| 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 | } |