InputStream's in
- * order to form a single logical stream that can be read by applications
- * that expect only one stream.
- * - * The streams passed to the constructor method are read in order until - * they return -1 to indicate they are at end of stream. When a stream - * reports end of stream, it is closed, then the next stream is read. - * When the last stream is closed, the next attempt to read from this - * stream will return a -1 to indicate it is at end of stream. - *
- * If this stream is closed prior to all subordinate streams being read
- * to completion, all subordinate streams are closed.
- *
- * @author Aaron M. Renn (arenn@urbanophile.com)
- * @author Warren Levy
- * This method will block until the byte can be read.
- *
- * @return The byte read, or -1 if end of stream
- *
- * @exception IOException If an error occurs
- */
- public int read() throws IOException
- {
- int ch = -1;
-
- while (in != null && (ch = in.read()) < 0)
- {
- in.close();
- in = getNextStream();
- }
-
- return ch;
- }
-
- /**
- * This method reads bytes from a stream and stores them into a caller
- * supplied buffer. It starts storing the data at index
- * This method will block until at least one byte can be read.
- *
- * @param b The array into which bytes read should be stored
- * @param off The offset into the array to start storing bytes
- * @param len The requested number of bytes to read
- *
- * @return The actual number of bytes read, or -1 if end of stream
- *
- * @exception IOException If an error occurs
- */
- public int read(byte[] b, int off, int len) throws IOException
- {
- int ch = -1;
-
- // The validity of the parameters will be checked by in.read so
- // don't bother doing it here.
- while (in != null && (ch = in.read(b, off, len)) < 0)
- {
- in.close();
- in = getNextStream();
- }
-
- return ch;
- }
-
- /**
- * This private method is used to get the next SequenceInputStream that obtains
- * its list of subordinate InputStreams from the specified
- * Enumeration
- *
- * @param e An Enumeration that will return a list of
- * InputStreams to read in sequence
- */
- public SequenceInputStream(Enumeration e)
- {
- enum = e;
- in = (InputStream) enum.nextElement();
- in2 = null;
- }
-
- /**
- * This method creates a new SequenceInputStream that will read
- * the two specified subordinate InputStreams in sequence.
- *
- * @param s1 The first InputStream to read
- * @param s2 The second InputStream to read
- */
- public SequenceInputStream(InputStream s1, InputStream s2)
- {
- in = s1;
- in2 = s2;
- }
-
- /**
- * This method returns the number of bytes than can be read from the
- * currently being read subordinate stream before that stream could
- * block. Note that it is possible more bytes than this can actually
- * be read without the stream blocking. If a 0 is returned, then the
- * stream could block on the very next read.
- *
- * @return The number of bytes that can be read before blocking could occur
- *
- * @exception IOException If an error occurs
- */
- public int available() throws IOException
- {
- if (in == null)
- return 0;
-
- return in.available();
- }
-
- /**
- * Closes this stream. This will cause any remaining unclosed subordinate
- * InputStream's to be closed as well. Subsequent attempts to
- * read from this stream may cause an exception.
- *
- * @exception IOException If an error occurs
- */
- public void close() throws IOException
- {
- while (in != null)
- {
- in.close();
- in = getNextStream ();
- }
- }
-
- /**
- * This method reads an unsigned byte from the input stream and returns it
- * as an int in the range of 0-255. This method also will return -1 if
- * the end of the stream has been reached. This will only happen when
- * all of the subordinate streams have been read.
- * offset
- * into the buffer and attempts to read len bytes. This method
- * can return before reading the number of bytes requested. The actual number
- * of bytes read is returned as an int. A -1 is returend to indicate the
- * end of the stream. This will only happen when all of the subordinate
- * streams have been read.
- * InputStream to
- * read from. Returns null when no more streams are available.
- */
- private InputStream getNextStream()
- {
- InputStream nextIn = null;
-
- if (enum != null)
- {
- if (enum.hasMoreElements())
- nextIn = (InputStream) enum.nextElement();
- }
- else
- if (in2 != null)
- {
- nextIn = in2;
- in2 = null;
- }
-
- return nextIn;
- }
-}