src/be/nikiroo/utils/MarkableFileInputStream.java

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