KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > org > apache > turbine > services > uniqueid > TurbineUniqueIdService


1 package org.apache.turbine.services.uniqueid;
2
3 /*
4  * Copyright 2001-2004 The Apache Software Foundation.
5  *
6  * Licensed under the Apache License, Version 2.0 (the "License")
7  * you may not use this file except in compliance with the License.
8  * You may obtain a copy of the License at
9  *
10  * http://www.apache.org/licenses/LICENSE-2.0
11  *
12  * Unless required by applicable law or agreed to in writing, software
13  * distributed under the License is distributed on an "AS IS" BASIS,
14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15  * See the License for the specific language governing permissions and
16  * limitations under the License.
17  */
18
19 import java.security.MessageDigest JavaDoc;
20
21 import org.apache.commons.codec.base64.Base64;
22
23 import org.apache.commons.logging.Log;
24 import org.apache.commons.logging.LogFactory;
25
26 import org.apache.turbine.Turbine;
27 import org.apache.turbine.services.InitializationException;
28 import org.apache.turbine.services.TurbineBaseService;
29 import org.apache.turbine.util.GenerateUniqueId;
30 import org.apache.turbine.util.RunData;
31
32 /**
33  * <p> This is an implementation of {@link UniqueIdService}.
34  *
35  * @author <a HREF="mailto:Rafal.Krzewski@e-point.pl">Rafal Krzewski</a>
36  * @author <a HREF="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
37  * @version $Id: TurbineUniqueIdService.java,v 1.9.2.2 2004/05/20 03:06:48 seade Exp $
38  */
39 public class TurbineUniqueIdService
40         extends TurbineBaseService
41         implements UniqueIdService
42 {
43     /** Logging */
44     private static Log log = LogFactory.getLog(TurbineUniqueIdService.class);
45
46     /** The identifier of this instance of turbine. */
47     protected static String JavaDoc turbineId = "UNKNOWN";
48
49     protected static String JavaDoc turbineURL = "UNKNOWN";
50
51     protected static int counter;
52
53     /**
54      * @deprecated Use init() instead
55      */
56     public void init(RunData data)
57             throws InitializationException
58     {
59         init();
60     }
61
62     /**
63      * <p> Initializes the service upon first Turbine.doGet()
64      * invocation.
65      */
66     public void init()
67             throws InitializationException
68     {
69         try
70         {
71             // This might be a problem if the unique Id Service runs
72 // before Turbine got its first request. In this case,
73 // getDefaultServerData will return just a dummy value
74 // which is the same for all instances of Turbine.
75 //
76 // @todo This needs definitely further working.
77 String JavaDoc url = Turbine.getDefaultServerData().toString();
78             
79             MessageDigest JavaDoc md = MessageDigest.getInstance("MD5");
80             byte [] bytesId = md.digest(url.getBytes("UTF-8"));
81             turbineId = new String JavaDoc(Base64.encode(bytesId));
82             
83             log.info("This is Turbine instance running at: " + url);
84             log.info("The instance id is #" + turbineId);
85             setInit(true);
86         }
87         catch (Exception JavaDoc e)
88         {
89             throw new InitializationException(
90                     "Could not initialize TurbineUniqueId Service", e);
91         }
92     }
93
94     /**
95      * <p> Writes a message to the log upon system shutdown.
96      */
97     public void shutdown()
98     {
99         log.info("Turbine instance running at " + turbineURL + " shutting down.");
100     }
101
102     /**
103      * <p> Returns an identifier of this Turbine instance that is unique
104      * both on the server and worldwide. This identifier is computed
105      * as an MD5 sum of the URL (including schema, address, port if
106      * different that 80/443 respecively, context and servlet name).
107      * There is an overwhelming probalility that this id will be
108      * different that all other Turbine instances online.
109      *
110      * @return A String with the instance identifier.
111      */
112     public String JavaDoc getInstanceId()
113     {
114         return turbineId;
115     }
116
117     /**
118      * <p> Returns an identifier that is unique within this turbine
119      * instance, but does not have random-like apearance.
120      *
121      * @return A String with the non-random looking instance
122      * identifier.
123      */
124     public String JavaDoc getUniqueId()
125     {
126         int current;
127         synchronized (TurbineUniqueIdService.class)
128         {
129             current = counter++;
130         }
131         String JavaDoc id = Integer.toString(current);
132
133         // If you manage to get more than 100 million of ids, you'll
134 // start getting ids longer than 8 characters.
135 if (current < 100000000)
136         {
137             id = ("00000000" + id).substring(id.length());
138         }
139         return id;
140     }
141
142     /**
143      * <p> Returns a unique identifier that looks like random data.
144      *
145      * @return A String with the random looking instance identifier.
146      */
147     public String JavaDoc getPseudorandomId()
148     {
149         return GenerateUniqueId.getIdentifier();
150     }
151 }
152
Popular Tags