1 /*
2 * Copyright (c) 2005, 2015, 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.ref.Reference;
29 import java.lang.ref.WeakReference;
30 import java.util.HashMap;
31 import java.util.Locale;
32 import java.util.Map;
33 import java.util.logging.Logger;
34 import java.util.logging.Level;
35
36 import static java.util.logging.Level.*;
37
38 /**
39 * Provides methods for locating tool providers, for example,
40 * providers of compilers. This class complements the
41 * functionality of {@link java.util.ServiceLoader}.
42 *
43 * @author Peter von der Ahé
44 * @since 1.6
45 */
46 public class ToolProvider {
47
48 private static final String propertyName = "sun.tools.ToolProvider";
49 private static final String loggerName = "javax.tools";
50
51 /*
52 * Define the system property "sun.tools.ToolProvider" to enable
53 * debugging:
54 *
55 * java ... -Dsun.tools.ToolProvider ...
56 */
57 static <T> T trace(Level level, Object reason) {
58 // NOTE: do not make this method private as it affects stack traces
59 try {
60 if (System.getProperty(propertyName) != null) {
61 StackTraceElement[] st = Thread.currentThread().getStackTrace();
62 String method = "???";
63 String cls = ToolProvider.class.getName();
64 if (st.length > 2) {
65 StackTraceElement frame = st[2];
66 method = String.format((Locale)null, "%s(%s:%s)",
67 frame.getMethodName(),
68 frame.getFileName(),
69 frame.getLineNumber());
70 cls = frame.getClassName();
71 }
72 Logger logger = Logger.getLogger(loggerName);
73 if (reason instanceof Throwable) {
74 logger.logp(level, cls, method,
75 reason.getClass().getName(), (Throwable)reason);
76 } else {
77 logger.logp(level, cls, method, String.valueOf(reason));
78 }
79 }
80 } catch (SecurityException ex) {
81 System.err.format((Locale)null, "%s: %s; %s%n",
82 ToolProvider.class.getName(),
83 reason,
84 ex.getLocalizedMessage());
85 }
86 return null;
87 }
88
89 private static final String systemJavaCompilerName
90 = "com.sun.tools.javac.api.JavacTool";
91
92 /**
93 * Returns the Java™ programming language compiler provided
94 * with this platform.
95 * <p>The file manager returned by calling
96 * {@link JavaCompiler#getStandardFileManager getStandardFileManager}
97 * on this compiler supports paths provided by any
98 * {@linkplain java.nio.file.FileSystem filesystem}.</p>
99 * @return the compiler provided with this platform or
100 * {@code null} if no compiler is provided
101 */
102 public static JavaCompiler getSystemJavaCompiler() {
103 return instance().getSystemTool(JavaCompiler.class, systemJavaCompilerName);
104 }
105
106 private static final String systemDocumentationToolName
107 = "jdk.javadoc.internal.api.JavadocTool";
108
109 /**
110 * Returns the Java™ programming language documentation tool provided
111 * with this platform.
112 * <p>The file manager returned by calling
113 * {@link DocumentationTool#getStandardFileManager getStandardFileManager}
114 * on this tool supports paths provided by any
115 * {@linkplain java.nio.file.FileSystem filesystem}.</p>
116 * @return the documentation tool provided with this platform or
117 * {@code null} if no documentation tool is provided
118 */
119 public static DocumentationTool getSystemDocumentationTool() {
120 return instance().getSystemTool(DocumentationTool.class, systemDocumentationToolName);
121 }
122
123 /**
124 * Returns the class loader for tools provided with this platform.
125 * This does not include user-installed tools. Use the
126 * {@linkplain java.util.ServiceLoader service provider mechanism}
127 * for locating user installed tools.
128 *
129 * @return the class loader for tools provided with this platform
130 * or {@code null} if no tools are provided
131 */
132 public static ClassLoader getSystemToolClassLoader() {
133 return ClassLoader.getSystemClassLoader();
134 }
135
136
137 private static ToolProvider instance;
138
139 private static synchronized ToolProvider instance() {
140 if (instance == null)
141 instance = new ToolProvider();
142 return instance;
143 }
144
145 // Cache for tool classes.
146 // Use weak references to avoid keeping classes around unnecessarily
147 private final Map<String, Reference<Class<?>>> toolClasses = new HashMap<>();
148
149 private ToolProvider() { }
150
151 private <T> T getSystemTool(Class<T> clazz, String name) {
152 Class<? extends T> c = getSystemToolClass(clazz, name);
153 try {
154 return c.asSubclass(clazz).newInstance();
155 } catch (InstantiationException | IllegalAccessException | RuntimeException | Error e) {
156 return trace(WARNING, e);
157 }
158 }
159
160 private <T> Class<? extends T> getSystemToolClass(Class<T> clazz, String name) {
161 Reference<Class<?>> refClass = toolClasses.get(name);
162 Class<?> c = (refClass == null ? null : refClass.get());
163 if (c == null) {
164 try {
165 c = Class.forName(name, false, ClassLoader.getSystemClassLoader());
166 } catch (ClassNotFoundException | RuntimeException | Error e) {
167 return trace(WARNING, e);
168 }
169 toolClasses.put(name, new WeakReference<>(c));
170 }
171 return c.asSubclass(clazz);
172 }
173 }