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Java > Open Source Codes > com > vladium > util > IJREVersion


1 /* Copyright (C) 2003 Vladimir Roubtsov. All rights reserved.
2  *
3  * This program and the accompanying materials are made available under
4  * the terms of the Common Public License v1.0 which accompanies this distribution,
5  * and is available at http://www.eclipse.org/legal/cpl-v10.html
6  *
7  * $Id: IJREVersion.java,v 1.1.1.1.2.1 2004/07/10 03:34:52 vlad_r Exp $
8  */
9 package com.vladium.util;
10
11 // ----------------------------------------------------------------------------
12 /**
13  * A constant collection to detect the current JRE version. Note that this code
14  * is more sophisticated then a mere check of "java.version" or "java.class.version"
15  * and similar system properties because some JVMs allow overriding those
16  * by the user (e.g., from the command line). This implementation relies on
17  * the core classes only and tries to minimize the number of security-sensitive
18  * methods it uses.<P>
19  *
20  * This interface is supported in Java 1.1+ and should be compiled with class
21  * version stamp 45.3 (-target 1.1).
22  *
23  * @author Vlad Roubtsov, (C) 2003
24  */
25 public
26 interface IJREVersion
27 {
28     // public: ................................................................
29
30     /** 'true' iff the current runtime version is 1.2 or later */
31     boolean JRE_1_2_PLUS = _JREVersion._JRE_1_2_PLUS; // static final but not inlinable
32 /** 'true' iff the current runtime version is 1.3 or later */
33     boolean JRE_1_3_PLUS = _JREVersion._JRE_1_3_PLUS; // static final but not inlinable
34 /** 'true' iff the current runtime version is 1.4 or later */
35     boolean JRE_1_4_PLUS = _JREVersion._JRE_1_4_PLUS; // static final but not inlinable
36
37     // supporting Java 1.5 is trivial...
38
39     boolean JRE_SUN_SIGNAL_COMPATIBLE = _JREVersion._JRE_SUN_SIGNAL_COMPATIBLE;
40     
41     /*
42      * Use a dummy nested class to fake a static initializer for the outer
43      * interface (I want IJREVersion as an interface and not a class so that
44      * all JRE_XXX constants could be imported via "implements").
45      */
46     abstract class _JREVersion
47     {
48         static final boolean _JRE_1_2_PLUS; // set in <clinit>
49 static final boolean _JRE_1_3_PLUS; // set in <clinit>
50 static final boolean _JRE_1_4_PLUS; // set in <clinit>
51
52         static final boolean _JRE_SUN_SIGNAL_COMPATIBLE; // set in <clinit>
53
54         private _JREVersion () {} // prevent subclassing
55
56         static
57         {
58             _JRE_1_2_PLUS = ((SecurityManager JavaDoc.class.getModifiers () & 0x0400) == 0);
59
60             boolean temp = false;
61             if (_JRE_1_2_PLUS)
62             {
63                 try
64                 {
65                     StrictMath.abs (1.0);
66                     temp = true;
67                 }
68                 catch (Error JavaDoc ignore) {}
69             }
70             _JRE_1_3_PLUS = temp;
71             
72             if (temp)
73             {
74                 temp = false;
75                 try
76                 {
77                     " ".subSequence (0, 0);
78                     temp = true;
79                 }
80                 catch (NoSuchMethodError JavaDoc ignore) {}
81             }
82             _JRE_1_4_PLUS = temp;
83             
84             temp = false;
85             try
86             {
87                 Class.forName ("sun.misc.Signal");
88                 Class.forName ("sun.misc.SignalHandler");
89                 
90                 temp = true;
91             }
92             catch (Throwable JavaDoc ignore) {}
93             
94             _JRE_SUN_SIGNAL_COMPATIBLE = temp;
95         }
96
97     } // end of nested class
98
99 } // end of interface
100 // ----------------------------------------------------------------------------
101
102
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