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 * https://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
21 import org.apache.commons.jexl3.JexlException;
22
23 /**
24 * Specialized executor to get a property from an object.
25 *
26 * @since 2.0
27 */
28 public final class PropertyGetExecutor extends AbstractExecutor.Get {
29
30 /** A static signature for method(). */
31 private static final Object[] EMPTY_PARAMS = {};
32
33 /**
34 * Discovers a PropertyGetExecutor.
35 * <p>The method to be found should be named "get{P,p}property.</p>
36 *
37 * @param is the introspector
38 * @param clazz the class to find the get method from
39 * @param property the property name to find
40 * @return the executor if found, null otherwise
41 */
42 public static PropertyGetExecutor discover(final Introspector is, final Class<?> clazz, final String property) {
43 final java.lang.reflect.Method method = discoverGet(is, "get", clazz, property);
44 return method == null ? null : new PropertyGetExecutor(clazz, method, property);
45 }
46
47 /**
48 * Base method for boolean and object property get.
49 *
50 * @param is the introspector
51 * @param which "is" or "get" for boolean or object
52 * @param clazz The class being examined.
53 * @param property The property being addressed.
54 * @return The {get,is}{p,P}roperty method if one exists, null otherwise.
55 */
56 static java.lang.reflect.Method discoverGet(final Introspector is,
57 final String which,
58 final Class<?> clazz,
59 final String property) {
60 if (property == null || property.isEmpty()) {
61 return null;
62 }
63 // this is gross and linear, but it keeps it straightforward.
64 java.lang.reflect.Method method;
65 final int start = which.length(); // "get" or "is" so 3 or 2 for char case switch
66 // start with get<Property>
67 final StringBuilder sb = new StringBuilder(which);
68 sb.append(property);
69 // uppercase nth char
70 final char c = sb.charAt(start);
71 sb.setCharAt(start, Character.toUpperCase(c));
72 method = is.getMethod(clazz, sb.toString(), EMPTY_PARAMS);
73 //lowercase nth char
74 if (method == null) {
75 sb.setCharAt(start, Character.toLowerCase(c));
76 method = is.getMethod(clazz, sb.toString(), EMPTY_PARAMS);
77 }
78 return method;
79 }
80
81 /** The property. */
82 private final String property;
83
84 /**
85 * Creates an instance.
86 *
87 * @param clazz he class the get method applies to
88 * @param method the method held by this executor
89 * @param identifier the property to get
90 */
91 private PropertyGetExecutor(final Class<?> clazz, final java.lang.reflect.Method method, final String identifier) {
92 super(clazz, method);
93 property = identifier;
94 }
95
96 @Override
97 public Object getTargetProperty() {
98 return property;
99 }
100
101 @Override
102 public Object invoke(final Object o) throws IllegalAccessException, InvocationTargetException {
103 return method == null ? null : method.invoke(o, (Object[]) null);
104 }
105
106 @Override
107 public Object tryInvoke(final Object o, final Object identifier) {
108 if (o != null && method != null
109 && property.equals(castString(identifier))
110 && objectClass.equals(o.getClass())) {
111 try {
112 return method.invoke(o, (Object[]) null);
113 } catch (IllegalAccessException | IllegalArgumentException xill) {
114 return TRY_FAILED; // fail
115 } catch (final InvocationTargetException xinvoke) {
116 throw JexlException.tryFailed(xinvoke); // throw
117 }
118 }
119 return TRY_FAILED;
120 }
121 }
122