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      1 /*
      2  * Copyright 2009 Mike Cumings
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *   http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.kenai.jbosh;
     18 
     19 import java.io.ByteArrayInputStream;
     20 import java.io.ByteArrayOutputStream;
     21 import java.io.IOException;
     22 import java.util.zip.GZIPInputStream;
     23 import java.util.zip.GZIPOutputStream;
     24 
     25 /**
     26  * Codec methods for compressing and uncompressing using GZIP.
     27  */
     28 final class GZIPCodec {
     29 
     30     /**
     31      * Size of the internal buffer when decoding.
     32      */
     33     private static final int BUFFER_SIZE = 512;
     34 
     35     ///////////////////////////////////////////////////////////////////////////
     36     // Constructors:
     37 
     38     /**
     39      * Prevent construction.
     40      */
     41     private GZIPCodec() {
     42         // Empty
     43     }
     44 
     45     /**
     46      * Returns the name of the codec.
     47      *
     48      * @return string name of the codec (i.e., "gzip")
     49      */
     50     public static String getID() {
     51         return "gzip";
     52     }
     53 
     54     /**
     55      * Compress/encode the data provided using the GZIP format.
     56      *
     57      * @param data data to compress
     58      * @return compressed data
     59      * @throws IOException on compression failure
     60      */
     61     public static byte[] encode(final byte[] data) throws IOException {
     62         ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
     63         GZIPOutputStream gzOut = null;
     64         try {
     65             gzOut = new GZIPOutputStream(byteOut);
     66             gzOut.write(data);
     67             gzOut.close();
     68             byteOut.close();
     69             return byteOut.toByteArray();
     70         } finally {
     71             gzOut.close();
     72             byteOut.close();
     73         }
     74     }
     75 
     76     /**
     77      * Uncompress/decode the data provided using the GZIP format.
     78      *
     79      * @param data data to uncompress
     80      * @return uncompressed data
     81      * @throws IOException on decompression failure
     82      */
     83     public static byte[] decode(final byte[] compressed) throws IOException {
     84         ByteArrayInputStream byteIn = new ByteArrayInputStream(compressed);
     85         ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
     86         GZIPInputStream gzIn = null;
     87         try {
     88             gzIn = new GZIPInputStream(byteIn);
     89             int read;
     90             byte[] buffer = new byte[BUFFER_SIZE];
     91             do {
     92                 read = gzIn.read(buffer);
     93                 if (read > 0) {
     94                     byteOut.write(buffer, 0, read);
     95                 }
     96             } while (read >= 0);
     97             return byteOut.toByteArray();
     98         } finally {
     99             gzIn.close();
    100             byteOut.close();
    101         }
    102     }
    103 
    104 }
    105