readerinputstream.java

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/*
 * 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 ReaderInputStream extends InputStream {
  protected Reader reader;
  protected ByteArrayOutputStream byteArrayOut;
  protected Writer writer;
  protected char[] chars;
  protected byte[] buffer;
  protected int index, length;
  
  public ReaderInputStream (Reader reader) {
    this.reader = reader;
    byteArrayOut = new ByteArrayOutputStream ();
    writer = new OutputStreamWriter (byteArrayOut);
    chars = new char[1024];
  }

  public ReaderInputStream (Reader reader, String encoding) throws UnsupportedEncodingException {
    this.reader = reader;
    byteArrayOut = new ByteArrayOutputStream ();
    writer = new OutputStreamWriter (byteArrayOut, encoding);
    chars = new char[1024];
  }

  public int read () throws IOException {
    if (index >= length)
      fillBuffer ();
    if (index >= length)
      return -1;
    return 0xff & buffer[index ++];
  }

  protected void fillBuffer () throws IOException {
    if (length < 0)
      return;
    int numChars = reader.read (chars);
    if (numChars < 0) {
      length = -1;
    } else {
      byteArrayOut.reset ();
      writer.write (chars, 0, numChars);
      writer.flush ();
      buffer = byteArrayOut.toByteArray ();
      length = buffer.length;
      index = 0;
    }
  }

  public int read (byte[] data, int off, int len) throws IOException {
    if (index >= length)
      fillBuffer ();
    if (index >= length)
      return -1;
    int amount = Math.min (len, length - index);
    System.arraycopy (buffer, index, data, off, amount);
    index += amount;
    return amount;
  }

  public int available () throws IOException {
    return (index < length) ? length - index :
      ((length >= 0) && reader.ready ()) ? 1 : 0;
  }

  public void close () throws IOException {
    reader.close ();
  }
}