annotate src/com/tmate/hgkit/ll/DigestHelper.java @ 28:b2251b7a9823

Explicit cons arg for clone is more error-prone
author Artem Tikhomirov <tikhomirov.artem@gmail.com>
date Tue, 11 Jan 2011 04:34:34 +0100
parents 571e1b2cc3f7
children 346b66add79d
rev   line source
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1 /**
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2 * Copyright (c) 2010 Artem Tikhomirov
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3 */
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4 package com.tmate.hgkit.ll;
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5
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6 import java.io.IOException;
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7 import java.io.InputStream;
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8 import java.security.MessageDigest;
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9 import java.security.NoSuchAlgorithmException;
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10
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11 /**
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12 *
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13 * @author artem
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14 */
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15 public class DigestHelper {
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16 private MessageDigest sha1;
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17
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18 public DigestHelper() {
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19 }
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20
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21 private MessageDigest getSHA1() {
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22 if (sha1 == null) {
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23 try {
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24 sha1 = MessageDigest.getInstance("SHA-1");
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25 } catch (NoSuchAlgorithmException ex) {
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26 // could hardly happen, JDK from Sun always has sha1.
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27 ex.printStackTrace(); // FIXME log error
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28 }
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29 }
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30 return sha1;
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31 }
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32
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33 // XXX perhaps, digest functions should throw an exception, as it's caller responsibility to deal with eof, etc
17
571e1b2cc3f7 Query file for its parents. Demo of recently added ignore and digest support from within cat cmd
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34 public String sha1(byte[] nodeidParent1, byte[] nodeidParent2, byte[] data) {
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35 MessageDigest alg = getSHA1();
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571e1b2cc3f7 Query file for its parents. Demo of recently added ignore and digest support from within cat cmd
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36 alg.update(nodeidParent1);
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37 alg.update(nodeidParent2);
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38 byte[] digest = alg.digest(data);
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39 assert digest.length == 20;
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40 return toHexString(digest, 0, 20);
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41 }
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42
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43 public byte[] sha1(InputStream is /*ByteBuffer*/) throws IOException {
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44 MessageDigest alg = getSHA1();
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45 byte[] buf = new byte[1024];
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46 int c;
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47 while ((c = is.read(buf)) != -1) {
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48 alg.update(buf, 0, c);
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49 }
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50 byte[] digest = alg.digest();
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51 return digest;
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52 }
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53
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54 public String toHexString(byte[] data, final int offset, final int count) {
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55 char[] result = new char[count << 1];
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56 final String hexDigits = "0123456789abcdef";
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57 final int end = offset+count;
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58 for (int i = offset, j = 0; i < end; i++) {
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59 result[j++] = hexDigits.charAt((data[i] >>> 4) & 0x0F);
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60 result[j++] = hexDigits.charAt(data[i] & 0x0F);
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61 }
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62 return new String(result);
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63 }
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64 }