    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.tapestry5.internal.services.ResourceStreamer;
    018import org.apache.tapestry5.ioc.Resource;
    019
    020import java.io.IOException;
    021
    022/**
    023 * Utility used by {@link org.apache.tapestry5.services.assets.AssetRequestHandler} implementations
    024 * where the first folder in the extra path is actually a computed checksum of the resource's content.
    025 *
    026 * @since 5.4
    027 */
    028public class ChecksumPath
    029{
    030    public final String checksum;
    031
    032    public final String resourcePath;
    033
    034    private final ResourceStreamer streamer;
    035
    036    public ChecksumPath(ResourceStreamer streamer, String baseFolder, String extraPath)
    037    {
    038        this.streamer = streamer;
    039        int slashx = extraPath.indexOf('/');
    040
    041        checksum = extraPath.substring(0, slashx);
    042
    043        String morePath = extraPath.substring(slashx + 1);
    044
    045        resourcePath = baseFolder == null
    046                ? morePath
    047                : baseFolder + "/" + morePath;
    048    }
    049
    050    /**
    051     * If the resource exists and the checksum is correct, stream it to the client and return true. Otherwise,
    052     * return false.
    053     *
    054     * @param resource
    055     *         to stream
    056     * @return true if streamed, false otherwise
    057     * @throws IOException
    058     */
    059    public boolean stream(Resource resource) throws IOException
    060    {
    061        if (resource == null || !resource.exists())
    062        {
    063            return false;
    064        }
    065
    066
    067        return streamer.streamResource(resource, checksum, ResourceStreamer.DEFAULT_OPTIONS);
    068    }
    069}