1/* 2 * Copyright (c) 2016, 2017, 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. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23package org.graalvm.compiler.core.common.util; 24 25import static org.graalvm.compiler.core.common.util.Util.JAVA_SPECIFICATION_VERSION; 26 27import java.lang.reflect.InvocationTargetException; 28import java.lang.reflect.Method; 29import java.lang.reflect.Modifier; 30 31/** 32 * Reflection based access to the Module API introduced by JDK 9. This allows the API to be used in 33 * code that must be compiled on a JDK prior to 9. Use of this class must be guarded by a test for 34 * JDK 9 or later. For example: 35 * 36 * <pre> 37 * if (Util.JAVA_SPECIFICATION_VERSION >= 9) { 38 * // Use of ModuleAPI 39 * } 40 * </pre> 41 */ 42public final class ModuleAPI { 43 44 private ModuleAPI(Method method) { 45 this.method = method; 46 } 47 48 private final Method method; 49 50 /** 51 * {@code Class.getModule()}. 52 */ 53 public static final ModuleAPI getModule; 54 55 /** 56 * {@code java.lang.Module.getResourceAsStream(String)}. 57 */ 58 public static final ModuleAPI getResourceAsStream; 59 60 /** 61 * {@code java.lang.Module.canRead(Module)}. 62 */ 63 public static final ModuleAPI canRead; 64 65 /** 66 * {@code java.lang.Module.isExported(String)}. 67 */ 68 public static final ModuleAPI isExported; 69 70 /** 71 * {@code java.lang.Module.isExported(String, Module)}. 72 */ 73 public static final ModuleAPI isExportedTo; 74 75 /** 76 * Invokes the static Module API method represented by this object. 77 */ 78 @SuppressWarnings("unchecked") 79 public <T> T invokeStatic(Object... args) { 80 checkAvailability(); 81 assert Modifier.isStatic(method.getModifiers()); 82 try { 83 return (T) method.invoke(null, args); 84 } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e) { 85 throw new InternalError(e); 86 } 87 } 88 89 /** 90 * Invokes the non-static Module API method represented by this object. 91 */ 92 @SuppressWarnings("unchecked") 93 public <T> T invoke(Object receiver, Object... args) { 94 checkAvailability(); 95 assert !Modifier.isStatic(method.getModifiers()); 96 try { 97 return (T) method.invoke(receiver, args); 98 } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e) { 99 throw new InternalError(e); 100 } 101 } 102 103 private void checkAvailability() throws InternalError { 104 if (method == null) { 105 throw new InternalError("Cannot use Module API on JDK " + JAVA_SPECIFICATION_VERSION); 106 } 107 } 108 109 static { 110 if (JAVA_SPECIFICATION_VERSION >= 9) { 111 try { 112 getModule = new ModuleAPI(Class.class.getMethod("getModule")); 113 Class<?> moduleClass = getModule.method.getReturnType(); 114 getResourceAsStream = new ModuleAPI(moduleClass.getMethod("getResourceAsStream", String.class)); 115 canRead = new ModuleAPI(moduleClass.getMethod("canRead", moduleClass)); 116 isExported = new ModuleAPI(moduleClass.getMethod("isExported", String.class)); 117 isExportedTo = new ModuleAPI(moduleClass.getMethod("isExported", String.class, moduleClass)); 118 } catch (NoSuchMethodException | SecurityException e) { 119 throw new InternalError(e); 120 } 121 } else { 122 ModuleAPI unavailable = new ModuleAPI(null); 123 getModule = unavailable; 124 getResourceAsStream = unavailable; 125 canRead = unavailable; 126 isExported = unavailable; 127 isExportedTo = unavailable; 128 } 129 } 130} 131