Java tutorial
/* * Copyright (C) 2008, Robin Rosenberg <robin.rosenberg@dewire.com> * Copyright (C) 2006-2008, 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.lib; import java.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.io.Serializable; import org.eclipse.jgit.annotations.Nullable; import org.eclipse.jgit.errors.InvalidObjectIdException; import org.eclipse.jgit.util.NB; import org.eclipse.jgit.util.RawParseUtils; /** * A SHA-1 abstraction. */ public class ObjectId extends AnyObjectId implements Serializable { private static final long serialVersionUID = 1L; private static final ObjectId ZEROID; private static final String ZEROID_STR; static { ZEROID = new ObjectId(0, 0, 0, 0, 0); ZEROID_STR = ZEROID.name(); } /** * Get the special all-null ObjectId. * * @return the all-null ObjectId, often used to stand-in for no object. */ public static final ObjectId zeroId() { return ZEROID; } /** * Test a string of characters to verify it is a hex format. * <p> * If true the string can be parsed with {@link #fromString(String)}. * * @param id * the string to test. * @return true if the string can converted into an ObjectId. */ public static final boolean isId(@Nullable String id) { if (id == null) { return false; } if (id.length() != Constants.OBJECT_ID_STRING_LENGTH) return false; try { for (int i = 0; i < Constants.OBJECT_ID_STRING_LENGTH; i++) { RawParseUtils.parseHexInt4((byte) id.charAt(i)); } return true; } catch (ArrayIndexOutOfBoundsException e) { return false; } } /** * Convert an ObjectId into a hex string representation. * * @param i * the id to convert. May be null. * @return the hex string conversion of this id's content. */ public static final String toString(ObjectId i) { return i != null ? i.name() : ZEROID_STR; } /** * Compare two object identifier byte sequences for equality. * * @param firstBuffer * the first buffer to compare against. Must have at least 20 * bytes from position fi through the end of the buffer. * @param fi * first offset within firstBuffer to begin testing. * @param secondBuffer * the second buffer to compare against. Must have at least 20 * bytes from position si through the end of the buffer. * @param si * first offset within secondBuffer to begin testing. * @return true if the two identifiers are the same. */ public static boolean equals(final byte[] firstBuffer, final int fi, final byte[] secondBuffer, final int si) { return firstBuffer[fi] == secondBuffer[si] && firstBuffer[fi + 1] == secondBuffer[si + 1] && firstBuffer[fi + 2] == secondBuffer[si + 2] && firstBuffer[fi + 3] == secondBuffer[si + 3] && firstBuffer[fi + 4] == secondBuffer[si + 4] && firstBuffer[fi + 5] == secondBuffer[si + 5] && firstBuffer[fi + 6] == secondBuffer[si + 6] && firstBuffer[fi + 7] == secondBuffer[si + 7] && firstBuffer[fi + 8] == secondBuffer[si + 8] && firstBuffer[fi + 9] == secondBuffer[si + 9] && firstBuffer[fi + 10] == secondBuffer[si + 10] && firstBuffer[fi + 11] == secondBuffer[si + 11] && firstBuffer[fi + 12] == secondBuffer[si + 12] && firstBuffer[fi + 13] == secondBuffer[si + 13] && firstBuffer[fi + 14] == secondBuffer[si + 14] && firstBuffer[fi + 15] == secondBuffer[si + 15] && firstBuffer[fi + 16] == secondBuffer[si + 16] && firstBuffer[fi + 17] == secondBuffer[si + 17] && firstBuffer[fi + 18] == secondBuffer[si + 18] && firstBuffer[fi + 19] == secondBuffer[si + 19]; } /** * Convert an ObjectId from raw binary representation. * * @param bs * the raw byte buffer to read from. At least 20 bytes must be * available within this byte array. * @return the converted object id. */ public static final ObjectId fromRaw(byte[] bs) { return fromRaw(bs, 0); } /** * Convert an ObjectId from raw binary representation. * * @param bs * the raw byte buffer to read from. At least 20 bytes after p * must be available within this byte array. * @param p * position to read the first byte of data from. * @return the converted object id. */ public static final ObjectId fromRaw(byte[] bs, int p) { final int a = NB.decodeInt32(bs, p); final int b = NB.decodeInt32(bs, p + 4); final int c = NB.decodeInt32(bs, p + 8); final int d = NB.decodeInt32(bs, p + 12); final int e = NB.decodeInt32(bs, p + 16); return new ObjectId(a, b, c, d, e); } /** * Convert an ObjectId from raw binary representation. * * @param is * the raw integers buffer to read from. At least 5 integers must * be available within this int array. * @return the converted object id. */ public static final ObjectId fromRaw(int[] is) { return fromRaw(is, 0); } /** * Convert an ObjectId from raw binary representation. * * @param is * the raw integers buffer to read from. At least 5 integers * after p must be available within this int array. * @param p * position to read the first integer of data from. * @return the converted object id. */ public static final ObjectId fromRaw(int[] is, int p) { return new ObjectId(is[p], is[p + 1], is[p + 2], is[p + 3], is[p + 4]); } /** * Convert an ObjectId from hex characters (US-ASCII). * * @param buf * the US-ASCII buffer to read from. At least 40 bytes after * offset must be available within this byte array. * @param offset * position to read the first character from. * @return the converted object id. */ public static final ObjectId fromString(byte[] buf, int offset) { return fromHexString(buf, offset); } /** * Convert an ObjectId from hex characters. * * @param str * the string to read from. Must be 40 characters long. * @return the converted object id. */ public static ObjectId fromString(String str) { if (str.length() != Constants.OBJECT_ID_STRING_LENGTH) { throw new InvalidObjectIdException(str); } return fromHexString(Constants.encodeASCII(str), 0); } private static final ObjectId fromHexString(byte[] bs, int p) { try { final int a = RawParseUtils.parseHexInt32(bs, p); final int b = RawParseUtils.parseHexInt32(bs, p + 8); final int c = RawParseUtils.parseHexInt32(bs, p + 16); final int d = RawParseUtils.parseHexInt32(bs, p + 24); final int e = RawParseUtils.parseHexInt32(bs, p + 32); return new ObjectId(a, b, c, d, e); } catch (ArrayIndexOutOfBoundsException e1) { throw new InvalidObjectIdException(bs, p, Constants.OBJECT_ID_STRING_LENGTH); } } /** * Construct an ObjectId from 160 bits provided in 5 words. * * @param new_1 * an int * @param new_2 * an int * @param new_3 * an int * @param new_4 * an int * @param new_5 * an int * @since 4.7 */ public ObjectId(int new_1, int new_2, int new_3, int new_4, int new_5) { w1 = new_1; w2 = new_2; w3 = new_3; w4 = new_4; w5 = new_5; } /** * Initialize this instance by copying another existing ObjectId. * <p> * This constructor is mostly useful for subclasses who want to extend an * ObjectId with more properties, but initialize from an existing ObjectId * instance acquired by other means. * * @param src * another already parsed ObjectId to copy the value out of. */ protected ObjectId(AnyObjectId src) { w1 = src.w1; w2 = src.w2; w3 = src.w3; w4 = src.w4; w5 = src.w5; } /** {@inheritDoc} */ @Override public ObjectId toObjectId() { return this; } private void writeObject(ObjectOutputStream os) throws IOException { os.writeInt(w1); os.writeInt(w2); os.writeInt(w3); os.writeInt(w4); os.writeInt(w5); } private void readObject(ObjectInputStream ois) throws IOException { w1 = ois.readInt(); w2 = ois.readInt(); w3 = ois.readInt(); w4 = ois.readInt(); w5 = ois.readInt(); } }