source: branches/libc-0.6/src/gcc/libjava/java/beans/Beans.java@ 2516

Last change on this file since 2516 was 2, checked in by bird, 23 years ago

Initial revision
  • Property cvs2svn:cvs-rev set to 1.1
  • Property svn:eol-style set to native
  • Property svn:executable set to *
File size: 6.4 KB
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1/* java.beans.Beans
2 Copyright (C) 1998, 1999 Free Software Foundation, Inc.
3
4This file is part of GNU Classpath.
5
6GNU Classpath is free software; you can redistribute it and/or modify
7it under the terms of the GNU General Public License as published by
8the Free Software Foundation; either version 2, or (at your option)
9any later version.
10
11GNU Classpath is distributed in the hope that it will be useful, but
12WITHOUT ANY WARRANTY; without even the implied warranty of
13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14General Public License for more details.
15
16You should have received a copy of the GNU General Public License
17along with GNU Classpath; see the file COPYING. If not, write to the
18Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
1902111-1307 USA.
20
21Linking this library statically or dynamically with other modules is
22making a combined work based on this library. Thus, the terms and
23conditions of the GNU General Public License cover the whole
24combination.
25
26As a special exception, the copyright holders of this library give you
27permission to link this library with independent modules to produce an
28executable, regardless of the license terms of these independent
29modules, and to copy and distribute the resulting executable under
30terms of your choice, provided that you also meet, for each linked
31independent module, the terms and conditions of the license of that
32module. An independent module is a module which is not derived from
33or based on this library. If you modify this library, you may extend
34this exception to your version of the library, but you are not
35obligated to do so. If you do not wish to do so, delete this
36exception statement from your version. */
37
38
39package java.beans;
40
41import java.io.*;
42import java.applet.*;
43import gnu.java.io.*;
44
45/**
46 * <code>Beans</code> provides some helper methods that allow the basic operations of Bean-ness.
47 *
48 * @author John Keiser
49 * @since JDK1.1
50 * @version 1.1.0, 29 Jul 1998
51 *
52 */
53public class Beans {
54 static boolean designTime = false;
55 static boolean guiAvailable = true;
56
57
58 /**
59 * Once again, we have a java.beans class with only
60 * static methods that can be instantiated. When
61 * will the madness end? :)
62 */
63 public Beans() {
64 }
65
66 /**
67 * Allows you to instantiate a Bean. This method takes
68 * a ClassLoader from which to read the Bean and the
69 * name of the Bean.<P>
70 *
71 * The Bean name should be a dotted name, like a class.
72 * It can represent several things. Beans will search
73 * for the Bean using the name like this:<P>
74 * <OL>
75 * <LI>Searches for a serialized instance of the Bean
76 * using getResource(), mangling the Bean name by
77 * replacing the dots with slashes and appending .ser
78 * (for example, gnu.beans.BlahDeBlah would cause
79 * Beans to search for gnu/beans/BlahDeBlah.ser using
80 * getResource()).</LI>
81 * <LI>Searches for the Bean class using the beanName,
82 * and then instantiates it with the no-arg constructor.
83 * At that point, if it is an Applet, it provides it
84 * with AppletContext and AppletStub, and then calls
85 * init().</LI>
86 * </OL>
87 * @param cl the ClassLoader to use, or <CODE>null</CODE>
88 * to use the default ClassLoader.
89 * @param beanName the name of the Bean.
90 * @return the Bean.
91 * @XXX
92 */
93 public static Object instantiate(ClassLoader cl, String beanName) throws IOException, ClassNotFoundException {
94 Object bean;
95
96 InputStream serStream;
97 if(cl == null) {
98 serStream = ClassLoader.getSystemResourceAsStream(beanName.replace('.','/')+".ser");
99 } else {
100 serStream = cl.getResourceAsStream(beanName.replace('.','/')+".ser");
101 }
102 if(serStream != null) {
103 if(cl == null) {
104 ObjectInputStream ois = new ObjectInputStream(serStream);
105 bean = ois.readObject();
106 } else {
107 ClassLoaderObjectInputStream ois = new ClassLoaderObjectInputStream(serStream, cl);
108 bean = ois.readObject();
109 }
110 } else if(cl == null) {
111 Class beanClass = Class.forName(beanName);
112 try {
113 bean = beanClass.newInstance();
114 } catch(IllegalAccessException E) {
115 bean = null;
116 } catch(InstantiationException E) {
117 bean = null;
118 }
119 } else {
120 Class beanClass = cl.loadClass(beanName);
121 try {
122 bean = beanClass.newInstance();
123 } catch(IllegalAccessException E) {
124 bean = null;
125 } catch(InstantiationException E) {
126 bean = null;
127 }
128 }
129
130 if(bean instanceof Applet) {
131 Applet a = (Applet)bean;
132 //a.setAppletContext(???);
133 //a.setStub(???);
134 if(serStream == null) {
135 a.init();
136 }
137 }
138
139 return bean;
140 }
141
142 /**
143 * Get the Bean as a different class type.
144 * This should be used instead of casting to get a new
145 * type view of a Bean, because in the future there may
146 * be new types of Bean, even Beans spanning multiple
147 * Objects.
148 * @param bean the Bean to cast.
149 * @param newClass the Class to cast it to.
150 * @return the Bean as a new view, or if the operation
151 * could not be performed, the Bean itself.
152 */
153 public static Object getInstanceOf(Object bean, Class newClass) {
154 return bean;
155 }
156
157 /**
158 * Determine whether the Bean can be cast to a different
159 * class type.
160 * This should be used instead of instanceof to determine
161 * a Bean's castability, because in the future there may
162 * be new types of Bean, even Beans spanning multiple
163 * Objects.
164 * @param bean the Bean to cast.
165 * @param newClass the Class to cast it to.
166 * @return whether the Bean can be cast to the class type
167 * in question.
168 */
169 public static boolean isInstanceOf(Object bean, Class newBeanClass) {
170 return newBeanClass.isInstance(bean);
171 }
172
173 /**
174 * Find out whether the GUI is available to use.
175 * Defaults to true.
176 * @return whether the GUI is available to use.
177 */
178 public static boolean isGuiAvailable() {
179 return guiAvailable;
180 }
181
182 /**
183 * Find out whether it is design time. Design time means
184 * we are in a RAD tool.
185 * Defaults to false.
186 * @return whether it is design time.
187 */
188 public static boolean isDesignTime() {
189 return designTime;
190 }
191
192 /**
193 * Set whether the GUI is available to use.
194 * @param guiAvailable whether the GUI is available to use.
195 */
196 public static void setGuiAvailable(boolean guiAvailable) throws SecurityException {
197 Beans.guiAvailable = guiAvailable;
198 }
199
200 /**
201 * Set whether it is design time. Design time means we
202 * are in a RAD tool.
203 * @param designTime whether it is design time.
204 */
205 public static void setDesignTime(boolean designTime) throws SecurityException {
206 Beans.designTime = designTime;
207 }
208}
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