ResourceLoader


1   /*
2    * Copyright 2002-2007 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    *      http://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  
17  package org.springframework.core.io;
18  
19  import org.springframework.util.ResourceUtils;
20  
21  /**
22   * Strategy interface for loading resources (e.. class path or file system
23   * resources). An {@link org.springframework.context.ApplicationContext}
24   * is required to provide this functionality, plus extended
25   * {@link org.springframework.core.io.support.ResourcePatternResolver} support.
26   *
27   * <p>{@link DefaultResourceLoader} is a standalone implementation that is
28   * usable outside an ApplicationContext, also used by {@link ResourceEditor}.
29   *
30   * <p>Bean properties of type Resource and Resource array can be populated
31   * from Strings when running in an ApplicationContext, using the particular
32   * context's resource loading strategy.
33   *
34   * @author Juergen Hoeller
35   * @since 10.03.2004
36   * @see Resource
37   * @see org.springframework.core.io.support.ResourcePatternResolver
38   * @see org.springframework.context.ApplicationContext
39   * @see org.springframework.context.ResourceLoaderAware
40   */
41  public interface ResourceLoader {
42  
43      /** Pseudo URL prefix for loading from the class path: "classpath:" */
44      String   CLASSPATH_URL_PREFIX = ResourceUtils.CLASSPATH_URL_PREFIX;
45  
46  
47      /**
48       * Return a Resource handle for the specified resource.
49       * The handle should always be a reusable resource descriptor,
50       * allowing for multiple {@link Resource#getInputStream()} calls.
51       * <p><ul>
52       * <li>Must support fully qualified URLs, e.g. "file:C:/test.dat".
53       * <li>Must support classpath pseudo-URLs, e.g. "classpath:test.dat".
54       * <li>Should support relative file paths, e.g. "WEB-INF/test.dat".
55       * (This will be implementation-specific, typically provided by an
56       * ApplicationContext implementation.)
57       * </ul>
58       * <p>Note that a Resource handle does not imply an existing resource;
59       * you need to invoke {@link Resource#exists} to check for existence.
60       * @param location the resource location
61       * @return a corresponding Resource handle
62       * @see #CLASSPATH_URL_PREFIX
63       * @see org.springframework.core.io.Resource#exists
64       * @see org.springframework.core.io.Resource#getInputStream
65       */
66      Resource getResource(String   location);
67  
68      /**
69       * Expose the ClassLoader used by this ResourceLoader.
70       * <p>Clients which need to access the ClassLoader directly can do so
71       * in a uniform manner with the ResourceLoader, rather than relying
72       * on the thread context ClassLoader.
73       * @return the ClassLoader (never <code>null</code>)
74       */
75      ClassLoader   getClassLoader();
76  
77  }
78
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