001    /****************************************************************
002     * Licensed to the Apache Software Foundation (ASF) under one   *
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004     * distributed with this work for additional information        *
005     * regarding copyright ownership.  The ASF licenses this file   *
006     * to you under the Apache License, Version 2.0 (the            *
007     * "License"); you may not use this file except in compliance   *
008     * with the License.  You may obtain a copy of the License at   *
009     *                                                              *
010     *   http://www.apache.org/licenses/LICENSE-2.0                 *
011     *                                                              *
012     * Unless required by applicable law or agreed to in writing,   *
013     * software distributed under the License is distributed on an  *
014     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY       *
015     * KIND, either express or implied.  See the License for the    *
016     * specific language governing permissions and limitations      *
017     * under the License.                                           *
018     ****************************************************************/
019    
020    package org.apache.james.mime4j.storage;
021    
022    import java.io.IOException;
023    import java.io.InputStream;
024    
025    /**
026     * Can be used to read data that has been stored by a {@link StorageProvider}.
027     */
028    public interface Storage {
029        /**
030         * Returns an <code>InputStream</code> that can be used to read the stored
031         * data. The input stream should be closed by the caller when it is no
032         * longer needed.
033         * <p>
034         * Note: The stream should NOT be wrapped in a
035         * <code>BufferedInputStream</code> by the caller. If the implementing
036         * <code>Storage</code> creates a stream which would benefit from being
037         * buffered it is the <code>Storage</code>'s responsibility to wrap it.
038         *
039         * @return an <code>InputStream</code> for reading the stored data.
040         * @throws IOException
041         *             if an I/O error occurs.
042         * @throws IllegalStateException
043         *             if this <code>Storage</code> instance has been deleted.
044         */
045        InputStream getInputStream() throws IOException;
046    
047        /**
048         * Deletes the data held by this <code>Storage</code> as soon as possible.
049         * Deleting an already deleted <code>Storage</code> has no effect.
050         */
051        void delete();
052    
053    }