hadoop序列文件真的很奇怪。我将图像打包到序列文件中，无法恢复图像。我做一些简单的测试。我发现在使用序列文件前后字节的大小甚至不一样。

Configuration confHadoop = new Configuration();
        FileSystem fs = FileSystem.get(confHadoop);

        String fileName = args[0];
        Path file = new Path(fs.getUri().toString() + "/" + fileName);
        Path seqFile = new Path("/temp.seq");
        SequenceFile.Writer writer = null;
        FSDataInputStream in = null;
        try{
            writer = SequenceFile.createWriter(confHadoop,Writer.file(seqFile), Writer.keyClass(Text.class),
                    Writer.valueClass(BytesWritable.class));

            in = fs.open(file);
            byte buffer[] = IOUtils.toByteArray(in);

            System.out.println("original size ---->  " + String.valueOf(buffer.length));
            writer.append(new Text(fileName), new BytesWritable(buffer));
            System.out.println(calculateMd5(buffer));
            writer.close();

        }finally{
            IOUtils.closeQuietly(in);
        }

        SequenceFile.Reader reader = new SequenceFile.Reader(confHadoop, Reader.file(seqFile));

        Text key = new Text();
        BytesWritable val = new BytesWritable();

        while (reader.next(key, val)) {
            System.out.println("size get from sequence file --->" + String.valueOf(val.getLength()));
            String md5 = calculateMd5(val.getBytes());
            Path readSeq=new Path("/write back.png");  
            FSDataOutputStream out = null;
            out = fs.create(readSeq);
            out.write(val.getBytes());  //YES! GOT THE ORIGIANL IAMGE
            out.close();
            System.out.println(md5);
            .............
}

输出显示我得到了相同的字节数，在我将映像写回本地磁盘后，我确信我得到了原始映像。但为什么md5值不一样呢？
我在这里犯了什么错？

14/04/22 16:21:35 INFO compress.CodecPool: Got brand-new compressor [.deflate]
original size ---->  485709
c413e36fd864b27d4c8927956298edbb
14/04/22 16:21:35 INFO compress.CodecPool: Got brand-new decompressor [.deflate]
size get from sequence file --->485709
322cce20b732126bcb8876c4fcd925cb