1 | package org.apache.velocity.util.introspection; |
2 | |
3 | /* |
4 | * Copyright 2001,2004 The Apache Software Foundation. |
5 | * |
6 | * Licensed under the Apache License, Version 2.0 (the "License"); |
7 | * you may not use this file except in compliance with the License. |
8 | * You may obtain a copy of the License at |
9 | * |
10 | * http://www.apache.org/licenses/LICENSE-2.0 |
11 | * |
12 | * Unless required by applicable law or agreed to in writing, software |
13 | * distributed under the License is distributed on an "AS IS" BASIS, |
14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
15 | * See the License for the specific language governing permissions and |
16 | * limitations under the License. |
17 | */ |
18 | |
19 | import java.util.Map; |
20 | import java.util.Set; |
21 | import java.util.HashMap; |
22 | import java.util.HashSet; |
23 | |
24 | import java.lang.reflect.Method; |
25 | |
26 | import org.apache.velocity.runtime.RuntimeServices; |
27 | import org.apache.velocity.runtime.RuntimeLogger; |
28 | |
29 | /** |
30 | * This basic function of this class is to return a Method |
31 | * object for a particular class given the name of a method |
32 | * and the parameters to the method in the form of an Object[] |
33 | * |
34 | * The first time the Introspector sees a |
35 | * class it creates a class method map for the |
36 | * class in question. Basically the class method map |
37 | * is a Hastable where Method objects are keyed by a |
38 | * concatenation of the method name and the names of |
39 | * classes that make up the parameters. |
40 | * |
41 | * For example, a method with the following signature: |
42 | * |
43 | * public void method(String a, StringBuffer b) |
44 | * |
45 | * would be mapped by the key: |
46 | * |
47 | * "method" + "java.lang.String" + "java.lang.StringBuffer" |
48 | * |
49 | * This mapping is performed for all the methods in a class |
50 | * and stored for |
51 | * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a> |
52 | * @author <a href="mailto:bob@werken.com">Bob McWhirter</a> |
53 | * @author <a href="mailto:szegedia@freemail.hu">Attila Szegedi</a> |
54 | * @author <a href="mailto:paulo.gaspar@krankikom.de">Paulo Gaspar</a> |
55 | * @version $Id: Introspector.java,v 1.21.4.1 2004/03/03 23:23:08 geirm Exp $ |
56 | */ |
57 | public class Introspector extends IntrospectorBase |
58 | { |
59 | /** |
60 | * define a public string so that it can be looked for |
61 | * if interested |
62 | */ |
63 | |
64 | public final static String CACHEDUMP_MSG = |
65 | "Introspector : detected classloader change. Dumping cache."; |
66 | |
67 | /** |
68 | * our engine runtime services |
69 | */ |
70 | private RuntimeLogger rlog = null; |
71 | |
72 | /** |
73 | * Recieves our RuntimeServices object |
74 | */ |
75 | public Introspector(RuntimeLogger logger) |
76 | { |
77 | this.rlog = logger; |
78 | } |
79 | |
80 | /** |
81 | * Gets the method defined by <code>name</code> and |
82 | * <code>params</code> for the Class <code>c</code>. |
83 | * |
84 | * @param c Class in which the method search is taking place |
85 | * @param name Name of the method being searched for |
86 | * @param params An array of Objects (not Classes) that describe the |
87 | * the parameters |
88 | * |
89 | * @return The desired Method object. |
90 | */ |
91 | public Method getMethod(Class c, String name, Object[] params) |
92 | throws Exception |
93 | { |
94 | /* |
95 | * just delegate to the base class |
96 | */ |
97 | |
98 | try |
99 | { |
100 | return super.getMethod( c, name, params ); |
101 | } |
102 | catch( MethodMap.AmbiguousException ae ) |
103 | { |
104 | /* |
105 | * whoops. Ambiguous. Make a nice log message and return null... |
106 | */ |
107 | |
108 | String msg = "Introspection Error : Ambiguous method invocation " |
109 | + name + "( "; |
110 | |
111 | for (int i = 0; i < params.length; i++) |
112 | { |
113 | if ( i > 0) |
114 | msg = msg + ", "; |
115 | |
116 | msg = msg + params[i].getClass().getName(); |
117 | } |
118 | |
119 | msg = msg + ") for class " + c; |
120 | |
121 | rlog.error( msg ); |
122 | } |
123 | |
124 | return null; |
125 | } |
126 | |
127 | /** |
128 | * Clears the classmap and classname |
129 | * caches, and logs that we did so |
130 | */ |
131 | protected void clearCache() |
132 | { |
133 | super.clearCache(); |
134 | rlog.info( CACHEDUMP_MSG ); |
135 | } |
136 | } |