lineatatimereader.java

JAVA网络编程技术内幕一书的源代码

/*
 * Java Network Programming, Second Edition
 * Merlin Hughes, Michael Shoffner, Derek Hamner
 * Manning Publications Company; ISBN 188477749X
 *
 * http://nitric.com/jnp/
 *
 * Copyright (c) 1997-1999 Merlin Hughes, Michael Shoffner, Derek Hamner;
 * all rights reserved; see license.txt for details.
 */

import java.io.*;

public class LineAtATimeReader extends FilterReader {
  public LineAtATimeReader (Reader reader) {
    super (reader);
  }

  protected boolean eol, eof, skipLF;
  
  public int read () throws IOException {
    synchronized (lock) {
      if (eol || eof)
        return -1;
      int chr = in.read ();
      if (skipLF && (chr == '\n'))
        chr = in.read ();
      skipLF = (chr == '\r');
      if ((chr == '\n') || (chr == '\r')) {
        eol = true;
        return -1;
      } else {
        eof = (chr == -1);
        return chr;
      }
    }
  }

  public int read (char[] data, int offset, int length) throws IOException {
    if (length <= 0)
      return 0;
    int amount = 0;
    synchronized (lock) {
      int chr;
      while ((amount < length) && ((chr = read ()) != -1))
        data[offset + (amount ++)] = (char) chr;
    }
    return (amount > 0) ? amount : -1;
  }

  public long skip (long amount) throws IOException {
    long skip = 0;
    synchronized (lock) {
      while ((skip < amount) && (read () != -1))
        ++ skip;
    }
    return skip;
  }

  protected boolean oldEOF, oldEOL, oldSkipLF;

  public void mark (int readAheadLimit) throws IOException {
    synchronized (lock) {
      in.mark (readAheadLimit);
      oldEOF = eof; oldEOL= eol; oldSkipLF = skipLF;
    }
  }

  public void reset () throws IOException {
    synchronized (lock) {
      in.reset ();
      eof = oldEOF; eol = oldEOL; skipLF = oldSkipLF;
    }
  }

  public boolean nextLine () throws IOException {
    synchronized (lock) {
      while (read () != -1);
      eol = false;
      return !eof;
    }
  }
}