1 /*
2 * Copyright 2010-2023 the original author or authors.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * https://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 package org.apache.ibatis.migration.io;
17
18 import java.io.File;
19 import java.io.IOException;
20 import java.io.InputStream;
21 import java.io.InputStreamReader;
22 import java.io.Reader;
23 import java.net.URL;
24 import java.net.URLConnection;
25 import java.nio.charset.Charset;
26 import java.util.Properties;
27
28 /**
29 * A class to simplify access to resources through the classloader.
30 *
31 * @author Clinton Begin
32 */
33 public class Resources {
34
35 private static ClassLoaderWrapper classLoaderWrapper = new ClassLoaderWrapper();
36
37 /**
38 * Charset to use when calling getResourceAsReader. null means use the system default.
39 */
40 private static Charset charset;
41
42 /**
43 * Returns the default classloader (may be null).
44 *
45 * @return The default classloader
46 */
47 public static ClassLoader getDefaultClassLoader() {
48 return classLoaderWrapper.defaultClassLoader;
49 }
50
51 /**
52 * Sets the default classloader
53 *
54 * @param defaultClassLoader
55 * - the new default ClassLoader
56 */
57 public static void setDefaultClassLoader(ClassLoader defaultClassLoader) {
58 classLoaderWrapper.defaultClassLoader = defaultClassLoader;
59 }
60
61 /**
62 * Returns the URL of the resource on the classpath
63 *
64 * @param resource
65 * The resource to find
66 *
67 * @return The resource
68 *
69 * @throws java.io.IOException
70 * If the resource cannot be found or read
71 */
72 public static URL getResourceURL(String resource) throws IOException {
73 // issue #625
74 return getResourceURL(null, resource);
75 }
76
77 /**
78 * Returns the URL of the resource on the classpath
79 *
80 * @param loader
81 * The classloader used to fetch the resource
82 * @param resource
83 * The resource to find
84 *
85 * @return The resource
86 *
87 * @throws java.io.IOException
88 * If the resource cannot be found or read
89 */
90 public static URL getResourceURL(ClassLoader loader, String resource) throws IOException {
91 URL url = classLoaderWrapper.getResourceAsURL(resource, loader);
92 if (url == null) {
93 throw new IOException("Could not find resource " + resource);
94 }
95 return url;
96 }
97
98 /**
99 * Returns a resource on the classpath as a Stream object
100 *
101 * @param resource
102 * The resource to find
103 *
104 * @return The resource
105 *
106 * @throws java.io.IOException
107 * If the resource cannot be found or read
108 */
109 public static InputStream getResourceAsStream(String resource) throws IOException {
110 return getResourceAsStream(null, resource);
111 }
112
113 /**
114 * Returns a resource on the classpath as a Stream object
115 *
116 * @param loader
117 * The classloader used to fetch the resource
118 * @param resource
119 * The resource to find
120 *
121 * @return The resource
122 *
123 * @throws java.io.IOException
124 * If the resource cannot be found or read
125 */
126 public static InputStream getResourceAsStream(ClassLoader loader, String resource) throws IOException {
127 InputStream in = classLoaderWrapper.getResourceAsStream(resource, loader);
128 if (in == null) {
129 throw new IOException("Could not find resource " + resource);
130 }
131 return in;
132 }
133
134 /**
135 * Returns a resource on the classpath as a Properties object
136 *
137 * @param resource
138 * The resource to find
139 *
140 * @return The resource
141 *
142 * @throws java.io.IOException
143 * If the resource cannot be found or read
144 */
145 public static Properties getResourceAsProperties(String resource) throws IOException {
146 Properties props = new Properties();
147 try (InputStream in = getResourceAsStream(resource)) {
148 props.load(in);
149 }
150 return props;
151 }
152
153 /**
154 * Returns a resource on the classpath as a Properties object
155 *
156 * @param loader
157 * The classloader used to fetch the resource
158 * @param resource
159 * The resource to find
160 *
161 * @return The resource
162 *
163 * @throws java.io.IOException
164 * If the resource cannot be found or read
165 */
166 public static Properties getResourceAsProperties(ClassLoader loader, String resource) throws IOException {
167 Properties props = new Properties();
