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Jodd Util
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// Copyright (c) 2003-present, Jodd Team (http://jodd.org)
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.

package jodd.util;

import jodd.io.IOUtil;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;

public class ResourcesUtil {

	// ---------------------------------------------------------------- get resource

	/**
	 * Retrieves given resource as URL.
	 * @see #getResourceUrl(String, ClassLoader)
	 */
	public static URL getResourceUrl(final String resourceName) {
		return getResourceUrl(resourceName, null);
	}

	/**
	 * Retrieves given resource as URL. Resource is always absolute and may
	 * starts with a slash character.
	 * 
	 * Resource will be loaded using class loaders in the following order:
	 * 

	 * {@link Thread#getContextClassLoader() Thread.currentThread().getContextClassLoader()}
	 * {@link Class#getClassLoader() ClassLoaderUtil.class.getClassLoader()}
	 * if callingClass is provided: {@link Class#getClassLoader() callingClass.getClassLoader()}
	 * 
	 */
	public static URL getResourceUrl(String resourceName, final ClassLoader classLoader) {

		if (resourceName.startsWith("/")) {
			resourceName = resourceName.substring(1);
		}

		URL resourceUrl;

		// try #1 - using provided class loader
		if (classLoader != null) {
			resourceUrl = classLoader.getResource(resourceName);
			if (resourceUrl != null) {
				return resourceUrl;
			}
		}

		// try #2 - using thread class loader
		final ClassLoader currentThreadClassLoader = Thread.currentThread().getContextClassLoader();
		if ((currentThreadClassLoader != null) && (currentThreadClassLoader != classLoader)) {
			resourceUrl = currentThreadClassLoader.getResource(resourceName);
			if (resourceUrl != null) {
				return resourceUrl;
			}
		}

		// try #3 - using caller classloader, similar as Class.forName()
		final Class callerClass = ClassUtil.getCallerClass(2);
		final ClassLoader callerClassLoader = callerClass.getClassLoader();

		if ((callerClassLoader != classLoader) && (callerClassLoader != currentThreadClassLoader)) {
			resourceUrl = callerClassLoader.getResource(resourceName);
			if (resourceUrl != null) {
				return resourceUrl;
			}
		}

		return null;
	}

	// ---------------------------------------------------------------- get resource string

	public static String getResourceAsString(final String resourceName) throws IOException {
		final InputStream inputStream = getResourceAsStream(resourceName);
		try {
			final char[] data = IOUtil.readChars(inputStream);
			return new String(data);
		}
		finally {
			IOUtil.close(inputStream);
		}
	}

	// ---------------------------------------------------------------- get resource stream

	/**
	 * Opens a resource of the specified name for reading.
	 * @see #getResourceAsStream(String, ClassLoader)
	 */
	public static InputStream getResourceAsStream(final String resourceName) throws IOException {
		return getResourceAsStream(resourceName, null);
	}

	/**
	 * Opens a resource of the specified name for reading.
	 * @see #getResourceUrl(String, ClassLoader)
	 */
	public static InputStream getResourceAsStream(final String resourceName, final ClassLoader callingClass) throws IOException {
		final URL url = getResourceUrl(resourceName, callingClass);
		if (url != null) {
			return url.openStream();
		}
		return null;
	}

	/**
	 * Opens a resource of the specified name for reading. Controls caching,
	 * that is important when the same jar is reloaded using custom classloader.
	 */
	public static InputStream getResourceAsStream(final String resourceName, final ClassLoader callingClass, final boolean useCache) throws IOException {
		final URL url = getResourceUrl(resourceName, callingClass);
		if (url != null) {
			final URLConnection urlConnection = url.openConnection();
			urlConnection.setUseCaches(useCache);
			return urlConnection.getInputStream();
		}
		return null;
	}


}