001// Copyright 2013 The Apache Software Foundation 002// 003// Licensed under the Apache License, Version 2.0 (the "License"); 004// you may not use this file except in compliance with the License. 005// You may obtain a copy of the License at 006// 007// http://www.apache.org/licenses/LICENSE-2.0 008// 009// Unless required by applicable law or agreed to in writing, software 010// distributed under the License is distributed on an "AS IS" BASIS, 011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 012// See the License for the specific language governing permissions and 013// limitations under the License. 014 015package org.apache.tapestry5.internal.services.assets; 016 017import org.apache.commons.lang3.StringUtils; 018import org.apache.tapestry5.internal.services.ResourceStreamer; 019import org.apache.tapestry5.ioc.Resource; 020 021import java.io.IOException; 022 023/** 024 * Utility used by {@link org.apache.tapestry5.services.assets.AssetRequestHandler} implementations 025 * where the first folder in the extra path is actually a computed checksum of the resource's content. 026 * 027 * @since 5.4 028 */ 029public class ChecksumPath 030{ 031 private static final String NON_EXISTING_RESOURCE = "_________________________"; 032 033 public final String checksum; 034 035 public final String resourcePath; 036 037 private final ResourceStreamer streamer; 038 039 public ChecksumPath(ResourceStreamer streamer, String baseFolder, String extraPath) 040 { 041 this.streamer = streamer; 042 int slashx = extraPath.indexOf('/'); 043 044 checksum = slashx >= 0 ? extraPath.substring(0, slashx) : null; 045 046 String morePath = extraPath.substring(slashx + 1); 047 048 if (StringUtils.isNotBlank(morePath)) { 049 resourcePath = baseFolder == null 050 ? morePath 051 : baseFolder + "/" + morePath; 052 } 053 else { 054 // When we only have something which looks like a checksum but no actual path. 055 // For example, /assets/META-INF/ 056 resourcePath = NON_EXISTING_RESOURCE; 057 } 058 } 059 060 /** 061 * If the resource exists and the checksum is correct, stream it to the client and return true. Otherwise, 062 * return false. 063 * 064 * @param resource 065 * to stream 066 * @return true if streamed, false otherwise 067 * @throws IOException 068 */ 069 public boolean stream(Resource resource) throws IOException 070 { 071 if (resource == null || !resource.exists()) 072 { 073 return false; 074 } 075 076 077 return streamer.streamResource(resource, checksum, ResourceStreamer.DEFAULT_OPTIONS); 078 } 079}