Source code: gnu/java/beans/decoder/MethodFinder.java
1 /* gnu.java.beans.decoder.MethodFinder
2 Copyright (C) 2004 Free Software Foundation, Inc.
3
4 This file is part of GNU Classpath.
5
6 GNU Classpath is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
9 any later version.
10
11 GNU Classpath is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with GNU Classpath; see the file COPYING. If not, write to the
18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
19 02110-1301 USA.
20
21 Linking this library statically or dynamically with other modules is
22 making a combined work based on this library. Thus, the terms and
23 conditions of the GNU General Public License cover the whole
24 combination.
25
26 As a special exception, the copyright holders of this library give you
27 permission to link this library with independent modules to produce an
28 executable, regardless of the license terms of these independent
29 modules, and to copy and distribute the resulting executable under
30 terms of your choice, provided that you also meet, for each linked
31 independent module, the terms and conditions of the license of that
32 module. An independent module is a module which is not derived from
33 or based on this library. If you modify this library, you may extend
34 this exception to your version of the library, but you are not
35 obligated to do so. If you do not wish to do so, delete this
36 exception statement from your version. */
37
38 package gnu.java.beans.decoder;
39
40 import java.lang.reflect.Constructor;
41 import java.lang.reflect.Method;
42 import java.util.HashMap;
43
44 class MethodFinder
45 {
46 /** Provides a mapping between a wrapper class and its corresponding primitive's type. */
47 private static HashMap typeMapping = new HashMap();
48
49 static {
50 typeMapping.put(Byte.class, Byte.TYPE);
51 typeMapping.put(Short.class, Short.TYPE);
52 typeMapping.put(Integer.class, Integer.TYPE);
53 typeMapping.put(Long.class, Long.TYPE);
54 typeMapping.put(Float.class, Float.TYPE);
55 typeMapping.put(Double.class, Double.TYPE);
56
57 typeMapping.put(Character.class, Character.TYPE);
58 typeMapping.put(Boolean.class, Boolean.TYPE);
59 }
60
61 private MethodFinder()
62 {
63 }
64
65 /** Searches a Method which can accept the given arguments.
66 *
67 * @param klass
68 * @param name
69 * @param arguments
70 * @return
71 * @throws NoSuchMethodException
72 */
73 static Method getMethod(Class klass, String name, Object[] arguments)
74 throws NoSuchMethodException
75 {
76 // prepares array containing the types of the arguments
77 Class[] argumentTypes = getArgumentTypes(arguments);
78
79 Method[] methods = klass.getMethods();
80
81 // iterates over all public methods
82 for (int i = 0; i < methods.length; i++)
83 {
84 if (methods[i].getName().equals(name))
85 {
86 if (matchingArgumentTypes(methods[i].getParameterTypes(),
87 argumentTypes))
88 return methods[i];
89 }
90 }
91
92 throw new NoSuchMethodException(
93 "Could not find a matching method named "
94 + name
95 + "() in class "
96 + klass);
97 }
98
99 static Constructor getConstructor(Class klass, Object[] arguments)
100 throws NoSuchMethodException
101 {
102 Class[] argumentTypes = getArgumentTypes(arguments);
103 Constructor[] constructors = klass.getConstructors();
104
105 // iterates over all public methods
106 for (int i = 0; i < constructors.length; i++)
107 {
108 if (matchingArgumentTypes(constructors[i].getParameterTypes(),
109 argumentTypes))
110 return constructors[i];
111 }
112
113 throw new NoSuchMethodException(
114 "Could not find a matching constructor in class " + klass);
115 }
116
117 /** Transforms an array of argument objects into an array of argument types.
118 * For each argument being null the argument is null, too. An argument type
119 * being null means: Accepts everything (although this can be ambigous).
120 *
121 * @param arguments
122 * @return
123 */
124 private static Class[] getArgumentTypes(Object[] arguments)
125 {
126 if (arguments == null)
127 return new Class[0];
128
129 // prepares array containing the types of the arguments
130 Class[] argumentTypes = new Class[arguments.length];
131 for (int i = 0; i < arguments.length; i++)
132 argumentTypes[i] =
133 (arguments[i] == null) ? null : arguments[i].getClass();
134 return argumentTypes;
135 }
136
137 /** Tests whether the argument types supplied to the method argument types
138 * are assignable. In addition to the assignment specifications this method
139 * handles the primitive's wrapper classes as if they were of their
140 * primitive type (e.g Boolean.class equals Boolean.TYPE).
141 * When a supplied argument type is null it is assumed that no argument
142 * object was supplied for it and the test for this particular parameter will
143 * pass.
144 *
145 * @param methodArgTypes
146 * @param suppliedArgTypes
147 * @return
148 */
149 private static boolean matchingArgumentTypes(
150 Class[] methodArgTypes,
151 Class[] suppliedArgTypes)
152 {
153 if (methodArgTypes.length != suppliedArgTypes.length)
154 return false;
155
156 for (int i = 0; i < methodArgTypes.length; i++)
157 {
158 if (suppliedArgTypes[i] == null)
159 {
160 // by definition a non-existant argument type (null) can be converted to everything
161 continue;
162 }
163 else if (typeMapping.containsKey(suppliedArgTypes[i]))
164 {
165 Class primitiveType =
166 (Class) typeMapping.get(suppliedArgTypes[i]);
167 if (!(methodArgTypes[i].isAssignableFrom(suppliedArgTypes[i])
168 || methodArgTypes[i].isAssignableFrom(primitiveType)))
169 return false;
170 }
171 else if (!methodArgTypes[i].isAssignableFrom(suppliedArgTypes[i]))
172 return false;
173 }
174
175 return true;
176 }
177 }