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
20 import static java.lang.reflect.Modifier.isFinal;
21 import static java.lang.reflect.Modifier.isStatic;
22
23 import java.lang.reflect.Field;
24
25 import org.apache.commons.jexl3.introspection.JexlPropertyGet;
26
27 /**
28 * A JexlPropertyGet for public fields.
29 */
30 public final class FieldGetExecutor implements JexlPropertyGet {
31 /**
32 * Attempts to discover a FieldGetExecutor.
33 *
34 * @param is the introspector
35 * @param clazz the class to find the get method from
36 * @param identifier the key to use as an argument to the get method
37 * @return the executor if found, null otherwise
38 */
39 public static JexlPropertyGet discover(final Introspector is, final Class<?> clazz, final String identifier) {
40 if (identifier != null) {
41 final Field field = is.getField(clazz, identifier);
42 if (field != null) {
43 return new FieldGetExecutor(field);
44 }
45 }
46 return null;
47 }
48
49 /**
50 * The public field.
51 */
52 private final Field field;
53 /**
54 * Creates a new instance of FieldPropertyGet.
55 * @param theField the class public field
56 */
57 private FieldGetExecutor(final Field theField) {
58 field = theField;
59 }
60
61 @Override
62 public Object invoke(final Object obj) throws Exception {
63 return field.get(obj);
64 }
65
66 @Override
67 public boolean isCacheable() {
68 return true;
69 }
70
71 @Override
72 public boolean isConstant() {
73 if (field.isEnumConstant()) {
74 return true;
75 }
76 final int modifiers = field.getModifiers();
77 // public static final fields are (considered) constants
78 return isFinal(modifiers) && isStatic(modifiers);
79 }
80
81 @Override
82 public boolean tryFailed(final Object rval) {
83 return rval == Uberspect.TRY_FAILED;
84 }
85
86 @Override
87 public Object tryInvoke(final Object obj, final Object key) {
88 if (obj.getClass().equals(field.getDeclaringClass()) && key.equals(field.getName())) {
89 try {
90 return field.get(obj);
91 } catch (final IllegalAccessException xill) {
92 return Uberspect.TRY_FAILED;
93 }
94 }
95 return Uberspect.TRY_FAILED;
96 }
97
98 }