如何从Hadoop序列文件中获取最后修改日期？

我正在使用一个将BinaryFiles(jpegs)转换为Hadoop序列文件(HSF)的映射器:

    public void map(Object key, Text value, Context context) 
throws IOException, InterruptedException {

    String uri = value.toString().replace(" ", "%20");
    Configuration conf = new Configuration();

    FSDataInputStream in = null;
    try {
        FileSystem fs = FileSystem.get(URI.create(uri), conf);
        in = fs.open(new Path(uri));
        java.io.ByteArrayOutputStream bout = new ByteArrayOutputStream();
        byte buffer[] = new byte[1024 * 1024];

        while( in.read(buffer, 0, buffer.length) >= 0 ) {
            bout.write(buffer);
        }
        context.write(value, new BytesWritable(bout.toByteArray()));

然后我有一个读取HSF的第二个映射器,因此:

public  class ImagePHashMapper extends Mapper{

    public void map(Text key, BytesWritable value, Context context) throws IOException,InterruptedException {
        //get the PHash for this specific file
        String PHashStr;
        try {
            PHashStr = calculatePhash(value.getBytes());

和calculatePhash是:

        static String calculatePhash(byte[] imageData) throws NoSuchAlgorithmException {
        //get the PHash for this specific data
        //PHash requires inputstream rather than byte array
        InputStream is = new ByteArrayInputStream(imageData);
        String ph;
        try {
            ImagePHash ih = new ImagePHash();
            ph = ih.getHash(is);
            System.out.println ("file: " + is.toString() + " phash: " +ph);
        } catch (Exception e) {
            e.printStackTrace();
            return "Internal error with ImagePHash.getHash";
        } 

        return ph;

这一切都运行正常,但我希望calculatePhash写出每个jpeg的最后修改日期.我知道我可以file.lastModified()用来获取文件中的最后一个修改日期但是有没有办法在map或calculatePhash中得到它？我是Java的菜鸟.TIA!