1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.jexl3.internal.introspection;
19 import java.lang.reflect.InvocationTargetException;
20 import org.apache.commons.jexl3.JexlException;
21
22 /**
23 * Specialized executor to get a property from an object.
24 * @since 2.0
25 */
26 public final class PropertyGetExecutor extends AbstractExecutor.Get {
27 /** A static signature for method(). */
28 private static final Object[] EMPTY_PARAMS = {};
29 /** The property. */
30 private final String property;
31
32 /**
33 * Discovers a PropertyGetExecutor.
34 * <p>The method to be found should be named "get{P,p}property.</p>
35 *
36 * @param is the introspector
37 * @param clazz the class to find the get method from
38 * @param property the property name to find
39 * @return the executor if found, null otherwise
40 */
41 public static PropertyGetExecutor discover(final Introspector is, final Class<?> clazz, final String property) {
42 final java.lang.reflect.Method method = discoverGet(is, "get", clazz, property);
43 return method == null? null : new PropertyGetExecutor(clazz, method, property);
44 }
45
46 /**
47 * Creates an instance.
48 * @param clazz he class the get method applies to
49 * @param method the method held by this executor
50 * @param identifier the property to get
51 */
52 private PropertyGetExecutor(final Class<?> clazz, final java.lang.reflect.Method method, final String identifier) {
53 super(clazz, method);
54 property = identifier;
55 }
56
57 @Override
58 public Object getTargetProperty() {
59 return property;
60 }
61
62 @Override
63 public Object invoke(final Object o) throws IllegalAccessException, InvocationTargetException {
64 return method == null ? null : method.invoke(o, (Object[]) null);
65 }
66
67 @Override
68 public Object tryInvoke(final Object o, final Object identifier) {
69 if (o != null && method != null
70 && property.equals(castString(identifier))
71 && objectClass.equals(o.getClass())) {
72 try {
73 return method.invoke(o, (Object[]) null);
74 } catch (IllegalAccessException | IllegalArgumentException xill) {
75 return TRY_FAILED;// fail
76 } catch (final InvocationTargetException xinvoke) {
77 throw JexlException.tryFailed(xinvoke); // throw
78 }
79 }
80 return TRY_FAILED;
81 }
82
83 /**
84 * Base method for boolean and object property get.
85 * @param is the introspector
86 * @param which "is" or "get" for boolean or object
87 * @param clazz The class being examined.
88 * @param property The property being addressed.
89 * @return The {get,is}{p,P}roperty method if one exists, null otherwise.
90 */
91 static java.lang.reflect.Method discoverGet(final Introspector is,
92 final String which,
93 final Class<?> clazz,
94 final String property) {
95 if (property == null || property.isEmpty()) {
96 return null;
97 }
98 // this is gross and linear, but it keeps it straightforward.
99 java.lang.reflect.Method method;
100 final int start = which.length(); // "get" or "is" so 3 or 2 for char case switch
101 // start with get<Property>
102 final StringBuilder sb = new StringBuilder(which);
103 sb.append(property);
104 // uppercase nth char
105 final char c = sb.charAt(start);
106 sb.setCharAt(start, Character.toUpperCase(c));
107 method = is.getMethod(clazz, sb.toString(), EMPTY_PARAMS);
108 //lowercase nth char
109 if (method == null) {
110 sb.setCharAt(start, Character.toLowerCase(c));
111 method = is.getMethod(clazz, sb.toString(), EMPTY_PARAMS);
112 }
113 return method;
114 }
115 }
116