001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.juneau.encoders;
018
019import java.io.*;
020
021/**
022 * Used for enabling decompression on requests and compression on responses, such as support for GZIP compression.
023 *
024 * <h5 class='topic'>Description</h5>
025 *
026 * Used to wrap input and output streams within compression/decompression streams.
027 *
028 * <p>
029 * Encoders are registered with <c>RestServlets</c> through the <ja>@Rest(encoders)</ja> annotation.
030 *
031 * <h5 class='section'>Notes:</h5><ul>
032 *    <li class='note'>This class is thread safe and reusable.
033 * </ul>
034 *
035 * <h5 class='section'>See Also:</h5><ul>
036 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/RestServerEncoders">Encoders</a>
037
038 * </ul>
039 */
040public abstract class Encoder {
041
042   /**
043    * Converts the specified compressed input stream into an uncompressed stream.
044    *
045    * @param is The compressed stream.
046    * @return The uncompressed stream.
047    * @throws IOException If any errors occur, such as on a stream that's not a valid GZIP input stream.
048    */
049   public abstract InputStream getInputStream(InputStream is) throws IOException;
050
051   /**
052    * Converts the specified uncompressed output stream into an uncompressed stream.
053    *
054    * @param os The uncompressed stream.
055    * @return The compressed stream stream.
056    * @throws IOException If any errors occur.
057    */
058   public abstract OutputStream getOutputStream(OutputStream os) throws IOException;
059
060   /**
061    * Returns the codings in <c>Content-Encoding</c> and <c>Accept-Encoding</c> headers that this encoder
062    * handles (e.g. <js>"gzip"</js>).
063    *
064    * @return The codings that this encoder handles.
065    */
066   public abstract String[] getCodings();
067}