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| 1 | /* | ||
| 2 | * Copyright (c) 2003, 2006, 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 | package com.sun.beans; | ||
| 26 | |||
| 27 | import java.lang.reflect.Array; | ||
| 28 | import java.lang.reflect.GenericArrayType; | ||
| 29 | import java.lang.reflect.ParameterizedType; | ||
| 30 | import java.lang.reflect.Type; | ||
| 31 | import java.lang.reflect.TypeVariable; | ||
| 32 | import java.lang.reflect.WildcardType; | ||
| 33 | import java.util.HashMap; | ||
| 34 | import java.util.Map; | ||
| 35 | |||
| 36 | import sun.reflect.generics.reflectiveObjects.GenericArrayTypeImpl; | ||
| 37 | import sun.reflect.generics.reflectiveObjects.ParameterizedTypeImpl; | ||
| 38 | |||
| 39 | /** | ||
| 40 | * This is utility class to resolve types. | ||
| 41 | * | ||
| 42 | * @since 1.7 | ||
| 43 | * | ||
| 44 | * @author Eamonn McManus | ||
| 45 | * @author Sergey Malenkov | ||
| 46 | */ | ||
| 47 | public final class TypeResolver { | ||
| 48 | /** | ||
| 49 | * Replaces the given {@code type} in an inherited method | ||
| 50 | * with the actual type it has in the given {@code inClass}. | ||
| 51 | * | ||
| 52 | * <p>Although type parameters are not inherited by subclasses in the Java | ||
| 53 | * language, they <em>are</em> effectively inherited when using reflection. | ||
| 54 | * For example, if you declare an interface like this...</p> | ||
| 55 | * | ||
| 56 | * <pre> | ||
| 57 | * public interface StringToIntMap extends Map<String,Integer> {} | ||
| 58 | * </pre> | ||
| 59 | * | ||
| 60 | * <p>...then StringToIntMap.class.getMethods() will show that it has methods | ||
| 61 | * like put(K,V) even though StringToIntMap has no type parameters. The K | ||
| 62 | * and V variables are the ones declared by Map, so | ||
| 63 | * {@link TypeVariable#getGenericDeclaration()} will return Map.class.</p> | ||
| 64 | * | ||
| 65 | * <p>The purpose of this method is to take a Type from a possibly-inherited | ||
| 66 | * method and replace it with the correct Type for the inheriting class. | ||
| 67 | * So given parameters of K and StringToIntMap.class in the above example, | ||
| 68 | * this method will return String.</p> | ||
| 69 | * | ||
| 70 | * @param inClass the base class used to resolve | ||
| 71 | * @param type the type to resolve | ||
| 72 | * @return a resolved type | ||
| 73 | * | ||
| 74 | * @see #getActualType(Class) | ||
| 75 | * @see #resolve(Type,Type) | ||
| 76 | */ | ||
| 77 | public static Type resolveInClass(Class<?> inClass, Type type) { | ||
| 78 | return resolve(getActualType(inClass), type); | ||
| 79 | } | ||
| 80 | |||
| 81 | /** | ||
| 82 | * Replaces all {@code types} in the given array | ||
| 83 | * with the actual types they have in the given {@code inClass}. | ||
| 84 | * | ||
| 85 | * @param inClass the base class used to resolve | ||
| 86 | * @param types the array of types to resolve | ||
| 87 | * @return an array of resolved types | ||
| 88 | * | ||
| 89 | * @see #getActualType(Class) | ||
| 90 | * @see #resolve(Type,Type[]) | ||
| 91 | */ | ||
| 92 | public static Type[] resolveInClass(Class<?> inClass, Type[] types) { | ||
| 93 | return resolve(getActualType(inClass), types); | ||
| 94 | } | ||
| 95 | |||
| 96 | /** | ||
| 97 | * Replaces type variables of the given {@code formal} type | ||
| 98 | * with the types they stand for in the given {@code actual} type. | ||
| 99 | * | ||
| 100 | * <p>A ParameterizedType is a class with type parameters, and the values | ||
| 101 | * of those parameters. For example, Map<K,V> is a generic class, and | ||
