src/be/nikiroo/utils/streams/MarkableFileInputStream.java

   1 package be.nikiroo.utils.streams;
   2
   3 import java.io.File;
   4 import java.io.FileInputStream;
   5 import java.io.FileNotFoundException;
   6 import java.io.FilterInputStream;
   7 import java.io.IOException;
   8 import java.nio.channels.FileChannel;
   9
  10 /**
  11  * This is a markable (and thus reset-able) stream that you can create from a
  12  * FileInputStream.
  13  *
  14  * @author niki
  15  */
  16 public class MarkableFileInputStream extends FilterInputStream {
  17         private FileChannel channel;
  18         private long mark = 0;
  19
  20         /**
  21          * Create a new {@link MarkableFileInputStream} from this file.
  22          *
  23          * @param file
  24          *            the {@link File} to wrap
  25          *
  26          * @throws FileNotFoundException
  27          *             if the {@link File} cannot be found
  28          */
  29         public MarkableFileInputStream(File file) throws FileNotFoundException {
  30                 this(new FileInputStream(file));
  31         }
  32
  33         /**
  34          * Create a new {@link MarkableFileInputStream} from this stream.
  35          *
  36          * @param in
  37          *            the original {@link FileInputStream} to wrap
  38          */
  39         public MarkableFileInputStream(FileInputStream in) {
  40                 super(in);
  41                 channel = in.getChannel();
  42         }
  43
  44         @Override
  45         public boolean markSupported() {
  46                 return true;
  47         }
  48
  49         @Override
  50         public synchronized void mark(int readlimit) {
  51                 try {
  52                         mark = channel.position();
  53                 } catch (IOException ex) {
  54                         ex.printStackTrace();
  55                         mark = -1;
  56                 }
  57         }
  58
  59         @Override
  60         public synchronized void reset() throws IOException {
  61                 if (mark < 0) {
  62                         throw new IOException("mark position not valid");
  63                 }
  64                 channel.position(mark);
  65         }
  66 }