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17 package org.apache.commons.jexl.util.introspection;
18
19 import java.lang.reflect.Method;
20
21 import org.apache.commons.logging.Log;
22
23
24 /***
25 * This basic function of this class is to return a Method
26 * object for a particular class given the name of a method
27 * and the parameters to the method in the form of an Object[]
28 *
29 * The first time the Introspector sees a
30 * class it creates a class method map for the
31 * class in question. Basically the class method map
32 * is a Hastable where Method objects are keyed by a
33 * concatenation of the method name and the names of
34 * classes that make up the parameters.
35 *
36 * For example, a method with the following signature:
37 *
38 * public void method(String a, StringBuffer b)
39 *
40 * would be mapped by the key:
41 *
42 * "method" + "java.lang.String" + "java.lang.StringBuffer"
43 *
44 * This mapping is performed for all the methods in a class
45 * and stored for
46 * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
47 * @author <a href="mailto:bob@werken.com">Bob McWhirter</a>
48 * @author <a href="mailto:szegedia@freemail.hu">Attila Szegedi</a>
49 * @author <a href="mailto:paulo.gaspar@krankikom.de">Paulo Gaspar</a>
50 * @version $Id: Introspector.java,v 1.6 2004/08/23 13:50:00 dion Exp $
51 */
52 public class Introspector extends IntrospectorBase
53 {
54 /***
55 * define a public string so that it can be looked for
56 * if interested
57 */
58
59 public static final String CACHEDUMP_MSG =
60 "Introspector : detected classloader change. Dumping cache.";
61
62 /***
63 * our engine runtime services
64 */
65 private Log rlog = null;
66
67 /***
68 * Recieves our RuntimeServices object
69 */
70 public Introspector(Log logger)
71 {
72 this.rlog = logger;
73 }
74
75 /***
76 * Gets the method defined by <code>name</code> and
77 * <code>params</code> for the Class <code>c</code>.
78 *
79 * @param c Class in which the method search is taking place
80 * @param name Name of the method being searched for
81 * @param params An array of Objects (not Classes) that describe the
82 * the parameters
83 *
84 * @return The desired Method object.
85 */
86 public Method getMethod(Class c, String name, Object[] params)
87 throws Exception
88 {
89
90
91
92
93 try
94 {
95 return super.getMethod( c, name, params );
96 }
97 catch( MethodMap.AmbiguousException ae )
98 {
99
100
101
102
103 String msg = "Introspection Error : Ambiguous method invocation "
104 + name + "( ";
105
106 for (int i = 0; i < params.length; i++)
107 {
108 if ( i > 0)
109 msg += ", ";
110
111 msg += params[i].getClass().getName();
112 }
113
114 msg = msg + ") for class " + c;
115
116 rlog.error( msg );
117 }
118
119 return null;
120 }
121
122 /***
123 * Clears the classmap and classname
124 * caches, and logs that we did so
125 */
126 protected void clearCache()
127 {
128 super.clearCache();
129 rlog.info( CACHEDUMP_MSG );
130 }
131 }