1 package org.apache.maven.plugin.surefire.booterclient;
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 javax.annotation.Nonnull;
23 import java.io.BufferedReader;
24 import java.io.IOException;
25 import java.io.InputStream;
26 import java.io.InputStreamReader;
27 import java.net.URL;
28 import java.util.Collections;
29 import java.util.Enumeration;
30 import java.util.HashSet;
31 import java.util.Set;
32
33 /**
34 * @author Stephen Conolly
35 * @author Kristian Rosenvold
36 * @noinspection UnusedDeclaration
37 */
38 public class ProviderDetector
39 {
40
41 @Nonnull public static Set<String> getServiceNames( Class<?> clazz, ClassLoader classLoader )
42 throws IOException
43 {
44 final String resourceName = "META-INF/services/" + clazz.getName();
45
46 if ( classLoader == null )
47 {
48 return Collections.emptySet();
49 }
50 final Enumeration<URL> urlEnumeration = classLoader.getResources( resourceName );
51 return getNames( urlEnumeration );
52 }
53
54
55 /**
56 * Method loadServices loads the services of a class that are
57 * defined using the SPI mechanism.
58 *
59 * @param urlEnumeration The urls from the resource
60 * @return The set of service provider names
61 * @throws IOException When reading the streams fails
62 */
63 @Nonnull private static Set<String> getNames( final Enumeration<URL> urlEnumeration )
64 throws IOException
65 {
66 final Set<String> names = new HashSet<String>();
67 nextUrl:
68 while ( urlEnumeration.hasMoreElements() )
69 {
70 final URL url = urlEnumeration.nextElement();
71 final BufferedReader reader = getReader( url );
72 try
73 {
74 String line;
75 while ( ( line = reader.readLine() ) != null )
76 {
77 int ci = line.indexOf( '#' );
78 if ( ci >= 0 )
79 {
80 line = line.substring( 0, ci );
81 }
82 line = line.trim();
83 int n = line.length();
84 if ( n == 0 )
85 {
86 continue; // next line
87 }
88
89 if ( ( line.indexOf( ' ' ) >= 0 ) || ( line.indexOf( '\t' ) >= 0 ) )
90 {
91 continue nextUrl; // next url
92 }
93 char cp = line.charAt( 0 ); // should use codePointAt but this is JDK1.3
94 if ( !Character.isJavaIdentifierStart( cp ) )
95 {
96 continue nextUrl; // next url
97 }
98 for ( int i = 1; i < n; i++ )
99 {
100 cp = line.charAt( i ); // should use codePointAt but this is JDK1.3
101 if ( !Character.isJavaIdentifierPart( cp ) && ( cp != '.' ) )
102 {
103 continue nextUrl; // next url
104 }
105 }
106 if ( !names.contains( line ) )
107 {
108 names.add( line );
109 }
110 }
111 }
112 finally
113 {
114 reader.close();
115 }
116 }
117
118 return names;
119 }
120
121 @Nonnull private static BufferedReader getReader( @Nonnull URL url )
122 throws IOException
123 {
124 final InputStream inputStream = url.openStream();
125 final InputStreamReader inputStreamReader = new InputStreamReader( inputStream );
126 return new BufferedReader( inputStreamReader );
127 }
128 }