01: /*
02: * @(#)SingletonStore.java
03: *
04: * Copyright (C) 2002-2003 Matt Albrecht
05: * groboclown@users.sourceforge.net
06: * http://groboutils.sourceforge.net
07: *
08: * Permission is hereby granted, free of charge, to any person obtaining a
09: * copy of this software and associated documentation files (the "Software"),
10: * to deal in the Software without restriction, including without limitation
11: * the rights to use, copy, modify, merge, publish, distribute, sublicense,
12: * and/or sell copies of the Software, and to permit persons to whom the
13: * Software is furnished to do so, subject to the following conditions:
14: *
15: * The above copyright notice and this permission notice shall be included in
16: * all copies or substantial portions of the Software.
17: *
18: * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19: * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20: * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
21: * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22: * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
23: * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
24: * DEALINGS IN THE SOFTWARE.
25: */
26:
27: package net.sourceforge.groboutils.util.classes.v1;
28:
29: /**
30: * Aids pluggable factories and related classes by being a central repository
31: * for storing a singleton, and creating means to load and change the singleton.
32: *
33: * @author Matt Albrecht <a href="mailto:groboclown@users.sourceforge.net">groboclown@users.sourceforge.net</a>
34: * @version $Date: 2003/02/10 22:52:36 $
35: * @since March 30, 2002
36: */
37: public class SingletonStore extends AbstractSingleStore {
38: private Class defaultImplementation;
39: private String sysPropertyKey;
40:
41: /**
42: * Constructor specifying all the parameters for using a singleton in this
43: * framework.
44: *
45: * @param instanceOf singletons must be of this class.
46: * @param defaultImpl the class which will be used if no valid
47: * implementation class can be found.
48: * @param sysPropertyKey the system property key to reference for the name
49: * of the implementation class.
50: */
51: public SingletonStore(Class instanceOf, Class defaultImpl,
52: String sysPropertyKey) {
53: super (instanceOf);
54: this .defaultImplementation = defaultImpl;
55: this .sysPropertyKey = sysPropertyKey;
56: }
57:
58: /**
59: * Sets the inner singleton to the default, which pulls from the system
60: * property key.
61: */
62: public void setDefaultSingleton() {
63: setSingletonFromProperty(this .sysPropertyKey);
64: }
65:
66: /**
67: * Set the singleton to the class specified in the given system
68: * property; if the class is invalid, then the default singleton class will
69: * be used instead.
70: *
71: * @param key the System property to reference for the classname to
72: * instantiate. It is passed to <tt>ClassLoadHelper</tt>
73: * @exception IllegalArgumentException if <tt>key</tt> is <tt>null</tt>.
74: * @see ClassLoadHelper#createObjectFromProperty( String, Class, boolean )
75: */
76: public void setSingletonFromProperty(String key) {
77: setSingleton(createFromProperty(key, this.defaultImplementation));
78: }
79: }
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