org.conqat.lib.commons.filesystem.PathBasedContentProviderBase Maven / Gradle / Ivy

Show more of this group Show more artifacts with this name
Show all versions of teamscale-lib-commons Show documentation
Provides common utility functions
There is a newer version: 2024.7.2
Show newest version
/*
 * Copyright (c) CQSE GmbH
 *
 * 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.conqat.lib.commons.filesystem;

import java.io.Closeable;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collection;

/**
 * Base class for objects that provide access to the content of various elements using a path for
 * access. This basically abstracts the differences between plain directories and ZIP files
 * (containing multiple entries).
 */
public abstract class PathBasedContentProviderBase implements Closeable {

	/**
	 * Returns the relative paths to all available elements that carry content. These correspond to file
	 * names or names of ZIP file entries. The returned paths are guaranteed to use a forward slash as
	 * the path separator.
	 */
	public abstract Collection getPaths() throws IOException;

	/**
	 * {@inheritDoc}
	 * 
	 * This closes the content provider itself, i.e. after closing, no new streams may be opened.
	 * Whether existing streams are closed depends on the implementation, but it is recommended to close
	 * any streams returned from {@link #openStream(String)} yourself and to not use any of these
	 * streams after calling this method.
	 */
	@Override
	public abstract void close() throws IOException;

	/**
	 * Opens a stream to the element identified by the given path. This should be one of the paths
	 * returned by the {@link #getPaths()} method. The returned stream must be closed by the caller.
	 */
	public abstract InputStream openStream(String relativePath) throws IOException;

	/** Returns all paths starting with a given prefix. */
	public Collection getPathsWithPrefix(String prefix) throws IOException {
		Collection result = new ArrayList<>();
		for (String path : getPaths()) {
			if (path.startsWith(prefix)) {
				result.add(path);
			}
		}
		return result;
	}

	/**
	 * Creates a suitable provider for a file. This works for directories as well as ZIP/JAR files. The
	 * returned provider has to be closed at the end.
	 *
	 * @throws IOException
	 *             if accessing the file fails or the file is not of suitable format (i.e. no directory
	 *             or ZIP file).
	 */
	public static PathBasedContentProviderBase createProvider(File file) throws IOException {
		if (file.isDirectory()) {
			return new DirectoryContentProvider(file);
		}

		return new ZipContentProvider(new ZipFile(file));
	}
}