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Java > Open Source Codes > com > opensymphony > module > sitemesh > util > Container


1 /*
2  * Title: Container
3  * Description:
4  *
5  * This software is published under the terms of the OpenSymphony Software
6  * License version 1.1, of which a copy has been included with this
7  * distribution in the LICENSE.txt file.
8  */
9
10 package com.opensymphony.module.sitemesh.util;
11
12 import java.util.HashMap JavaDoc;
13 import java.util.Iterator JavaDoc;
14 import java.util.Map JavaDoc;
15
16 /**
17  * Utility for determining the Servlet Container the application is running in.
18  * Currently supported containers: Tomcat, Resin, Orion, OC4J, WebLogic, HPAS, JRun,
19  * Websphere.
20  *
21  * <h3>Usage:</h3>
22  *
23  * <code>if (Container.get() == Container.TOMCAT) { .... }</code>
24  *
25  * @author <a HREF="mailto:joe@truemesh.com">Joe Walnes</a>
26  * @version $Revision: 1.2 $
27  */
28 public final class Container {
29     public static final int UNKNOWN = 0;
30     public static final int TOMCAT = 1;
31     public static final int RESIN = 2;
32     public static final int ORION = 3; // Orion or OC4J
33 public static final int WEBLOGIC = 4;
34     public static final int HPAS = 5;
35     public static final int JRUN = 6;
36     public static final int WEBSPHERE = 7;
37
38     private static int result = -1;
39
40     /**
41      * A map containing classes that can be searched for,
42      * and which container they are typically found in.
43      */
44     private static Map JavaDoc classMappings = null;
45
46     static {
47         // initialize the classes that can be searched for
48 classMappings = new HashMap JavaDoc(6);
49         classMappings.put("org.apache.jasper.runtime.JspFactoryImpl", new Integer JavaDoc(TOMCAT));
50         classMappings.put("com.caucho.jsp.JspServlet", new Integer JavaDoc(RESIN));
51         classMappings.put("com.evermind.server.http.JSPServlet", new Integer JavaDoc(ORION));
52         classMappings.put("weblogic.servlet.JSPServlet", new Integer JavaDoc(WEBLOGIC));
53         classMappings.put("com.hp.mwlabs.j2ee.containers.servlet.jsp.JspServlet", new Integer JavaDoc(HPAS));
54         classMappings.put("jrun.servlet.WebApplicationService", new Integer JavaDoc(JRUN));
55         classMappings.put("com.ibm.ws.webcontainer.jsp.servlet.JspServlet", new Integer JavaDoc(WEBSPHERE));
56     }
57
58     /** Get the current container. */
59     public static int get() {
60         if (result == -1) {
61             final String JavaDoc classMatch = searchForClosestClass(classMappings);
62
63             if (classMatch == null) {
64                 result = UNKNOWN;
65             }
66             else {
67                 result = ((Integer JavaDoc) classMappings.get(classMatch)).intValue();
68             }
69         }
70         return result;
71     }
72
73     /**
74      * Walk up the classloader hierachy and attempt to find a class in the classMappings Map
75      * that can be loaded.
76      *
77      * @return Name of the match class, or null if not found.
78      */
79     private static String JavaDoc searchForClosestClass(Map JavaDoc classMappings) {
80         // get closest classloader
81 ClassLoader JavaDoc loader = Container.class.getClassLoader();
82
83         // iterate up through the classloader hierachy (through parents), until no more left.
84 while (loader != null) {
85
86             for (Iterator JavaDoc iterator = classMappings.keySet().iterator(); iterator.hasNext();) {
87                 String JavaDoc className = (String JavaDoc) iterator.next();
88
89                 try {
90                     // attempt to load current classname with current classloader
91 loader.loadClass(className);
92                     // if no exception has been thrown, we're in luck.
93 return className;
94                 }
95                 catch (ClassNotFoundException JavaDoc e) {
96                     // no problem... we'll keep trying...
97 }
98             }
99             loader = loader.getParent();
100         }
101
102         // couldn't find anything
103 return null;
104     }
105 }
106
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