| 102 | * a corresponding ParameterizedType might look like | ||
| 103 | * Map<K=String,V=Integer>. Given such a ParameterizedType, this method | ||
| 104 | * will replace K with String, or List<K> with List<String;, or | ||
| 105 | * List<? super K> with List<? super String>.</p> | ||
| 106 | * | ||
| 107 | * <p>The {@code actual} argument to this method can also be a Class. | ||
| 108 | * In this case, either it is equivalent to a ParameterizedType with | ||
| 109 | * no parameters (for example, Integer.class), or it is equivalent to | ||
| 110 | * a "raw" ParameterizedType (for example, Map.class). In the latter | ||
| 111 | * case, every type parameter declared or inherited by the class is replaced | ||
| 112 | * by its "erasure". For a type parameter declared as <T>, the erasure | ||
| 113 | * is Object. For a type parameter declared as <T extends Number>, | ||
| 114 | * the erasure is Number.</p> | ||
| 115 | * | ||
| 116 | * <p>Although type parameters are not inherited by subclasses in the Java | ||
| 117 | * language, they <em>are</em> effectively inherited when using reflection. | ||
| 118 | * For example, if you declare an interface like this...</p> | ||
| 119 | * | ||
| 120 | * <pre> | ||
| 121 | * public interface StringToIntMap extends Map<String,Integer> {} | ||
| 122 | * </pre> | ||
| 123 | * | ||
| 124 | * <p>...then StringToIntMap.class.getMethods() will show that it has methods | ||
| 125 | * like put(K,V) even though StringToIntMap has no type parameters. The K | ||
| 126 | * and V variables are the ones declared by Map, so | ||
| 127 | * {@link TypeVariable#getGenericDeclaration()} will return {@link Map Map.class}.</p> | ||
| 128 | * | ||
| 129 | * <p>For this reason, this method replaces inherited type parameters too. | ||
| 130 | * Therefore if this method is called with {@code actual} being | ||
| 131 | * StringToIntMap.class and {@code formal} being the K from Map, | ||
| 132 | * it will return {@link String String.class}.</p> | ||
| 133 | * | ||
| 134 | * <p>In the case where {@code actual} is a "raw" ParameterizedType, the | ||
| 135 | * inherited type parameters will also be replaced by their erasures. | ||
| 136 | * The erasure of a Class is the Class itself, so a "raw" subinterface of | ||
| 137 | * StringToIntMap will still show the K from Map as String.class. But | ||
| 138 | * in a case like this... | ||
| 139 | * | ||
| 140 | * <pre> | ||
| 141 | * public interface StringToIntListMap extends Map<String,List<Integer>> {} | ||
| 142 | * public interface RawStringToIntListMap extends StringToIntListMap {} | ||
| 143 | * </pre> | ||
| 144 | * | ||
| 145 | * <p>...the V inherited from Map will show up as List<Integer> in | ||
| 146 | * StringToIntListMap, but as plain List in RawStringToIntListMap.</p> | ||
| 147 | * | ||
| 148 | * @param actual the type that supplies bindings for type variables | ||
| 149 | * @param formal the type where occurrences of the variables | ||
| 150 | * in {@code actual} will be replaced by the corresponding bound values | ||
| 151 | * @return a resolved type | ||
| 152 | * | ||
| 153 | * @see #TypeResolver(Type) | ||
| 154 | * @see #resolve(Type) | ||
| 155 | */ | ||
| 156 | public static Type resolve(Type actual, Type formal) { | ||
| 157 | return new TypeResolver(actual).resolve(formal); | ||
| 158 | } | ||
| 159 | |||
| 160 | /** | ||
| 161 | * Replaces type variables of all formal types in the given array | ||
| 162 | * with the types they stand for in the given {@code actual} type. | ||
| 163 | * | ||
| 164 | * @param actual the type that supplies bindings for type variables | ||
