1   /**
2    * Logback: the reliable, generic, fast and flexible logging framework.
3    * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
4    *
5    * This program and the accompanying materials are dual-licensed under
6    * either the terms of the Eclipse Public License v1.0 as published by
7    * the Eclipse Foundation
8    *
9    *   or (per the licensee's choosing)
10   *
11   * under the terms of the GNU Lesser General Public License version 2.1
12   * as published by the Free Software Foundation.
13   */
14  package ch.qos.logback.core.util;
15  
16  import java.io.FileNotFoundException;
17  import java.net.MalformedURLException;
18  import java.net.URL;
19  
20  /**
21   * A static utility method that converts a string that describes the location of
22   * a resource into a {@link URL} object.
23   *
24   * @author Carl Harris
25   */
26  public class LocationUtil {
27  
28      /** Regex pattern for a URL scheme (reference RFC 2396 section 3) */
29      public static final String SCHEME_PATTERN = "^\\p{Alpha}[\\p{Alnum}+.-]*:.*$";
30  
31      /** Scheme name for a classpath resource */
32      public static final String CLASSPATH_SCHEME = "classpath:";
33  
34      /**
35       * Converts a string describing the location of a resource into a URL object.
36       * 
37       * @param location String describing the location
38       * @return URL object that refers to {@code location}
39       * @throws MalformedURLException if {@code location} is not a syntactically valid
40       *                               URL
41       * @throws FileNotFoundException if {@code location} specifies a non-existent
42       *                               classpath resource
43       * @throws NullPointerException  if {@code location} is {@code null}
44       */
45      public static URL urlForResource(String location) throws MalformedURLException, FileNotFoundException {
46          if (location == null) {
47              throw new NullPointerException("location is required");
48          }
49          URL url = null;
50          if (!location.matches(SCHEME_PATTERN)) {
51              url = Loader.getResourceBySelfClassLoader(location);
52          } else if (location.startsWith(CLASSPATH_SCHEME)) {
53              String path = location.substring(CLASSPATH_SCHEME.length());
54              if (path.startsWith("/")) {
55                  path = path.substring(1);
56              }
57              if (path.length() == 0) {
58                  throw new MalformedURLException("path is required");
59              }
60              url = Loader.getResourceBySelfClassLoader(path);
61          } else {
62              url = new URL(location);
63          }
64          if (url == null) {
65              throw new FileNotFoundException(location);
66          }
67          return url;
68      }
69  
70  }