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 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 * <p>
47 * Public access is through {@link StringLookupFactory}.
48 * </p>
49 *
50 * @see StringLookupFactory
51 */
52 final class DateStringLookup extends AbstractStringLookup {
53
54 /**
55 * Defines the singleton for this class.
56 */
57 static final DateStringLookup INSTANCE = new DateStringLookup();
58
59 /**
60 * No need to build instances for now.
61 */
62 private DateStringLookup() {
63 // empty
64 }
65
66 /**
67 * Formats the given {@code date} long with the given {@code format}.
68 *
69 * @param dateMillis the date to format.
70 * @param format the format string for {@link SimpleDateFormat}.
71 * @return The formatted date.
72 */
73 private String formatDate(final long dateMillis, final String format) {
74 FastDateFormat dateFormat = null;
75 if (format != null) {
76 try {
77 dateFormat = FastDateFormat.getInstance(format);
78 } catch (final Exception ex) {
79 throw IllegalArgumentExceptions.format(ex, "Invalid date format: [%s]", format);
80 }
81 }
82 if (dateFormat == null) {
83 dateFormat = FastDateFormat.getInstance();
84 }
85 return dateFormat.format(new Date(dateMillis));
86 }
87
88 /**
89 * Formats the current date with the format given in the key in a format compatible with
90 * {@link java.text.SimpleDateFormat}.
91 *
92 * @param key the format to use. If null, the default {@link DateFormat} will be used.
93 * @return The value of the environment variable.
94 */
95 @Override
96 public String lookup(final String key) {
97 return formatDate(System.currentTimeMillis(), key);
98 }
99 }