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 1709648 2015-10-20 17:08:10Z 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 | StringBuilder sessionId = new StringBuilder(); |
88 | ||
89 | // Random value. | |
90 | 0 | long n = randomSource.nextLong(); |
91 | 0 | if (n < 0) |
92 | { | |
93 | 0 | n = -n; |
94 | } | |
95 | 0 | n %= maxRandomLen; |
96 | ||
97 | // Add maxLen to pad the leading characters with '0'; remove | |
98 | // first digit with substring. | |
99 | 0 | n += maxRandomLen; |
100 | 0 | sessionId.append(Long.toString(n, Character.MAX_RADIX) |
101 | .substring(1)); | |
102 | ||
103 | 0 | long timeVal = (System.currentTimeMillis() / ticDifference); |
104 | ||
105 | // Cut. | |
106 | 0 | timeVal %= maxSessionLifespanTics; |
107 | ||
108 | // Padding, see above. | |
109 | 0 | timeVal += maxSessionLifespanTics; |
110 | ||
111 | 0 | sessionId.append(Long.toString(timeVal, Character.MAX_RADIX) |
112 | .substring(1)); | |
113 | ||
114 | /* | |
115 | * Make the string unique: append the session count since last | |
116 | * time flip. | |
117 | */ | |
118 | ||
119 | // Count sessions only within tics. So the 'real' session | |
120 | // count isn't exposed to the public. | |
121 | 0 | if (lastTimeVal != timeVal) |
122 | { | |
123 | 0 | lastTimeVal = timeVal; |
124 | 0 | session_count = 0; |
125 | } | |
126 | 0 | sessionId.append(Long.toString(++session_count, |
127 | Character.MAX_RADIX)); | |
128 | ||
129 | 0 | return sessionId.toString(); |
130 | } | |
131 | ||
132 | /** | |
133 | * Get the unique id. | |
134 | * | |
135 | * @param jsIdent A String. | |
136 | * @return A String with the new unique id. | |
137 | */ | |
138 | synchronized public String getIdentifier(String jsIdent) | |
139 | { | |
140 | 0 | if (jsIdent != null && jsIdent.length() > 0) |
141 | { | |
142 | 0 | return getIdentifier() + "." + jsIdent; |
143 | } | |
144 | 0 | return getIdentifier(); |
145 | } | |
146 | ||
147 | /** | |
148 | * Simple test of the functionality. | |
149 | * | |
150 | * @param args A String[] with the command line arguments. | |
151 | */ | |
152 | public static void main(String[] args) | |
153 | { | |
154 | 0 | System.out.println(GenerateUniqueId.getIdentifier()); |
155 | 0 | System.out.println(GenerateUniqueId.getIdentifier()); |
156 | 0 | System.out.println(GenerateUniqueId.getIdentifier()); |
157 | 0 | System.out.println(GenerateUniqueId.getIdentifier()); |
158 | 0 | } |
159 | } |