ResourcePaths.java

/*
 * Copyright 2017 OmniFaces
 *
 * 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.omnifaces.util;

import java.util.HashSet;
import java.util.Set;

import javax.servlet.ServletContext;

/**
 * Utility class for working with (Servlet) resource paths, providing methods to handle their
 * prefixes, extensions etc.
 *
 * @author Arjan Tijms
 * @since 1.4
 */
public final class ResourcePaths {

	private ResourcePaths() {
		// Hide constructor
	}

	/**
	 * Checks if the given resource path obtained from {@link ServletContext#getResourcePaths(String)} represents a
	 * directory.
	 *
	 * @param resourcePath
	 *            the resource path to check
	 * @return true if the resource path represents a directory, false otherwise
	 */
	public static boolean isDirectory(final String resourcePath) {
		return resourcePath.endsWith("/");
	}

	/**
	 * Strips the given prefix path from the given resource path if any.
	 *
	 * @param prefix The prefix to be stripped.
	 * @param resource The resource to strip the prefix from.
	 * @return the resource without the prefix path, or as-is if it didn't start with this prefix.
	 */
	public static String stripPrefixPath(final String prefix, final String resource) {
		String normalizedResource = resource;
		if (normalizedResource.startsWith(prefix)) {
			normalizedResource = normalizedResource.substring(prefix.length() - 1);
		}

		return normalizedResource;
	}

	/**
	 * Strips the trailing slash(es) from the given resource path if any.
	 *
	 * @param resource The resource to strip the trailing slash from.
	 * @return the resource without the trailing slash, or as-is if it didn't have a trailing slash.
	 * @since 2.6
	 */
	public static String stripTrailingSlash(String resource) {
		return resource.endsWith("/") ? stripTrailingSlash(resource.substring(0, resource.length() - 1)) : resource;
	}

	/**
	 * Strips the extension from a resource if any. This extension is defined as everything after the last occurrence of
	 * a period, including the period itself. E.g. input "index.xhtml" will return "index".
	 *
	 * @param resource The resource to strip the extension from.
	 * @return the resource without its extension, of as-is if it doesn't have an extension.
	 */
	public static String stripExtension(final String resource) {
		String normalizedResource = resource;
		int lastPeriod = resource.lastIndexOf('.');
		if (lastPeriod != -1) {
			normalizedResource = resource.substring(0, lastPeriod);
		}

		return normalizedResource;
	}

	/**
	 * Gets the extension of a resource if any. This extension is defined as everything after the last occurrence of a
	 * period, including the period itself. E.g. input "index.xhtml" will return ".xhtml'.
	 *
	 * @param resource The resource to get the extension from.
	 * @return the extension of the resource, or null if it doesn't have an extension.
	 */
	public static String getExtension(final String resource) {
		String extension = null;
		int lastPeriod = resource.lastIndexOf('.');
		if (lastPeriod != -1) {
			extension = resource.substring(lastPeriod);
		}

		return extension;
	}

	public static boolean isExtensionless(final String viewId) {
		return viewId != null && !viewId.contains(".");
	}

	/**
	 * Filters away every resource in the given set that has an extension.
	 *
	 * @param resources A set of resources to be filtered
	 * @return A set where no resource has an extension. May be empty, but never null.
	 */
	public static Set<String> filterExtension(Set<String> resources) {
		Set<String> filteredResources = new HashSet<>();
		for (String resource : resources) {
			if (isExtensionless(resource)) {
				filteredResources.add(resource);
			}
		}

		return filteredResources;
	}

}