| // Copyright 2006, 2007, 2008 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.tapestry5.internal.services; |
| |
| import org.apache.commons.codec.binary.Hex; |
| import org.apache.tapestry5.ioc.internal.util.CollectionFactory; |
| import org.apache.tapestry5.ioc.internal.util.InternalUtils; |
| import org.apache.tapestry5.services.ResourceDigestGenerator; |
| |
| import java.io.BufferedInputStream; |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.net.URL; |
| import java.security.MessageDigest; |
| import java.util.Collection; |
| import java.util.Set; |
| |
| /** |
| * Implementation of {@link ResourceDigestGenerator} that generates MD5 digests. |
| */ |
| public class ResourceDigestGeneratorImpl implements ResourceDigestGenerator |
| { |
| private static final int BUFFER_SIZE = 5000; |
| |
| private final Set<String> digestExtensions; |
| |
| public ResourceDigestGeneratorImpl(Collection<String> configuration) |
| { |
| digestExtensions = CollectionFactory.newSet(configuration); |
| } |
| |
| public String generateDigest(URL url) |
| { |
| InputStream stream = null; |
| |
| try |
| { |
| MessageDigest digest = MessageDigest.getInstance("MD5"); |
| |
| stream = new BufferedInputStream(url.openStream()); |
| |
| digestStream(digest, stream); |
| |
| stream.close(); |
| stream = null; |
| |
| byte[] bytes = digest.digest(); |
| char[] encoded = Hex.encodeHex(bytes); |
| |
| return new String(encoded); |
| } |
| catch (Exception ex) |
| { |
| throw new RuntimeException(ex); |
| } |
| finally |
| { |
| InternalUtils.close(stream); |
| } |
| } |
| |
| private void digestStream(MessageDigest digest, InputStream stream) throws IOException |
| { |
| byte[] buffer = new byte[BUFFER_SIZE]; |
| |
| while (true) |
| { |
| int length = stream.read(buffer); |
| |
| if (length < 0) return; |
| |
| digest.update(buffer, 0, length); |
| } |
| } |
| |
| /** |
| * Current implementation is based on the path extension, and a configured list of extensions. |
| */ |
| public boolean requiresDigest(String path) |
| { |
| int dotx = path.lastIndexOf('.'); |
| String extension = path.substring(dotx + 1).toLowerCase(); |
| |
| return digestExtensions.contains(extension); |
| } |
| |
| } |