1 /*
2 * Copyright (c) 2005, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package javax.tools;
27
28 import java.security.AccessController;
29 import java.security.PrivilegedAction;
30 import java.util.Iterator;
31 import java.util.ServiceConfigurationError;
32 import java.util.ServiceLoader;
33
34 /**
35 * Provides methods for locating tool providers, for example,
36 * providers of compilers. This class complements the
37 * functionality of {@link java.util.ServiceLoader}.
38 *
39 * @author Peter von der Ahé
40 * @since 1.6
41 */
42 public class ToolProvider {
43
44 private static final String systemJavaCompilerModule = "jdk.compiler";
45 private static final String systemJavaCompilerName = "com.sun.tools.javac.api.JavacTool";
46
47 /**
48 * Do not call.
49 */
50 @Deprecated(forRemoval=true, since="14")
51 public ToolProvider() {}
52
53 /**
54 * Returns the Java programming language compiler provided
55 * with this platform.
56 * <p>The file manager returned by calling
57 * {@link JavaCompiler#getStandardFileManager getStandardFileManager}
58 * on this compiler supports paths provided by any
59 * {@linkplain java.nio.file.FileSystem filesystem}.</p>
60 * @return the compiler provided with this platform or
61 * {@code null} if no compiler is provided
62 * @implNote This implementation returns the compiler provided
63 * by the {@code jdk.compiler} module if that module is available,
64 * and {@code null} otherwise.
65 */
66 public static JavaCompiler getSystemJavaCompiler() {
67 return getSystemTool(JavaCompiler.class,
68 systemJavaCompilerModule, systemJavaCompilerName);
69 }
70
71 private static final String systemDocumentationToolModule = "jdk.javadoc";
72 private static final String systemDocumentationToolName = "jdk.javadoc.internal.api.JavadocTool";
73
74 /**
75 * Returns the Java programming language documentation tool provided
76 * with this platform.
77 * <p>The file manager returned by calling
78 * {@link DocumentationTool#getStandardFileManager getStandardFileManager}
79 * on this tool supports paths provided by any
80 * {@linkplain java.nio.file.FileSystem filesystem}.</p>
81 * @return the documentation tool provided with this platform or
82 * {@code null} if no documentation tool is provided
83 * @implNote This implementation returns the tool provided
84 * by the {@code jdk.javadoc} module if that module is available,
85 * and {@code null} otherwise.
86 */
87 public static DocumentationTool getSystemDocumentationTool() {
88 return getSystemTool(DocumentationTool.class,
89 systemDocumentationToolModule, systemDocumentationToolName);
90 }
91
92 /**
93 * Returns a class loader that may be used to load system tools,
94 * or {@code null} if no such special loader is provided.
95 * @implSpec This implementation always returns {@code null}.
96 * @deprecated This method is subject to removal in a future version of
97 * Java SE.
98 * Use the {@link java.util.spi.ToolProvider system tool provider} or
99 * {@link java.util.ServiceLoader service loader} mechanisms to
100 * locate system tools as well as user-installed tools.
101 * @return a class loader, or {@code null}
102 */
103 @Deprecated(since="9")
104 public static ClassLoader getSystemToolClassLoader() {
105 return null;
106 }
107
108 /**
109 * Get an instance of a system tool using the service loader.
110 * @implNote By default, this returns the implementation in the specified module.
111 * For limited backward compatibility, if this code is run on an older version
112 * of the Java platform that does not support modules, this method will
113 * try and create an instance of the named class. Note that implies the
114 * class must be available on the system class path.
115 * @param <T> the interface of the tool
116 * @param clazz the interface of the tool
117 * @param moduleName the name of the module containing the desired implementation
118 * @param className the class name of the desired implementation
119 * @return the specified implementation of the tool
120 */
121 private static <T> T getSystemTool(Class<T> clazz, String moduleName, String className) {
122
123 try {
124 ServiceLoader<T> sl = ServiceLoader.load(clazz, ClassLoader.getSystemClassLoader());
125 for (Iterator<T> iter = sl.iterator(); iter.hasNext(); ) {
126 T tool = iter.next();
127 if (matches(tool, moduleName))
128 return tool;
129 }
130 } catch (ServiceConfigurationError e) {
131 throw new Error(e);
132 }
133 return null;
134 }
135
136 /**
137 * Determine if this is the desired tool instance.
138 * @param <T> the interface of the tool
139 * @param tool the instance of the tool
140 * @param moduleName the name of the module containing the desired implementation
141 * @return true if and only if the tool matches the specified criteria
142 */
143 private static <T> boolean matches(T tool, String moduleName) {
144 PrivilegedAction<Boolean> pa = () -> {
145 Module toolModule = tool.getClass().getModule();
146 String toolModuleName = toolModule.getName();
147 return toolModuleName.equals(moduleName);
148 };
149 return AccessController.doPrivileged(pa);
150 }
151 }