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 * Returns the Java programming language compiler provided
49 * with this platform.
50 * <p>The file manager returned by calling
51 * {@link JavaCompiler#getStandardFileManager getStandardFileManager}
52 * on this compiler supports paths provided by any
53 * {@linkplain java.nio.file.FileSystem filesystem}.</p>
54 * @return the compiler provided with this platform or
55 * {@code null} if no compiler is provided
56 * @implNote This implementation returns the compiler provided
57 * by the {@code jdk.compiler} module if that module is available,
58 * and {@code null} otherwise.
59 */
60 public static JavaCompiler getSystemJavaCompiler() {
61 return getSystemTool(JavaCompiler.class,
62 systemJavaCompilerModule, systemJavaCompilerName);
63 }
64
65 private static final String systemDocumentationToolModule = "jdk.javadoc";
66 private static final String systemDocumentationToolName = "jdk.javadoc.internal.api.JavadocTool";
67
68 /**
69 * Returns the Java programming language documentation tool provided
70 * with this platform.
71 * <p>The file manager returned by calling
72 * {@link DocumentationTool#getStandardFileManager getStandardFileManager}
73 * on this tool supports paths provided by any
74 * {@linkplain java.nio.file.FileSystem filesystem}.</p>
75 * @return the documentation tool provided with this platform or
76 * {@code null} if no documentation tool is provided
77 * @implNote This implementation returns the tool provided
78 * by the {@code jdk.javadoc} module if that module is available,
79 * and {@code null} otherwise.
80 */
81 public static DocumentationTool getSystemDocumentationTool() {
82 return getSystemTool(DocumentationTool.class,
83 systemDocumentationToolModule, systemDocumentationToolName);
84 }
85
86 /**
87 * Returns a class loader that may be used to load system tools,
88 * or {@code null} if no such special loader is provided.
89 * @implSpec This implementation always returns {@code null}.
90 * @deprecated This method is subject to removal in a future version of
91 * Java SE.
92 * Use the {@link java.util.spi.ToolProvider system tool provider} or
93 * {@link java.util.ServiceLoader service loader} mechanisms to
94 * locate system tools as well as user-installed tools.
95 * @return a class loader, or {@code null}
96 */
97 @Deprecated(since="9")
98 public static ClassLoader getSystemToolClassLoader() {
99 return null;
100 }
101
102 /**
103 * Get an instance of a system tool using the service loader.
104 * @implNote By default, this returns the implementation in the specified module.
105 * For limited backward compatibility, if this code is run on an older version
106 * of the Java platform that does not support modules, this method will
107 * try and create an instance of the named class. Note that implies the
108 * class must be available on the system class path.
109 * @param <T> the interface of the tool
110 * @param clazz the interface of the tool
111 * @param moduleName the name of the module containing the desired implementation
112 * @param className the class name of the desired implementation
113 * @return the specified implementation of the tool
114 */
115 private static <T> T getSystemTool(Class<T> clazz, String moduleName, String className) {
116
117 try {
118 ServiceLoader<T> sl = ServiceLoader.load(clazz, ClassLoader.getSystemClassLoader());
119 for (Iterator<T> iter = sl.iterator(); iter.hasNext(); ) {
120 T tool = iter.next();
121 if (matches(tool, moduleName))
122 return tool;
123 }
124 } catch (ServiceConfigurationError e) {
125 throw new Error(e);
126 }
127 return null;
128 }
129
130 /**
131 * Determine if this is the desired tool instance.
132 * @param <T> the interface of the tool
133 * @param tool the instance of the tool
134 * @param moduleName the name of the module containing the desired implementation
135 * @return true if and only if the tool matches the specified criteria
136 */
137 private static <T> boolean matches(T tool, String moduleName) {
138 PrivilegedAction<Boolean> pa = () -> {
139 Module toolModule = tool.getClass().getModule();
140 String toolModuleName = toolModule.getName();
141 return toolModuleName.equals(moduleName);
142 };
143 return AccessController.doPrivileged(pa);
144 }
145 }