    001    // Copyright 2011 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
    015    package org.apache.tapestry5.services.assets;
    016
    017    import org.apache.tapestry5.ioc.Resource;
    018
    019    import java.io.IOException;
    020    import java.io.InputStream;
    021    import java.io.OutputStream;
    022
    023    /**
    024     * An object, derived from a {@link Resource}, that can be streamed (ultimately, to a client web browser).
    025     *
    026     * @since 5.3
    027     */
    028    public interface StreamableResource
    029    {
    030        /**
    031         * Describes the underlying {@link Resource} (or resources} for this streamble resource; expressly used
    032         * as part of the object's {@code toString()}.
    033         */
    034        String getDescription();
    035
    036        /**
    037         * Indicates if the content is compressed, or compressable.
    038         */
    039        CompressionStatus getCompression();
    040
    041        /**
    042         * Returns the MIME content type, e.g., "image/jpeg".
    043         */
    044        String getContentType();
    045
    046        /**
    047         * The size, in bytes, of the underlying bytestream.
    048         */
    049        int getSize();
    050
    051        /**
    052         * Streams the resource's content to the provided stream. The caller is responsible for flushing or closing
    053         * the output stream.
    054         */
    055        void streamTo(OutputStream os) throws IOException;
    056
    057        /**
    058         * Opens the content of the resource as an input stream; the caller is responsible for closing the stream
    059         * after reading it.
    060         *
    061         * @return stream of the contents of the resource
    062         * @throws IOException
    063         */
    064        InputStream openStream() throws IOException;
    065
    066        /**
    067         * Returns the time the resource was last modified, with accuracy to one second (so as to match
    068         * the HTTP request/response date headers.
    069         */
    070        long getLastModified();
    071    }