Subclasses that intend to support efficient single-character input
- * should override this method.
- *
- * @return The character read, as an integer in the range 0 to 65535
- * (0x00-0xffff), or -1 if the end of the stream has
- * been reached
- *
- * @exception IOException If an I/O error occurs
- */
- public int read() throws IOException {
- char cb[] = new char[1];
- if (read(cb, 0, 1) == -1)
- return -1;
- else
- return cb[0];
- }
-
- /**
- * Reads characters into an array. This method will block until some input
- * is available, an I/O error occurs, or the end of the stream is reached.
- *
- * @param cbuf Destination buffer
- *
- * @return The number of characters read, or -1
- * if the end of the stream
- * has been reached
- *
- * @exception IOException If an I/O error occurs
- */
- public int read(char cbuf[]) throws IOException {
- return read(cbuf, 0, cbuf.length);
- }
-
- /**
- * Reads characters into a portion of an array. This method will block
- * until some input is available, an I/O error occurs, or the end of the
- * stream is reached.
- *
- * @param cbuf Destination buffer
- * @param off Offset at which to start storing characters
- * @param len Maximum number of characters to read
- *
- * @return The number of characters read, or -1 if the end of the
- * stream has been reached
- *
- * @exception IOException If an I/O error occurs
- */
- abstract public int read(char cbuf[], int off, int len) throws IOException;
-
- /** Maximum skip-buffer size */
- private static final int maxSkipBufferSize = 8192;
-
- /** Skip buffer, null until allocated */
- private char skipBuffer[] = null;
-
- /**
- * Skips characters. This method will block until some characters are
- * available, an I/O error occurs, or the end of the stream is reached.
- *
- * @param n The number of characters to skip
- *
- * @return The number of characters actually skipped
- *
- * @exception IllegalArgumentException If n is negative.
- * @exception IOException If an I/O error occurs
- */
- public long skip(long n) throws IOException {
- if (n < 0L)
- throw new IllegalArgumentException("skip value is negative");
- int nn = (int) Math.min(n, maxSkipBufferSize);
- synchronized (lock) {
- if ((skipBuffer == null) || (skipBuffer.length < nn))
- skipBuffer = new char[nn];
- long r = n;
- while (r > 0) {
- int nc = read(skipBuffer, 0, (int)Math.min(r, nn));
- if (nc == -1)
- break;
- r -= nc;
- }
- return n - r;
- }
- }
-
- /**
- * Tells whether this stream is ready to be read.
- *
- * @return True if the next read() is guaranteed not to block for input,
- * false otherwise. Note that returning false does not guarantee that the
- * next read will block.
- *
- * @exception IOException If an I/O error occurs
- */
- public boolean ready() throws IOException {
- return false;
- }
-
- /**
- * Tells whether this stream supports the mark() operation. The default
- * implementation always returns false. Subclasses should override this
- * method.
- *
- * @return true if and only if this stream supports the mark operation.
- */
- public boolean markSupported() {
- return false;
- }
-
- /**
- * Marks the present position in the stream. Subsequent calls to reset()
- * will attempt to reposition the stream to this point. Not all
- * character-input streams support the mark() operation.
- *
- * @param readAheadLimit Limit on the number of characters that may be
- * read while still preserving the mark. After
- * reading this many characters, attempting to
- * reset the stream may fail.
- *
- * @exception IOException If the stream does not support mark(),
- * or if some other I/O error occurs
- */
- public void mark(int readAheadLimit) throws IOException {
- throw new IOException("mark() not supported");
- }
-
- /**
- * Resets the stream. If the stream has been marked, then attempt to
- * reposition it at the mark. If the stream has not been marked, then
- * attempt to reset it in some way appropriate to the particular stream,
- * for example by repositioning it to its starting point. Not all
- * character-input streams support the reset() operation, and some support
- * reset() without supporting mark().
- *
- * @exception IOException If the stream has not been marked,
- * or if the mark has been invalidated,
- * or if the stream does not support reset(),
- * or if some other I/O error occurs
- */
- public void reset() throws IOException {
- throw new IOException("reset() not supported");
- }
-
- /**
- * Closes the stream and releases any system resources associated with
- * it. Once the stream has been closed, further read(), ready(),
- * mark(), reset(), or skip() invocations will throw an IOException.
- * Closing a previously closed stream has no effect.
- *
- * @exception IOException If an I/O error occurs
- */
- abstract public void close() throws IOException;
-
-}