| Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
| GenerateUniqueId |
|
| 2.6666666666666665;2,667 |
| 1 | package org.apache.turbine.util; | |
| 2 | ||
| 3 | ||
| 4 | /* | |
| 5 | * Licensed to the Apache Software Foundation (ASF) under one | |
| 6 | * or more contributor license agreements. See the NOTICE file | |
| 7 | * distributed with this work for additional information | |
| 8 | * regarding copyright ownership. The ASF licenses this file | |
| 9 | * to you under the Apache License, Version 2.0 (the | |
| 10 | * "License"); you may not use this file except in compliance | |
| 11 | * with the License. You may obtain a copy of the License at | |
| 12 | * | |
| 13 | * http://www.apache.org/licenses/LICENSE-2.0 | |
| 14 | * | |
| 15 | * Unless required by applicable law or agreed to in writing, | |
| 16 | * software distributed under the License is distributed on an | |
| 17 | * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY | |
| 18 | * KIND, either express or implied. See the License for the | |
| 19 | * specific language governing permissions and limitations | |
| 20 | * under the License. | |
| 21 | */ | |
| 22 | ||
| 23 | ||
| 24 | import java.util.Random; | |
| 25 | ||
| 26 | /** | |
| 27 | * This class generates a unique 10+ character id. This is good for | |
| 28 | * authenticating users or tracking users around. | |
| 29 | * | |
| 30 | * <p>This code was borrowed from Apache | |
| 31 | * JServ.JServServletManager.java. It is what Apache JServ uses to | |
| 32 | * generate session ids for users. Unfortunately, it was not included | |
| 33 | * in Apache JServ as a class, so I had to create one here in order to | |
| 34 | * use it. | |
| 35 | * | |
| 36 | * @author <a href="mailto:jon@clearink.com">Jon S. Stevens</a> | |
| 37 | * @author <a href="mailto:neeme@one.lv">Neeme Praks</a> | |
| 38 | * @version $Id: GenerateUniqueId.java 615328 2008-01-25 20:25:05Z tv $ | |
| 39 | */ | |
| 40 | 0 | public class GenerateUniqueId |
| 41 | { | |
| 42 | /* | |
| 43 | * Create a suitable string for session identification. Use | |
| 44 | * synchronized count and time to ensure uniqueness. Use random | |
| 45 | * string to ensure the timestamp cannot be guessed by programmed | |
| 46 | * attack. | |
| 47 | * | |
| 48 | * Format of id is <6 chars random><3 chars time><1+ char count> | |
| 49 | */ | |
| 50 | 0 | static private int session_count = 0; |
| 51 | 0 | static private long lastTimeVal = 0; |
| 52 | 0 | static private Random randomSource = new java.util.Random(); |
| 53 | ||
| 54 | // MAX_RADIX is 36 | |
| 55 | ||
| 56 | /* | |
| 57 | * We want to have a random string with a length of 6 characters. | |
| 58 | * Since we encode it BASE 36, we've to modulo it with the | |
| 59 | * following value: | |
| 60 | */ | |
| 61 | public final static long maxRandomLen = 2176782336L; // 36 ** 6 | |
| 62 | ||
| 63 | /* | |
| 64 | * The session identifier must be unique within the typical | |
| 65 | * lifespan of a Session; the value can roll over after that. 3 | |
| 66 | * characters: (this means a roll over after over a day, which is | |
| 67 | * much larger than a typical lifespan) | |
| 68 | */ | |
| 69 | public final static long maxSessionLifespanTics = 46656; // 36 ** 3 | |
| 70 | ||
| 71 | /* | |
| 72 | * Millisecons between different tics. So this means that the | |
| 73 | * 3-character time string has a new value every 2 seconds: | |
| 74 | */ | |
| 75 | public final static long ticDifference = 2000; | |
| 76 | ||
| 77 | /** | |
| 78 | * Get the unique id. | |
| 79 | * | |
| 80 | * <p>NOTE: This must work together with | |
| 81 | * get_jserv_session_balance() in jserv_balance.c | |
| 82 | * | |
| 83 | * @return A String with the new unique id. | |
| 84 | */ | |
| 85 | static synchronized public String getIdentifier() | |
| 86 | { | |
| 87 | 0 | StringBuffer sessionId = new StringBuffer(); |
| 88 | ||
| 89 | // Random value. | |
| 90 | 0 | long n = randomSource.nextLong(); |
| 91 | 0 | if (n < 0) n = -n; |
| 92 | 0 | n %= maxRandomLen; |
| 93 | ||
| 94 | // Add maxLen to pad the leading characters with '0'; remove | |
| 95 | // first digit with substring. | |
| 96 | 0 | n += maxRandomLen; |
| 97 | 0 | sessionId.append(Long.toString(n, Character.MAX_RADIX) |
| 98 | .substring(1)); | |
| 99 | ||
| 100 | 0 | long timeVal = (System.currentTimeMillis() / ticDifference); |
| 101 | ||
| 102 | // Cut. | |
| 103 | 0 | timeVal %= maxSessionLifespanTics; |
| 104 | ||
| 105 | // Padding, see above. | |
| 106 | 0 | timeVal += maxSessionLifespanTics; |
| 107 | ||
| 108 | 0 | sessionId.append(Long.toString(timeVal, Character.MAX_RADIX) |
| 109 | .substring(1)); | |
| 110 | ||
| 111 | /* | |
| 112 | * Make the string unique: append the session count since last | |
| 113 | * time flip. | |
| 114 | */ | |
| 115 | ||
| 116 | // Count sessions only within tics. So the 'real' session | |
| 117 | // count isn't exposed to the public. | |
| 118 | 0 | if (lastTimeVal != timeVal) |
| 119 | { | |
| 120 | 0 | lastTimeVal = timeVal; |
| 121 | 0 | session_count = 0; |
| 122 | } | |
| 123 | 0 | sessionId.append(Long.toString(++session_count, |
| 124 | Character.MAX_RADIX)); | |
| 125 | ||
| 126 | 0 | return sessionId.toString(); |
| 127 | } | |
| 128 | ||
| 129 | /** | |
| 130 | * Get the unique id. | |
| 131 | * | |
| 132 | * @param jsIdent A String. | |
| 133 | * @return A String with the new unique id. | |
| 134 | */ | |
| 135 | synchronized public String getIdentifier(String jsIdent) | |
| 136 | { | |
| 137 | 0 | if (jsIdent != null && jsIdent.length() > 0) |
| 138 | { | |
| 139 | 0 | return getIdentifier() + "." + jsIdent; |
| 140 | } | |
| 141 | 0 | return getIdentifier(); |
| 142 | } | |
| 143 | ||
| 144 | /** | |
| 145 | * Simple test of the functionality. | |
| 146 | * | |
| 147 | * @param args A String[] with the command line arguments. | |
| 148 | */ | |
| 149 | public static void main(String[] args) | |
| 150 | { | |
| 151 | 0 | System.out.println(GenerateUniqueId.getIdentifier()); |
| 152 | 0 | System.out.println(GenerateUniqueId.getIdentifier()); |
| 153 | 0 | System.out.println(GenerateUniqueId.getIdentifier()); |
| 154 | 0 | System.out.println(GenerateUniqueId.getIdentifier()); |
| 155 | 0 | } |
| 156 | } |