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Java > Open Source Codes > org > apache > commons > jxpath > functions > MethodFunction


1 /*
2  * Copyright 1999-2004 The Apache Software Foundation
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package org.apache.commons.jxpath.functions;
17
18 import java.lang.reflect.InvocationTargetException JavaDoc;
19 import java.lang.reflect.Method JavaDoc;
20 import java.lang.reflect.Modifier JavaDoc;
21
22 import org.apache.commons.jxpath.ExpressionContext;
23 import org.apache.commons.jxpath.Function;
24 import org.apache.commons.jxpath.JXPathException;
25 import org.apache.commons.jxpath.util.TypeUtils;
26 import org.apache.commons.jxpath.util.ValueUtils;
27
28 /**
29  * An XPath extension function implemented as an individual Java method.
30  *
31  * @author Dmitri Plotnikov
32  * @version $Revision: 1.11 $ $Date: 2004/02/29 14:17:44 $
33  */
34 public class MethodFunction implements Function {
35
36     private Method JavaDoc method;
37     private static final Object JavaDoc EMPTY_ARRAY[] = new Object JavaDoc[0];
38
39     public MethodFunction(Method JavaDoc method) {
40         this.method = ValueUtils.getAccessibleMethod(method);
41     }
42
43     public Object JavaDoc invoke(ExpressionContext context, Object JavaDoc[] parameters) {
44         try {
45             Object JavaDoc target;
46             Object JavaDoc[] args;
47             if (Modifier.isStatic(method.getModifiers())) {
48                 target = null;
49                 if (parameters == null) {
50                     parameters = EMPTY_ARRAY;
51                 }
52                 int pi = 0;
53                 Class JavaDoc types[] = method.getParameterTypes();
54                 if (types.length >= 1
55                     && ExpressionContext.class.isAssignableFrom(types[0])) {
56                     pi = 1;
57                 }
58                 args = new Object JavaDoc[parameters.length + pi];
59                 if (pi == 1) {
60                     args[0] = context;
61                 }
62                 for (int i = 0; i < parameters.length; i++) {
63                     args[i + pi] =
64                         TypeUtils.convert(parameters[i], types[i + pi]);
65                 }
66             }
67             else {
68                 int pi = 0;
69                 Class JavaDoc types[] = method.getParameterTypes();
70                 if (types.length >= 1
71                     && ExpressionContext.class.isAssignableFrom(types[0])) {
72                     pi = 1;
73                 }
74                 target =
75                     TypeUtils.convert(
76                         parameters[0],
77                         method.getDeclaringClass());
78                 args = new Object JavaDoc[parameters.length - 1 + pi];
79                 if (pi == 1) {
80                     args[0] = context;
81                 }
82                 for (int i = 1; i < parameters.length; i++) {
83                     args[pi + i - 1] =
84                         TypeUtils.convert(parameters[i], types[i + pi - 1]);
85                 }
86             }
87
88             return method.invoke(target, args);
89         }
90         catch (Throwable JavaDoc ex) {
91             if (ex instanceof InvocationTargetException JavaDoc) {
92                 ex = ((InvocationTargetException JavaDoc) ex).getTargetException();
93             }
94             throw new JXPathException("Cannot invoke " + method, ex);
95         }
96     }
97     
98     public String JavaDoc toString() {
99         return method.toString();
100     }
101 }
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