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.text.lookup;
19
20 import java.nio.file.Files;
21 import java.nio.file.Path;
22
23 import org.apache.commons.lang3.StringUtils;
24 import org.apache.commons.text.StringSubstitutor;
25
26 /**
27 * Looks up file contents.
28 * <p>
29 * Using a {@link StringLookup} from the {@link StringLookupFactory}:
30 * </p>
31 *
32 * <pre>
33 * StringLookupFactory.INSTANCE.fileStringLookup().lookup("UTF-8:com/domain/document.properties");
34 * </pre>
35 * <p>
36 * The above example converts {@code "UTF-8:com/domain/document.properties"} to the UTF-8 contents of the file at {@code com/domain/document.properties}.
37 * </p>
38 * <p>
39 * Using a {@link StringSubstitutor}:
40 * </p>
41 *
42 * <pre>
43 * StringSubstitutor.createInterpolator().replace("... ${file:UTF-8:com/domain/document.properties} ..."));
44 * </pre>
45 * <p>
46 * The above example converts {@code "UTF-8:SomePath"} to the UTF-8 contents of the file at {@code SomePath}.
47 * </p>
48 * <p>
49 * Public access is through {@link StringLookupFactory}.
50 * </p>
51 *
52 * @see StringLookupFactory
53 * @since 1.5
54 */
55 final class FileStringLookup extends AbstractPathFencedLookup {
56
57 /**
58 * Defines the singleton for this class.
59 */
60 static final AbstractStringLookup INSTANCE = new FileStringLookup((Path[]) null);
61
62 /**
63 * Constructs a new instance.
64 *
65 * @param fences The fences guarding Path resolution.
66 */
67 FileStringLookup(final Path... fences) {
68 super(fences);
69 }
70
71 /**
72 * Looks up the value for the key in the format "charsetName:DocumentPath".
73 * <p>
74 * For example: "UTF-8:com/domain/document.properties".
75 * </p>
76 *
77 * @param key the key to be looked up, may be null
78 * @return The value associated with the key.
79 */
80 @Override
81 public String lookup(final String key) {
82 if (key == null) {
83 return null;
84 }
85 final String[] keys = key.split(String.valueOf(SPLIT_CH));
86 final int keyLen = keys.length;
87 if (keyLen < 2) {
88 throw IllegalArgumentExceptions.format("Bad file key format [%s], expected format is CharsetName:DocumentPath.", key);
89 }
90 final String charsetName = keys[0];
91 final String fileName = StringUtils.substringAfter(key, SPLIT_CH);
92 try {
93 return new String(Files.readAllBytes(getPath(fileName)), charsetName);
94 } catch (final Exception e) {
95 throw IllegalArgumentExceptions.format(e, "Error looking up file [%s] with charset [%s].", fileName, charsetName);
96 }
97 }
98
99 }