1 package org.codehaus.mojo.javacc;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import java.io.File;
23 import java.net.MalformedURLException;
24 import java.net.URL;
25 import java.nio.ByteBuffer;
26 import java.nio.charset.Charset;
27
28 /**
29 * Assists in handling of URLs.
30 *
31 * @author Benjamin Bentmann
32 * @version $Id$
33 */
34 class UrlUtils
35 {
36
37 /**
38 * The UTF-8 character set, used to decode octets in URLs.
39 */
40 private static final Charset UTF8 = Charset.forName( "UTF-8" );
41
42 /**
43 * The protocol prefix for "jar:" URLs.
44 */
45 private static final String JAR = "jar:";
46
47 /**
48 * The protocol prefix for "file:" URLs.
49 */
50 private static final String FILE = "file:";
51
52 /**
53 * The protocol prefix for "jar:file:" URLs.
54 */
55 private static final String JAR_FILE = JAR + FILE;
56
57 /**
58 * Gets the absolute filesystem path to the class path root for the specified resource. The root is either a JAR
59 * file or a directory with loose class files. If the URL does not use a supported protocol, an exception will be
60 * thrown.
61 *
62 * @param url The URL to the resource, may be <code>null</code>.
63 * @param resource The name of the resource, must not be <code>null</code>.
64 * @return The absolute filesystem path to the class path root of the resource or <code>null</code> if the input
65 * URL was <code>null</code>.
66 */
67 public static File getResourceRoot( URL url, String resource )
68 {
69 String path = null;
70 if ( url != null )
71 {
72 String spec = url.toExternalForm();
73 if ( ( JAR_FILE ).regionMatches( true, 0, spec, 0, JAR_FILE.length() ) )
74 {
75 URL jar;
76 try
77 {
78 jar = new URL( spec.substring( JAR.length(), spec.lastIndexOf( "!/" ) ) );
79 }
80 catch ( MalformedURLException e )
81 {
82 throw new IllegalArgumentException( "Invalid JAR URL: " + url + ", " + e.getMessage() );
83 }
84 path = decodeUrl( jar.getPath() );
85 }
86 else if ( FILE.regionMatches( true, 0, spec, 0, FILE.length() ) )
87 {
88 path = decodeUrl( url.getPath() );
89 path = path.substring( 0, path.length() - resource.length() );
90 }
91 else
92 {
93 throw new IllegalArgumentException( "Invalid class path URL: " + url );
94 }
95 }
96 return ( path != null ) ? new File( path ) : null;
97 }
98
99 /**
100 * Decodes the specified URL as per RFC 3986, i.e. transforms percent-encoded octets to characters by decoding with
101 * the UTF-8 character set. This function is primarily intended for usage with {@link java.net.URL} which
102 * unfortunately does not enforce proper URLs. As such, this method will leniently accept invalid characters or
103 * malformed percent-encoded octets and simply pass them literally through to the result string. Except for rare
104 * edge cases, this will make unencoded URLs pass through unaltered.
105 *
106 * @param url The URL to decode, may be <code>null</code>.
107 * @return The decoded URL or <code>null</code> if the input was <code>null</code>.
108 */
109 public static String decodeUrl( String url )
110 {
111 String decoded = url;
112 if ( url != null && url.indexOf( '%' ) >= 0 )
113 {
114 int n = url.length();
115 StringBuffer buffer = new StringBuffer();
116 ByteBuffer bytes = ByteBuffer.allocate( n );
117 for ( int i = 0; i < n; )
118 {
119 if ( url.charAt( i ) == '%' )
120 {
121 try
122 {
123 do
124 {
125 byte octet = (byte) Integer.parseInt( url.substring( i + 1, i + 3 ), 16 );
126 bytes.put( octet );
127 i += 3;
128 }
129 while ( i < n && url.charAt( i ) == '%' );
130 continue;
131 }
132 catch ( RuntimeException e )
133 {
134 // malformed percent-encoded octet, fall through and append characters literally
135 }
136 finally
137 {
138 if ( bytes.position() > 0 )
139 {
140 bytes.flip();
141 buffer.append( UTF8.decode( bytes ).toString() );
142 bytes.clear();
143 }
144 }
145 }
146 buffer.append( url.charAt( i++ ) );
147 }
148 decoded = buffer.toString();
149 }
150 return decoded;
151 }
152
153 }