bufferedreader.java

This is a resource based on j2me embedded,if you dont understand,you can connection with me .

     * @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[], int off, int len) throws IOException {
        synchronized (lock) {
	    ensureOpen();
            if ((off < 0) || (off > cbuf.length) || (len < 0) ||
                ((off + len) > cbuf.length) || ((off + len) < 0)) {
                throw new IndexOutOfBoundsException();
            } else if (len == 0) {
                return 0;
            }

	    int n = read1(cbuf, off, len);
	    if (n <= 0) return n;
	    while ((n < len) && in.ready()) {
		int n1 = read1(cbuf, off + n, len - n);
		if (n1 <= 0) break;
		n += n1;
	    }
	    return n;
	}
    }

    /**
     * Read a line of text.  A line is considered to be terminated by any one
     * of a line feed ('\n'), a carriage return ('\r'), or a carriage return
     * followed immediately by a linefeed.
     *
     * @param      ignoreLF  If true, the next '\n' will be skipped
     *
     * @return     A String containing the contents of the line, not including
     *             any line-termination characters, or null if the end of the
     *             stream has been reached
     * 
     * @see        java.io.LineNumberReader#readLine()
     *
     * @exception  IOException  If an I/O error occurs
     */
    String readLine(boolean ignoreLF) throws IOException {
	StringBuffer s = null;
	int startChar;
	boolean omitLF = ignoreLF || skipLF;

        synchronized (lock) {
	    ensureOpen();

	bufferLoop:
	    for (;;) {

		if (nextChar >= nChars)
		    fill();
		if (nextChar >= nChars) { /* EOF */
		    if (s != null && s.length() > 0)
			return s.toString();
		    else
			return null;
		}
		boolean eol = false;
		char c = 0;
		int i;

                /* Skip a leftover '\n', if necessary */
		if (omitLF && (cb[nextChar] == '\n')) 
                    nextChar++;
		skipLF = false;
		omitLF = false;

	    charLoop:
		for (i = nextChar; i < nChars; i++) {
		    c = cb[i];
		    if ((c == '\n') || (c == '\r')) {
			eol = true;
			break charLoop;
		    }
		}

		startChar = nextChar;
		nextChar = i;

		if (eol) {
		    String str;
		    if (s == null) {
			str = new String(cb, startChar, i - startChar);
		    } else {
			s.append(cb, startChar, i - startChar);
			str = s.toString();
		    }
		    nextChar++;
		    if (c == '\r') {
			skipLF = true;
		    }
		    return str;
		}
		
		if (s == null) 
		    s = new StringBuffer(defaultExpectedLineLength);
		s.append(cb, startChar, i - startChar);
	    }
        }
    }

    /**
     * Read a line of text.  A line is considered to be terminated by any one
     * of a line feed ('\n'), a carriage return ('\r'), or a carriage return
     * followed immediately by a linefeed.
     *
     * @return     A String containing the contents of the line, not including
     *             any line-termination characters, or null if the end of the
     *             stream has been reached
     *
     * @exception  IOException  If an I/O error occurs
     */
    public String readLine() throws IOException {
        return readLine(false);
    }

    /**
     * Skip characters.
     *
     * @param  n  The number of characters to skip
     *
     * @return    The number of characters actually skipped
     *
     * @exception  IllegalArgumentException  If <code>n</code> 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");
	}
	synchronized (lock) {
	    ensureOpen();
	    long r = n;
	    while (r > 0) {
		if (nextChar >= nChars)
		    fill();
		if (nextChar >= nChars)	/* EOF */
		    break;
		if (skipLF) {
		    skipLF = false;
		    if (cb[nextChar] == '\n') {
			nextChar++;
		    }
		}
		long d = nChars - nextChar;
		if (r <= d) {
		    nextChar += r;
		    r = 0;
		    break;
		}
		else {
		    r -= d;
		    nextChar = nChars;
		}
	    }
	    return n - r;
	}
    }

    /**
     * Tell whether this stream is ready to be read.  A buffered character
     * stream is ready if the buffer is not empty, or if the underlying
     * character stream is ready.
     *
     * @exception  IOException  If an I/O error occurs
     */
    public boolean ready() throws IOException {
	synchronized (lock) {
	    ensureOpen();

	    /* 
	     * If newline needs to be skipped and the next char to be read
	     * is a newline character, then just skip it right away.
	     */
	    if (skipLF) {
		/* Note that in.ready() will return true if and only if the next 
		 * read on the stream will not block.
		 */
		if (nextChar >= nChars && in.ready()) {
		    fill();
		}
		if (nextChar < nChars) {
		    if (cb[nextChar] == '\n') 
			nextChar++;
		    skipLF = false;
		} 
	    }
	    return (nextChar < nChars) || in.ready();
	}
    }

    /**
     * Tell whether this stream supports the mark() operation, which it does.
     */
    public boolean markSupported() {
	return true;
    }

    /**
     * Mark the present position in the stream.  Subsequent calls to reset()
     * will attempt to reposition the stream to this point.
     *
     * @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.  A limit value larger
     *                         than the size of the input buffer will cause a
     *                         new buffer to be allocated whose size is no
     *                         smaller than limit.  Therefore large values
     *                         should be used with care.
     *
     * @exception  IllegalArgumentException  If readAheadLimit is < 0
     * @exception  IOException  If an I/O error occurs
     */
    public void mark(int readAheadLimit) throws IOException {
	if (readAheadLimit < 0) {
	    throw new IllegalArgumentException("Read-ahead limit < 0");
	}
	synchronized (lock) {
	    ensureOpen();
	    this.readAheadLimit = readAheadLimit;
	    markedChar = nextChar;
	    markedSkipLF = skipLF;
	}
    }

    /**
     * Reset the stream to the most recent mark.
     *
     * @exception  IOException  If the stream has never been marked,
     *                          or if the mark has been invalidated
     */
    public void reset() throws IOException {
	synchronized (lock) {
	    ensureOpen();
	    if (markedChar < 0)
		throw new IOException((markedChar == INVALIDATED)
				      ? "Mark invalid"
				      : "Stream not marked");
	    nextChar = markedChar;
	    skipLF = markedSkipLF;
	}
    }

    /**
     * Close the stream.
     *
     * @exception  IOException  If an I/O error occurs
     */
    public void close() throws IOException {
	synchronized (lock) {
	    if (in == null)
		return;
	    in.close();
	    in = null;
	    cb = null;
	}
    }

}