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.text.lookup;
19
20 import java.util.MissingResourceException;
21 import java.util.ResourceBundle;
22
23 /**
24 * Looks up keys from resource bundles.
25 * <p>
26 * Looks up the value for a given key in the format "BundleName:BundleKey".
27 * </p>
28 * <p>
29 * For example: "com.domain.messages:MyKey".
30 * </p>
31 *
32 * @see ResourceBundle
33 * @since 1.3
34 */
35 final class ResourceBundleStringLookup extends AbstractStringLookup {
36
37 /**
38 * Defines the singleton for this class.
39 */
40 static final ResourceBundleStringLookup INSTANCE = new ResourceBundleStringLookup();
41
42 /**
43 * The name of the resource bundle from which to look something up.
44 */
45 private final String bundleName;
46
47 /**
48 * Constructs a blank instance.
49 */
50 private ResourceBundleStringLookup() {
51 this(null);
52 }
53
54 /**
55 * Constructs an instance that only works for the given bundle.
56 *
57 * @param bundleName the name of the resource bundle from which we will look keys up.
58 * @since 1.5
59 */
60 ResourceBundleStringLookup(final String bundleName) {
61 this.bundleName = bundleName;
62 }
63
64 ResourceBundle getBundle(final String keyBundleName) {
65 // The ResourceBundle class caches bundles, no need to cache here.
66 return ResourceBundle.getBundle(keyBundleName);
67 }
68
69 String getString(final String keyBundleName, final String bundleKey) {
70 return getBundle(keyBundleName).getString(bundleKey);
71 }
72
73 /**
74 * Looks up the value for the key in the format "BundleName:BundleKey".
75 *
76 * For example: "com.domain.messages:MyKey".
77 *
78 * @param key the key to be looked up, may be null
79 * @return The value associated with the key.
80 * @see ResourceBundle
81 * @see ResourceBundle#getBundle(String)
82 * @see ResourceBundle#getString(String)
83 */
84 @Override
85 public String lookup(final String key) {
86 if (key == null) {
87 return null;
88 }
89 final String[] keys = key.split(SPLIT_STR);
90 final int keyLen = keys.length;
91 final boolean anyBundle = bundleName == null;
92 if (anyBundle && keyLen != 2) {
93 throw IllegalArgumentExceptions
94 .format("Bad resource bundle key format [%s]; expected format is BundleName:KeyName.", key);
95 }
96 if (bundleName != null && keyLen != 1) {
97 throw IllegalArgumentExceptions.format("Bad resource bundle key format [%s]; expected format is KeyName.",
98 key);
99 }
100 final String keyBundleName = anyBundle ? keys[0] : bundleName;
101 final String bundleKey = anyBundle ? keys[1] : keys[0];
102 try {
103 return getString(keyBundleName, bundleKey);
104 } catch (final MissingResourceException e) {
105 // The key is missing, return null such that an interpolator can supply a default value.
106 return null;
107 } catch (final Exception e) {
108 // Should only be a ClassCastException
109 throw IllegalArgumentExceptions.format(e, "Error looking up resource bundle [%s] and key [%s].",
110 keyBundleName, bundleKey);
111 }
112 }
113
114 @Override
115 public String toString() {
116 return super.toString() + " [bundleName=" + bundleName + "]";
117 }
118
119 }