>resource</code> is an archive file, it will return the resource as an archive.
     *
     * @param resource
     * @return the archive as a ZipFile
     */
    public static ZipFile getArchive(final URL resource) {
        try {
            ZipFile archive = null;
            if (resource != null) {
                String resourceUrl = resource.toString();
                resourceUrl = resourceUrl.replaceFirst(ARCHIVE_PREFIX, "");
                final int entryPrefixIndex = resourceUrl.indexOf('!');
                if (entryPrefixIndex != -1) {
                    resourceUrl = resourceUrl.substring(0, entryPrefixIndex);
                }
                resourceUrl = URLDecoder.decode(new URL(resourceUrl).getFile(), URL_DECODE_ENCODING);
                File zipFile = new File(resourceUrl);
                if (zipFile.exists()) {
                    archive = new ZipFile(resourceUrl);
                } else {
                    // ZipFile doesn't give enough detail about missing file
                    throw new FileNotFoundException("ResourceUtils.getArchive " + resourceUrl + " NOT FOUND.");
                }
            }
            return archive;
        }
        // Don't unnecessarily wrap RuntimeException
        catch (final RuntimeException ex) {
            throw ex;
        }
        // But don't require Exception declaration either.
        catch (final Throwable throwable) {
            throw new RuntimeException(throwable);
        }
    }
}

Related

1. getClassBasePath(URL classUrl, Class clazz)
2. getClasspathResourceURL(String resourceName)
3. getClasspathUrl(final Class aClass, final String aPath)
4. getClasspathURL(final String name)
5. getClasspathURLs(String classpath)