1 /*
2 * Copyright (c) 2005, 2016, 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.lang.reflect.InvocationTargetException;
29 import java.lang.reflect.Method;
30 import java.security.AccessController;
31 import java.security.PrivilegedAction;
32 import java.util.Iterator;
33 import java.util.ServiceConfigurationError;
34 import java.util.ServiceLoader;
35
36 /**
37 * Provides methods for locating tool providers, for example,
38 * providers of compilers. This class complements the
39 * functionality of {@link java.util.ServiceLoader}.
40 *
41 * @author Peter von der Ahé
42 * @since 1.6
43 */
44 public class ToolProvider {
45
46 private static final String systemJavaCompilerModule = "jdk.compiler";
47 private static final String systemJavaCompilerName = "com.sun.tools.javac.api.JavacTool";
48
49 /**
50 * Returns the Java™ programming language compiler provided
51 * with this platform.
52 * <p>The file manager returned by calling
53 * {@link JavaCompiler#getStandardFileManager getStandardFileManager}
54 * on this compiler supports paths provided by any
55 * {@linkplain java.nio.file.FileSystem filesystem}.</p>
56 * @return the compiler provided with this platform or
57 * {@code null} if no compiler is provided
58 * @implNote This implementation returns the compiler provided
59 * by the {@code jdk.compiler} module if that module is available,
60 * and null otherwise.
61 */
62 public static JavaCompiler getSystemJavaCompiler() {
63 return getSystemTool(JavaCompiler.class,
64 systemJavaCompilerModule, systemJavaCompilerName);
65 }
66
67 private static final String systemDocumentationToolModule = "jdk.javadoc";
68 private static final String systemDocumentationToolName = "jdk.javadoc.internal.api.JavadocTool";
69
70 /**
71 * Returns the Java™ programming language documentation tool provided
72 * with this platform.
73 * <p>The file manager returned by calling
74 * {@link DocumentationTool#getStandardFileManager getStandardFileManager}
75 * on this tool supports paths provided by any
76 * {@linkplain java.nio.file.FileSystem filesystem}.</p>
77 * @return the documentation tool provided with this platform or
78 * {@code null} if no documentation tool is provided
79 * @implNote This implementation returns the tool provided
80 * by the {@code jdk.javadoc} module if that module is available,
81 * and null otherwise.
82 */
83 public static DocumentationTool getSystemDocumentationTool() {
84 return getSystemTool(DocumentationTool.class,
85 systemDocumentationToolModule, systemDocumentationToolName);
86 }
87
88 /**
89 * Returns the class loader for tools provided with this platform.
90 * This does not include user-installed tools. Use the
91 * {@linkplain java.util.ServiceLoader service provider mechanism}
92 * for locating user installed tools.
93 *
94 * @return the class loader for tools provided with this platform
95 * or {@code null} if no tools are provided
96 */
97 public static ClassLoader getSystemToolClassLoader() {
98 return ClassLoader.getSystemClassLoader();
99 }
100
101 private static final boolean useLegacy;
102
103 static {
104 Class<?> c = null;
105 try {
106 c = Class.forName("java.lang.reflect.Module");
107 } catch (Throwable t) {
108 }
109 useLegacy = (c == null);
110 }
111
112 /**
113 * Get an instance of a system tool using the service loader.
114 * @implNote By default, this returns the implementation in the specified module.
115 * For limited backward compatibility, if this code is run on an older version
116 * of the Java platform that does not support modules, this method will
117 * try and create an instance of the named class. Note that implies the
118 * class must be available on the system class path.
119 * @param <T> the interface of the tool
120 * @param clazz the interface of the tool
121 * @param moduleName the name of the module containing the desired implementation
122 * @param className the class name of the desired implementation
123 * @return the specified implementation of the tool
124 */
125 private static <T> T getSystemTool(Class<T> clazz, String moduleName, String className) {
126 if (useLegacy) {
127 try {
128 return Class.forName(className, true, ClassLoader.getSystemClassLoader()).asSubclass(clazz).newInstance();
129 } catch (ReflectiveOperationException e) {
130 throw new Error(e);
131 }
132 }
133
134 try {
135 ServiceLoader<T> sl = ServiceLoader.load(clazz, ClassLoader.getSystemClassLoader());
136 for (Iterator<T> iter = sl.iterator(); iter.hasNext(); ) {
137 T tool = iter.next();
138 if (matches(tool, moduleName))
139 return tool;
140 }
141 } catch (ServiceConfigurationError e) {
142 throw new Error(e);
143 }
144 return null;
145 }
146
147 /**
148 * Determine if this is tho desired tool instance.
149 * @param <T> the interface of the tool
150 * @param tool the instance of the tool
151 * @param moduleName the name of the module containing the desired implementation
152 * @return true if and only if the tool matches the specified criteria
153 */
154 private static <T> boolean matches(T tool, String moduleName) {
155 PrivilegedAction<Boolean> pa = () -> {
156 // for now, use reflection to implement
157 // return moduleName.equals(tool.getClass().getModule().getName());
158 try {
159 Method getModuleMethod = Class.class.getDeclaredMethod("getModule");
160 Object toolModule = getModuleMethod.invoke(tool.getClass());
161 Method getNameMethod = toolModule.getClass().getDeclaredMethod("getName");
162 String toolModuleName = (String) getNameMethod.invoke(toolModule);
163 return moduleName.equals(toolModuleName);
164 } catch (InvocationTargetException | NoSuchMethodException | IllegalAccessException e) {
165 return false;
166 }
167 };
168 return AccessController.doPrivileged(pa);
169 }
170 }