168 try (InputStream in = getResourceAsStream(loader, resource)) {
169 props.load(in);
170 }
171 return props;
172 }
173
174 /**
175 * Returns a resource on the classpath as a Reader object
176 *
177 * @param resource
178 * The resource to find
179 *
180 * @return The resource
181 *
182 * @throws java.io.IOException
183 * If the resource cannot be found or read
184 */
185 public static Reader getResourceAsReader(String resource) throws IOException {
186 Reader reader;
187 if (charset == null) {
188 reader = new InputStreamReader(getResourceAsStream(resource));
189 } else {
190 reader = new InputStreamReader(getResourceAsStream(resource), charset);
191 }
192 return reader;
193 }
194
195 /**
196 * Returns a resource on the classpath as a Reader object
197 *
198 * @param loader
199 * The classloader used to fetch the resource
200 * @param resource
201 * The resource to find
202 *
203 * @return The resource
204 *
205 * @throws java.io.IOException
206 * If the resource cannot be found or read
207 */
208 public static Reader getResourceAsReader(ClassLoader loader, String resource) throws IOException {
209 Reader reader;
210 if (charset == null) {
211 reader = new InputStreamReader(getResourceAsStream(loader, resource));
212 } else {
213 reader = new InputStreamReader(getResourceAsStream(loader, resource), charset);
214 }
215 return reader;
216 }
217
218 /**
219 * Returns a resource on the classpath as a File object
220 *
221 * @param resource
222 * The resource to find
223 *
224 * @return The resource
225 *
226 * @throws java.io.IOException
227 * If the resource cannot be found or read
228 */
229 public static File getResourceAsFile(String resource) throws IOException {
230 return new File(getResourceURL(resource).getFile());
231 }
232
233 /**
234 * Returns a resource on the classpath as a File object
235 *
236 * @param loader
237 * - the classloader used to fetch the resource
238 * @param resource
239 * - the resource to find
240 *
241 * @return The resource
242 *
243 * @throws java.io.IOException
244 * If the resource cannot be found or read
245 */
246 public static File getResourceAsFile(ClassLoader loader, String resource) throws IOException {
247 return new File(getResourceURL(loader, resource).getFile());
248 }
249
250 /**
251 * Gets a URL as an input stream
252 *
253 * @param urlString
254 * - the URL to get
255 *
256 * @return An input stream with the data from the URL
257 *
258 * @throws java.io.IOException
259 * If the resource cannot be found or read
260 */
261 public static InputStream getUrlAsStream(String urlString) throws IOException {
262 URL url = new URL(urlString);
263 URLConnection conn = url.openConnection();
264 return conn.getInputStream();
265 }
266
267 /**
268 * Gets a URL as a Reader
269 *
270 * @param urlString
271 * - the URL to get
272 *
273 * @return A Reader with the data from the URL
274 *
275 * @throws java.io.IOException
276 * If the resource cannot be found or read
277 */
278 public static Reader getUrlAsReader(String urlString) throws IOException {
279 Reader reader;
280 if (charset == null) {
281 reader = new InputStreamReader(getUrlAsStream(urlString));
282 } else {
283 reader = new InputStreamReader(getUrlAsStream(urlString), charset);
284 }
285 return reader;
286 }
287
288 /**
289 * Gets a URL as a Properties object
290 *
291 * @param urlString
292 * - the URL to get
293 *
294 * @return A Properties object with the data from the URL
295 *
296 * @throws java.io.IOException
297 * If the resource cannot be found or read
298 */
299 public static Properties getUrlAsProperties(String urlString) throws IOException {
300 Properties props = new Properties();
301 try (InputStream in = getUrlAsStream(urlString)) {
302 props.load(in);
303 }
304 return props;
305 }
306
307 /**
308 * Loads a class
309 *
310 * @param className
311 * - the class to fetch
312 *
313 * @return The loaded class
314 *
315 * @throws ClassNotFoundException
316 * If the class cannot be found (duh!)
317 */
318 public static Class<?> classForName(String className) throws ClassNotFoundException {
319 return classLoaderWrapper.classForName(className);
320 }
321
322 public static Charset getCharset() {
323 return charset;
324 }
325
326 public static void setCharset(Charset charset) {
327 Resources.charset = charset;
328 }
329
330 }