Java tutorial
/* * Copyright (C) 2008-2010, Google Inc. * Copyright (C) 2008-2009, Robin Rosenberg <robin.rosenberg@dewire.com> * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org> * and other copyright owners as documented in the project's IP log. * * This program and the accompanying materials are made available * under the terms of the Eclipse Distribution License v1.0 which * accompanies this distribution, is reproduced below, and is * available at http://www.eclipse.org/org/documents/edl-v10.php * * All rights reserved. * * Redistribution and use in source and binary forms, with or * without modification, are permitted provided that the following * conditions are met: * * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * - Redistributions in binary form must reproduce the above * copyright notice, this list of conditions and the following * disclaimer in the documentation and/or other materials provided * with the distribution. * * - Neither the name of the Eclipse Foundation, Inc. nor the * names of its contributors may be used to endorse or promote * products derived from this software without specific prior * written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ package org.eclipse.jgit.transport; import static java.nio.charset.StandardCharsets.UTF_8; import java.io.IOException; import java.io.OutputStream; import org.eclipse.jgit.lib.Constants; import org.eclipse.jgit.util.RawParseUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * Write Git style pkt-line formatting to an output stream. * <p> * This class is not thread safe and may issue multiple writes to the underlying * stream for each method call made. * <p> * This class performs no buffering on its own. This makes it suitable to * interleave writes performed by this class with writes performed directly * against the underlying OutputStream. */ public class PacketLineOut { private static final Logger log = LoggerFactory.getLogger(PacketLineOut.class); private final OutputStream out; private final byte[] lenbuffer; private boolean flushOnEnd; private boolean usingSideband; /** * Create a new packet line writer. * * @param outputStream * stream. */ public PacketLineOut(OutputStream outputStream) { out = outputStream; lenbuffer = new byte[5]; flushOnEnd = true; } /** * Set the flush behavior during {@link #end()}. * * @param flushOnEnd * if true, a flush-pkt written during {@link #end()} also * flushes the underlying stream. */ public void setFlushOnEnd(boolean flushOnEnd) { this.flushOnEnd = flushOnEnd; } /** * @return whether to add a sideband designator to each non-flush and * non-delim packet * @see #setUsingSideband * @since 5.5 */ public boolean isUsingSideband() { return usingSideband; } /** * @param value If true, when writing packet lines, add, as the first * byte, a sideband designator to each non-flush and non-delim * packet. See pack-protocol.txt and protocol-v2.txt from the Git * project for more information, specifically the "side-band" and * "sideband-all" sections. * @since 5.5 */ public void setUsingSideband(boolean value) { this.usingSideband = value; } /** * Write a UTF-8 encoded string as a single length-delimited packet. * * @param s * string to write. * @throws java.io.IOException * the packet could not be written, the stream is corrupted as * the packet may have been only partially written. */ public void writeString(String s) throws IOException { writePacket(Constants.encode(s)); } /** * Write a binary packet to the stream. * * @param packet * the packet to write; the length of the packet is equal to the * size of the byte array. * @throws java.io.IOException * the packet could not be written, the stream is corrupted as * the packet may have been only partially written. */ public void writePacket(byte[] packet) throws IOException { writePacket(packet, 0, packet.length); } /** * Write a binary packet to the stream. * * @param buf * the packet to write * @param pos * first index within {@code buf}. * @param len * number of bytes to write. * @throws java.io.IOException * the packet could not be written, the stream is corrupted as * the packet may have been only partially written. * @since 4.5 */ public void writePacket(byte[] buf, int pos, int len) throws IOException { if (usingSideband) { formatLength(len + 5); out.write(lenbuffer, 0, 4); out.write(1); } else { formatLength(len + 4); out.write(lenbuffer, 0, 4); } out.write(buf, pos, len); if (log.isDebugEnabled()) { String s = RawParseUtils.decode(UTF_8, buf, pos, len); log.debug("git> " + s); //$NON-NLS-1$ } } /** * Write a packet delim marker (0001). * * @throws java.io.IOException * the marker could not be written, the stream is corrupted * as the marker may have been only partially written. * @since 5.0 */ public void writeDelim() throws IOException { formatLength(1); out.write(lenbuffer, 0, 4); log.debug("git> 0001"); //$NON-NLS-1$ } /** * Write a packet end marker, sometimes referred to as a flush command. * <p> * Technically this is a magical packet type which can be detected * separately from an empty string or an empty packet. * <p> * Implicitly performs a flush on the underlying OutputStream to ensure the * peer will receive all data written thus far. * * @throws java.io.IOException * the end marker could not be written, the stream is corrupted * as the end marker may have been only partially written. */ public void end() throws IOException { formatLength(0); out.write(lenbuffer, 0, 4); log.debug("git> 0000"); //$NON-NLS-1$ if (flushOnEnd) flush(); } /** * Flush the underlying OutputStream. * <p> * Performs a flush on the underlying OutputStream to ensure the peer will * receive all data written thus far. * * @throws java.io.IOException * the underlying stream failed to flush. */ public void flush() throws IOException { out.flush(); } private static final byte[] hexchar = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' }; private void formatLength(int w) { formatLength(lenbuffer, w); } static void formatLength(byte[] lenbuffer, int w) { int o = 3; while (o >= 0 && w != 0) { lenbuffer[o--] = hexchar[w & 0xf]; w >>>= 4; } while (o >= 0) lenbuffer[o--] = '0'; } }