001// ***************************************************************************************************************************
002// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
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006// *                                                                                                                         *
007// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
008// *                                                                                                                         *
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011// * specific language governing permissions and limitations under the License.                                              *
012// ***************************************************************************************************************************
013package org.apache.juneau.encoders;
014
015import java.io.*;
016
017/**
018 * Used for enabling decompression on requests and compression on responses, such as support for GZIP compression.
019 * 
020 * <h5 class='topic'>Description</h5>
021 * 
022 * Used to wrap input and output streams within compression/decompression streams.
023 * 
024 * <p>
025 * Encoders are registered with <code>RestServlets</code> through the <ja>@RestResource.encoders()</ja> annotation.
026 */
027public abstract class Encoder {
028
029   /**
030    * Converts the specified compressed input stream into an uncompressed stream.
031    * 
032    * @param is The compressed stream.
033    * @return The uncompressed stream.
034    * @throws IOException If any errors occur, such as on a stream that's not a valid GZIP input stream.
035    */
036   public abstract InputStream getInputStream(InputStream is) throws IOException;
037
038   /**
039    * Converts the specified uncompressed output stream into an uncompressed stream.
040    * 
041    * @param os The uncompressed stream.
042    * @return The compressed stream stream.
043    * @throws IOException If any errors occur.
044    */
045   public abstract OutputStream getOutputStream(OutputStream os) throws IOException;
046
047   /**
048    * Returns the codings in <code>Content-Encoding</code> and <code>Accept-Encoding</code> headers that this encoder
049    * handles (e.g. <js>"gzip"</js>).
050    * 
051    * @return The codings that this encoder handles.
052    */
053   public abstract String[] getCodings();
054}