ByteArrayInputStream contains
- * an internal buffer that contains bytes that
- * may be read from the stream. An internal
- * counter keeps track of the next byte to
- * be supplied by the read method.
- *
- * Closing a ByteArrayInputStream has no effect. The methods in
- * this class can be called after the stream has been closed without
- * generating an IOException.
- *
- * @author Arthur van Hoff
- * @see java.io.StringBufferInputStream
- * @since JDK1.0
- */
-public
-class ByteArrayInputStream extends InputStream {
-
- /**
- * An array of bytes that was provided
- * by the creator of the stream. Elements buf[0]
- * through buf[count-1] are the
- * only bytes that can ever be read from the
- * stream; element buf[pos] is
- * the next byte to be read.
- */
- protected byte buf[];
-
- /**
- * The index of the next character to read from the input stream buffer.
- * This value should always be nonnegative
- * and not larger than the value of count.
- * The next byte to be read from the input stream buffer
- * will be buf[pos].
- */
- protected int pos;
-
- /**
- * The currently marked position in the stream.
- * ByteArrayInputStream objects are marked at position zero by
- * default when constructed. They may be marked at another
- * position within the buffer by the mark() method.
- * The current buffer position is set to this point by the
- * reset() method.
- *
- * If no mark has been set, then the value of mark is the offset
- * passed to the constructor (or 0 if the offset was not supplied).
- *
- * @since JDK1.1
- */
- protected int mark = 0;
-
- /**
- * The index one greater than the last valid character in the input
- * stream buffer.
- * This value should always be nonnegative
- * and not larger than the length of buf.
- * It is one greater than the position of
- * the last byte within buf that
- * can ever be read from the input stream buffer.
- */
- protected int count;
-
- /**
- * Creates a ByteArrayInputStream
- * so that it uses buf as its
- * buffer array.
- * The buffer array is not copied.
- * The initial value of pos
- * is 0 and the initial value
- * of count is the length of
- * buf.
- *
- * @param buf the input buffer.
- */
- public ByteArrayInputStream(byte buf[]) {
- this.buf = buf;
- this.pos = 0;
- this.count = buf.length;
- }
-
- /**
- * Creates ByteArrayInputStream
- * that uses buf as its
- * buffer array. The initial value of pos
- * is offset and the initial value
- * of count is the minimum of offset+length
- * and buf.length.
- * The buffer array is not copied. The buffer's mark is
- * set to the specified offset.
- *
- * @param buf the input buffer.
- * @param offset the offset in the buffer of the first byte to read.
- * @param length the maximum number of bytes to read from the buffer.
- */
- public ByteArrayInputStream(byte buf[], int offset, int length) {
- this.buf = buf;
- this.pos = offset;
- this.count = Math.min(offset + length, buf.length);
- this.mark = offset;
- }
-
- /**
- * Reads the next byte of data from this input stream. The value
- * byte is returned as an int in the range
- * 0 to 255. If no byte is available
- * because the end of the stream has been reached, the value
- * -1 is returned.
- *
- * This read method
- * cannot block.
- *
- * @return the next byte of data, or -1 if the end of the
- * stream has been reached.
- */
- public synchronized int read() {
- return (pos < count) ? (buf[pos++] & 0xff) : -1;
- }
-
- /**
- * Reads up to len bytes of data into an array of bytes
- * from this input stream.
- * If pos equals count,
- * then -1 is returned to indicate
- * end of file. Otherwise, the number k
- * of bytes read is equal to the smaller of
- * len and count-pos.
- * If k is positive, then bytes
- * buf[pos] through buf[pos+k-1]
- * are copied into b[off] through
- * b[off+k-1] in the manner performed
- * by System.arraycopy. The
- * value k is added into pos
- * and k is returned.
- *
- * This read method cannot block.
- *
- * @param b the buffer into which the data is read.
- * @param off the start offset in the destination array b
- * @param len the maximum number of bytes read.
- * @return the total number of bytes read into the buffer, or
- * -1 if there is no more data because the end of
- * the stream has been reached.
- * @exception NullPointerException If b is null.
- * @exception IndexOutOfBoundsException If off is negative,
- * len is negative, or len is greater than
- * b.length - off
- */
- public synchronized int read(byte b[], int off, int len) {
- if (b == null) {
- throw new NullPointerException();
- } else if (off < 0 || len < 0 || len > b.length - off) {
- throw new IndexOutOfBoundsException();
- }
-
- if (pos >= count) {
- return -1;
- }
-
- int avail = count - pos;
- if (len > avail) {
- len = avail;
- }
- if (len <= 0) {
- return 0;
- }
- PushbackInputStream.arraycopy(buf, pos, b, off, len);
- pos += len;
- return len;
- }
-
- /**
- * Skips n bytes of input from this input stream. Fewer
- * bytes might be skipped if the end of the input stream is reached.
- * The actual number k
- * of bytes to be skipped is equal to the smaller
- * of n and count-pos.
- * The value k is added into pos
- * and k is returned.
- *
- * @param n the number of bytes to be skipped.
- * @return the actual number of bytes skipped.
- */
- public synchronized long skip(long n) {
- long k = count - pos;
- if (n < k) {
- k = n < 0 ? 0 : n;
- }
-
- pos += k;
- return k;
- }
-
- /**
- * Returns the number of remaining bytes that can be read (or skipped over)
- * from this input stream.
- *
- * The value returned is count - pos,
- * which is the number of bytes remaining to be read from the input buffer.
- *
- * @return the number of remaining bytes that can be read (or skipped
- * over) from this input stream without blocking.
- */
- public synchronized int available() {
- return count - pos;
- }
-
- /**
- * Tests if this InputStream supports mark/reset. The
- * markSupported method of ByteArrayInputStream
- * always returns true.
- *
- * @since JDK1.1
- */
- public boolean markSupported() {
- return true;
- }
-
- /**
- * Set the current marked position in the stream.
- * ByteArrayInputStream objects are marked at position zero by
- * default when constructed. They may be marked at another
- * position within the buffer by this method.
- *
- * If no mark has been set, then the value of the mark is the - * offset passed to the constructor (or 0 if the offset was not - * supplied). - * - *
Note: The readAheadLimit for this class
- * has no meaning.
- *
- * @since JDK1.1
- */
- public void mark(int readAheadLimit) {
- mark = pos;
- }
-
- /**
- * Resets the buffer to the marked position. The marked position
- * is 0 unless another position was marked or an offset was specified
- * in the constructor.
- */
- public synchronized void reset() {
- pos = mark;
- }
-
- /**
- * Closing a ByteArrayInputStream has no effect. The methods in
- * this class can be called after the stream has been closed without
- * generating an IOException.
- *
- */ - public void close() throws IOException { - } - -}