1 package org.apache.velocity.runtime.parser.node;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import java.lang.reflect.InvocationTargetException;
23
24 import org.apache.commons.lang.StringUtils;
25 import org.apache.velocity.exception.VelocityException;
26 import org.apache.velocity.runtime.RuntimeLogger;
27 import org.apache.velocity.runtime.log.Log;
28 import org.apache.velocity.runtime.log.RuntimeLoggerLog;
29 import org.apache.velocity.util.introspection.Introspector;
30
31 /**
32 * Returned the value of object property when executed.
33 */
34 public class PropertyExecutor extends AbstractExecutor
35 {
36 private final Introspector introspector;
37
38 /**
39 * @param log
40 * @param introspector
41 * @param clazz
42 * @param property
43 * @since 1.5
44 */
45 public PropertyExecutor(final Log log, final Introspector introspector,
46 final Class clazz, final String property)
47 {
48 this.log = log;
49 this.introspector = introspector;
50
51 // Don't allow passing in the empty string or null because
52 // it will either fail with a StringIndexOutOfBounds error
53 // or the introspector will get confused.
54 if (StringUtils.isNotEmpty(property))
55 {
56 discover(clazz, property);
57 }
58 }
59
60 /**
61 * @param r
62 * @param introspector
63 * @param clazz
64 * @param property
65 * @deprecated RuntimeLogger is deprecated. Use the other constructor.
66 */
67 public PropertyExecutor(final RuntimeLogger r, final Introspector introspector,
68 final Class clazz, final String property)
69 {
70 this(new RuntimeLoggerLog(r), introspector, clazz, property);
71 }
72
73 /**
74 * @return The current introspector.
75 * @since 1.5
76 */
77 protected Introspector getIntrospector()
78 {
79 return this.introspector;
80 }
81
82 /**
83 * @param clazz
84 * @param property
85 */
86 protected void discover(final Class clazz, final String property)
87 {
88 /*
89 * this is gross and linear, but it keeps it straightforward.
90 */
91
92 try
93 {
94 Object [] params = {};
95
96 StringBuffer sb = new StringBuffer("get");
97 sb.append(property);
98
99 setMethod(introspector.getMethod(clazz, sb.toString(), params));
100
101 if (!isAlive())
102 {
103 /*
104 * now the convenience, flip the 1st character
105 */
106
107 char c = sb.charAt(3);
108
109 if (Character.isLowerCase(c))
110 {
111 sb.setCharAt(3, Character.toUpperCase(c));
112 }
113 else
114 {
115 sb.setCharAt(3, Character.toLowerCase(c));
116 }
117
118 setMethod(introspector.getMethod(clazz, sb.toString(), params));
119 }
120 }
121 /**
122 * pass through application level runtime exceptions
123 */
124 catch( RuntimeException e )
125 {
126 throw e;
127 }
128 catch(Exception e)
129 {
130 String msg = "Exception while looking for property getter for '" + property;
131 log.error(msg, e);
132 throw new VelocityException(msg, e);
133 }
134 }
135
136 /**
137 * @see org.apache.velocity.runtime.parser.node.AbstractExecutor#execute(java.lang.Object)
138 */
139 public Object execute(Object o)
140 throws IllegalAccessException, InvocationTargetException
141 {
142 return isAlive() ? getMethod().invoke(o, ((Object []) null)) : null;
143 }
144 }