buf
*/
protected int pos;
/**
* The currently marked position in the stream. This defaults to 0, so a
* reset operation on the stream resets it to read from array index 0 in
* the buffer - even if the stream was initially created with an offset
* greater than 0
*/
protected int markedPos;
/**
* This indicates the maximum number of chars that can be read from this
* stream. It is the array index of the position after the last valid
* char in the buffer buf
*/
protected int count;
/**
* Create a new CharArrayReader that will read chars from the passed
* in char array. This stream will read from the beginning to the end
* of the array. It is identical to calling an overloaded constructor
* as CharArrayReader(buf, 0, buf.length).
*
* Note that this array is not copied. If its contents are changed
* while this stream is being read, those changes will be reflected in the
* chars supplied to the reader. Please use caution in changing the
* contents of the buffer while this stream is open.
*
* @param buffer The char array buffer this stream will read from.
*/
public CharArrayReader(char[] buffer)
{
this(buffer, 0, buffer.length);
}
/**
* Create a new CharArrayReader that will read chars from the passed
* in char array. This stream will read from position
* offset in the array for a length of
* length chars past offset. If the
* stream is reset to a position before offset then
* more than length chars can be read from the stream.
* The length value should be viewed as the array index
* one greater than the last position in the buffer to read.
*
* Note that this array is not copied. If its contents are changed
* while this stream is being read, those changes will be reflected in the
* chars supplied to the reader. Please use caution in changing the
* contents of the buffer while this stream is open.
*
* @param buffer The char array buffer this stream will read from.
* @param offset The index into the buffer to start reading chars from
* @param length The number of chars to read from the buffer
*/
public CharArrayReader(char[] buffer, int offset, int length)
{
super();
if (offset < 0 || length < 0 || offset > buffer.length)
throw new IllegalArgumentException();
buf = buffer;
count = offset + length;
if (count > buf.length)
count = buf.length;
pos = offset;
markedPos = pos;
}
/**
* This method closes the stream.
*/
public void close()
{
synchronized (lock)
{
buf = null;
}
}
/**
* This method sets the mark position in this stream to the current
* position. Note that the readlimit parameter in this
* method does nothing as this stream is always capable of
* remembering all the chars int it.
*
* Note that in this class the mark position is set by default to
* position 0 in the stream. This is in constrast to some other
* stream types where there is no default mark position.
*
* @param readAheadLimit The number of chars this stream must
* remember. This parameter is ignored.
*
* @exception IOException If an error occurs
*/
public void mark(int readAheadLimit) throws IOException
{
synchronized (lock)
{
if (buf == null)
throw new IOException("Stream closed");
// readAheadLimit is ignored per Java Class Lib. book, p. 318.
markedPos = pos;
}
}
/**
* This method overrides the markSupported method in
* Reader in order to return true -
* indicating that this stream class supports mark/reset
* functionality.
*
* @return true to indicate that this class supports
* mark/reset.
*/
public boolean markSupported()
{
return true;
}
/**
* This method reads one char from the stream. The pos
* counter is advanced to the next char to be read. The char read
* is returned as an int in the range of 0-65535. If the stream
* position is already at the end of the buffer, no char is read and
* a -1 is returned in order to indicate the end of the stream.
*
* @return The char read, or -1 if end of stream
*/
public int read() throws IOException
{
synchronized (lock)
{
if (buf == null)
throw new IOException("Stream closed");
if (pos < 0)
throw new ArrayIndexOutOfBoundsException(pos);
if (pos < count)
return ((int) buf[pos++]) & 0xFFFF;
return -1;
}
}
/**
* This method reads chars from the stream and stores them into a
* caller supplied buffer. It starts storing the data at index
* offset into the buffer and attempts to read
* len chars. This method can return before reading
* the number of chars requested if the end of the stream is
* encountered first. The actual number of chars read is returned.
* If no chars can be read because the stream is already at the end
* of stream position, a -1 is returned.
*
* This method does not block.
*
* @param b The array into which the chars read should be stored.
* @param off The offset into the array to start storing chars
* @param len The requested number of chars to read
*
* @return The actual number of chars read, or -1 if end of stream.
*/
public int read(char[] b, int off, int len) throws IOException
{
synchronized (lock)
{
if (buf == null)
throw new IOException("Stream closed");
/* Don't need to check pos value, arraycopy will check it. */
if (off < 0 || len < 0 || off + len > b.length)
throw new IndexOutOfBoundsException();
if (pos >= count)
return -1;
int numChars = Math.min(count - pos, len);
System.arraycopy(buf, pos, b, off, numChars);
pos += numChars;
return numChars;
}
}
/**
* Return true if more characters are available to be read.
*
* @return true to indicate that this stream is ready
* to be read.
*
* @specnote The JDK 1.3 API docs are wrong here. This method will
* return false if there are no more characters available.
*/
public boolean ready() throws IOException
{
if (buf == null)
throw new IOException("Stream closed");
return (pos < count);
}
/**
* This method sets the read position in the stream to the mark
* point by setting the pos variable equal to the
* mark variable. Since a mark can be set anywhere in
* the array, the mark/reset methods int this class can be used to
* provide random search capabilities for this type of stream.
*/
public void reset() throws IOException
{
synchronized (lock)
{
if (buf == null)
throw new IOException("Stream closed");
pos = markedPos;
}
}
/**
* This method attempts to skip the requested number of chars in the
* input stream. It does this by advancing the pos value by the
* specified number of chars. It this would exceed the length of the
* buffer, then only enough chars are skipped to position the stream at
* the end of the buffer. The actual number of chars skipped is returned.
*
* @param n The requested number of chars to skip
*
* @return The actual number of chars skipped.
*/
public long skip(long n) throws IOException
{
synchronized (lock)
{
if (buf == null)
throw new IOException("Stream closed");
// Even though the var numChars is a long, in reality it can never
// be larger than an int since the result of subtracting 2 positive
// ints will always fit in an int. Since we have to return a long
// anyway, numChars might as well just be a long.
long numChars = Math.min((long) (count - pos), n < 0 ? 0L : n);
pos += numChars;
return numChars;
}
}
}