1 /* 2 * Copyright (c) 2005, 2020, 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.Objects; 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 ToolProvider()47 private ToolProvider() {} 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 {@code null} otherwise. 61 */ getSystemJavaCompiler()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 {@code null} otherwise. 82 */ getSystemDocumentationTool()83 public static DocumentationTool getSystemDocumentationTool() { 84 return getSystemTool(DocumentationTool.class, 85 systemDocumentationToolModule, systemDocumentationToolName); 86 } 87 88 /** 89 * Returns a class loader that may be used to load system tools, 90 * or {@code null} if no such special loader is provided. 91 * @implSpec This implementation always returns {@code null}. 92 * @deprecated This method is subject to removal in a future version of 93 * Java SE. 94 * Use the {@link java.util.spi.ToolProvider system tool provider} or 95 * {@link java.util.ServiceLoader service loader} mechanisms to 96 * locate system tools as well as user-installed tools. 97 * @return a class loader, or {@code null} 98 */ 99 @Deprecated(since="9") getSystemToolClassLoader()100 public static ClassLoader getSystemToolClassLoader() { 101 return null; 102 } 103 104 /** 105 * Get an instance of a system tool using the service loader. 106 * @implNote By default, this returns the implementation in the specified module. 107 * For limited backward compatibility, if this code is run on an older version 108 * of the Java platform that does not support modules, this method will 109 * try and create an instance of the named class. Note that implies the 110 * class must be available on the system class path. 111 * @param <T> the interface of the tool 112 * @param clazz the interface of the tool 113 * @param moduleName the name of the module containing the desired implementation 114 * @param className the class name of the desired implementation 115 * @return the specified implementation of the tool 116 */ getSystemTool(Class<T> clazz, String moduleName, String className)117 private static <T> T getSystemTool(Class<T> clazz, String moduleName, String className) { 118 119 try { 120 ServiceLoader<T> sl = ServiceLoader.load(clazz, ClassLoader.getSystemClassLoader()); 121 for (T tool : sl) { 122 if (matches(tool, moduleName)) 123 return tool; 124 } 125 } catch (ServiceConfigurationError e) { 126 throw new Error(e); 127 } 128 return null; 129 } 130 131 /** 132 * Determine if this is the desired tool instance. 133 * @param <T> the interface of the tool 134 * @param tool the instance of the tool 135 * @param moduleName the name of the module containing the desired implementation 136 * @return true if and only if the tool matches the specified criteria 137 */ matches(T tool, String moduleName)138 private static <T> boolean matches(T tool, String moduleName) { 139 PrivilegedAction<Boolean> pa = () -> { 140 Module toolModule = tool.getClass().getModule(); 141 String toolModuleName = toolModule.getName(); 142 return Objects.equals(toolModuleName, moduleName); 143 }; 144 return AccessController.doPrivileged(pa); 145 } 146 } 147