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 package org.apache.commons.text.lookup;
18
19 import java.text.DateFormat;
20 import java.text.SimpleDateFormat;
21 import java.util.Date;
22
23 import org.apache.commons.lang3.time.FastDateFormat;
24 import org.apache.commons.text.StringSubstitutor;
25
26 /**
27 * Formats the current date with the format given in the key in a format compatible with
28 * {@link java.text.SimpleDateFormat}.
29 * <p>
30 * Using a {@link StringLookup} from the {@link StringLookupFactory}:
31 * </p>
32 *
33 * <pre>
34 * StringLookupFactory.INSTANCE.dateStringLookup().lookup("yyyy-MM-dd");
35 * </pre>
36 * <p>
37 * Using a {@link StringSubstitutor}:
38 * </p>
39 *
40 * <pre>
41 * StringSubstitutor.createInterpolator().replace("... ${date:yyyy-MM-dd} ..."));
42 * </pre>
43 * <p>
44 * The above examples convert {@code "yyyy-MM-dd"} to today's date, for example, {@code "2019-08-04"}.
45 * </p>
46 */
47 final class DateStringLookup extends AbstractStringLookup {
48
49 /**
50 * Defines the singleton for this class.
51 */
52 static final DateStringLookup INSTANCE = new DateStringLookup();
53
54 /**
55 * No need to build instances for now.
56 */
57 private DateStringLookup() {
58 // empty
59 }
60
61 /**
62 * Formats the given {@code date} long with the given {@code format}.
63 *
64 * @param dateMillis the date to format
65 * @param format the format string for {@link SimpleDateFormat}.
66 * @return The formatted date
67 */
68 private String formatDate(final long dateMillis, final String format) {
69 FastDateFormat dateFormat = null;
70 if (format != null) {
71 try {
72 dateFormat = FastDateFormat.getInstance(format);
73 } catch (final Exception ex) {
74 throw IllegalArgumentExceptions.format(ex, "Invalid date format: [%s]", format);
75 }
76 }
77 if (dateFormat == null) {
78 dateFormat = FastDateFormat.getInstance();
79 }
80 return dateFormat.format(new Date(dateMillis));
81 }
82
83 /**
84 * Formats the current date with the format given in the key in a format compatible with
85 * {@link java.text.SimpleDateFormat}.
86 *
87 * @param key the format to use. If null, the default {@link DateFormat} will be used.
88 * @return The value of the environment variable.
89 */
90 @Override
91 public String lookup(final String key) {
92 return formatDate(System.currentTimeMillis(), key);
93 }
94 }