Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
QueryLoader |
|
| 1.6;1.6 |
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.dbutils; | |
18 | ||
19 | import java.io.IOException; | |
20 | import java.io.InputStream; | |
21 | import java.util.HashMap; | |
22 | import java.util.Map; | |
23 | import java.util.Properties; | |
24 | ||
25 | /** | |
26 | * <code>QueryLoader</code> is a registry for sets of queries so | |
27 | * that multiple copies of the same queries aren't loaded into memory. | |
28 | * This implementation loads properties files filled with query name to | |
29 | * SQL mappings. This class is thread safe. | |
30 | */ | |
31 | public class QueryLoader { | |
32 | ||
33 | /** | |
34 | * The Singleton instance of this class. | |
35 | */ | |
36 | 0 | private static final QueryLoader instance = new QueryLoader(); |
37 | ||
38 | /** | |
39 | * Return an instance of this class. | |
40 | * @return The Singleton instance. | |
41 | */ | |
42 | public static QueryLoader instance() { | |
43 | 0 | return instance; |
44 | } | |
45 | ||
46 | /** | |
47 | * Maps query set names to Maps of their queries. | |
48 | */ | |
49 | 0 | private final Map queries = new HashMap(); |
50 | ||
51 | /** | |
52 | * QueryLoader constructor. | |
53 | */ | |
54 | protected QueryLoader() { | |
55 | 0 | super(); |
56 | 0 | } |
57 | ||
58 | /** | |
59 | * Loads a Map of query names to SQL values. The Maps are cached so a | |
60 | * subsequent request to load queries from the same path will return | |
61 | * the cached Map. | |
62 | * | |
63 | * @param path The path that the ClassLoader will use to find the file. | |
64 | * This is <strong>not</strong> a file system path. If you had a jarred | |
65 | * Queries.properties file in the com.yourcorp.app.jdbc package you would | |
66 | * pass "/com/yourcorp/app/jdbc/Queries.properties" to this method. | |
67 | * @throws IOException if a file access error occurs | |
68 | * @throws IllegalArgumentException if the ClassLoader can't find a file at | |
69 | * the given path. | |
70 | * @return Map of query names to SQL values | |
71 | */ | |
72 | public synchronized Map load(String path) throws IOException { | |
73 | ||
74 | 0 | Map queryMap = (Map) this.queries.get(path); |
75 | ||
76 | 0 | if (queryMap == null) { |
77 | 0 | queryMap = this.loadQueries(path); |
78 | 0 | this.queries.put(path, queryMap); |
79 | } | |
80 | ||
81 | 0 | return queryMap; |
82 | } | |
83 | ||
84 | /** | |
85 | * Loads a set of named queries into a Map object. This implementation | |
86 | * reads a properties file at the given path. | |
87 | * @param path The path that the ClassLoader will use to find the file. | |
88 | * @throws IOException if a file access error occurs | |
89 | * @throws IllegalArgumentException if the ClassLoader can't find a file at | |
90 | * the given path. | |
91 | * @since DbUtils 1.1 | |
92 | * @return Map of query names to SQL values | |
93 | */ | |
94 | protected Map loadQueries(String path) throws IOException { | |
95 | 0 | InputStream in = getClass().getResourceAsStream(path); |
96 | ||
97 | 0 | if (in == null) { |
98 | 0 | throw new IllegalArgumentException(path + " not found."); |
99 | } | |
100 | ||
101 | 0 | Properties props = new Properties(); |
102 | 0 | props.load(in); |
103 | ||
104 | // Copy to HashMap for better performance | |
105 | 0 | return new HashMap(props); |
106 | } | |
107 | ||
108 | /** | |
109 | * Removes the queries for the given path from the cache. | |
110 | * @param path The path that the queries were loaded from. | |
111 | */ | |
112 | public synchronized void unload(String path){ | |
113 | 0 | this.queries.remove(path); |
114 | 0 | } |
115 | ||
116 | } |