| 165 | * @param formals the array of types to resolve | ||
| 166 | * @return an array of resolved types | ||
| 167 | * | ||
| 168 | * @see #TypeResolver(Type) | ||
| 169 | * @see #resolve(Type[]) | ||
| 170 | */ | ||
| 171 | public static Type[] resolve(Type actual, Type[] formals) { | ||
| 172 | return new TypeResolver(actual).resolve(formals); | ||
| 173 | } | ||
| 174 | |||
| 175 | /** | ||
| 176 | * Converts the given {@code type} to the corresponding class. | ||
| 177 | * This method implements the concept of type erasure, | ||
| 178 | * that is described in section 4.6 of | ||
| 179 | * <cite>The Java™ Language Specification</cite>. | ||
| 180 | * | ||
| 181 | * @param type the array of types to convert | ||
| 182 | * @return a corresponding class | ||
| 183 | */ | ||
| 184 | public static Class<?> erase(Type type) { | ||
| 185 | if (type instanceof Class) { | ||
| 186 | return (Class<?>) type; | ||
| 187 | } | ||
| 188 | if (type instanceof ParameterizedType) { | ||
| 189 | ParameterizedType pt = (ParameterizedType) type; | ||
| 190 | return (Class<?>) pt.getRawType(); | ||
| 191 | } | ||
| 192 | if (type instanceof TypeVariable) { | ||
| 193 | TypeVariable tv = (TypeVariable)type; | ||
| 194 | Type[] bounds = tv.getBounds(); | ||
| 195 | return (0 < bounds.length) | ||
| 196 | ? erase(bounds[0]) | ||
| 197 | : Object.class; | ||
| 198 | } | ||
| 199 | if (type instanceof WildcardType) { | ||
| 200 | WildcardType wt = (WildcardType)type; | ||
| 201 | Type[] bounds = wt.getUpperBounds(); | ||
| 202 | return (0 < bounds.length) | ||
| 203 | ? erase(bounds[0]) | ||
| 204 | : Object.class; | ||
| 205 | } | ||
| 206 | if (type instanceof GenericArrayType) { | ||
| 207 | GenericArrayType gat = (GenericArrayType)type; | ||
| 208 | return Array.newInstance(erase(gat.getGenericComponentType()), 0).getClass(); | ||
| 209 | } | ||
| 210 | throw new IllegalArgumentException("Unknown Type kind: " + type.getClass()); | ||
| 211 | } | ||
| 212 | |||
| 213 | /** | ||
| 214 | * Converts all {@code types} in the given array | ||
| 215 | * to the corresponding classes. | ||
| 216 | * | ||
| 217 | * @param types the array of types to convert | ||
| 218 | * @return an array of corresponding classes | ||
| 219 | * | ||
| 220 | * @see #erase(Type) | ||
| 221 | */ | ||
| 222 | public static Class[] erase(Type[] types) { | ||
| 223 | int length = types.length; | ||
| 224 | Class[] classes = new Class[length]; | ||
| 225 | for (int i = 0; i < length; i++) { | ||
| 226 | classes[i] = TypeResolver.erase(types[i]); | ||
| 227 | } | ||
| 228 | return classes; | ||
| 229 | } | ||
| 230 | |||
| 231 | |||
| 232 | private final Map<TypeVariable<?>, Type> map | ||
| 233 | = new HashMap<TypeVariable<?>, Type>(); | ||
| 234 | |||
| 235 | /** | ||
| 236 | * Constructs the type resolver for the given actual type. | ||
| 237 | * | ||
| 238 | * @param actual the type that supplies bindings for type variables | ||
| 239 | * | ||
| 240 | * @see #prepare(Type) | ||
| 241 | */ | ||
| 242 | private TypeResolver(Type actual) { | ||
| 243 | prepare(actual); | ||
| 244 | } | ||
| 245 | |||
| 246 | /** | ||
| 247 | * Fills the map from type parameters | ||
| 248 | * to types as seen by the given {@code type}. | ||
| 249 | * The method is recursive because the {@code type} | ||
| 250 | * inherits mappings from its parent classes and interfaces. | ||
| 251 | * The {@code type} can be either a {@link Class Class} | ||
| 252 | * or a {@link ParameterizedType ParameterizedType}. | ||
| 253 | * If it is a {@link Class Class}, it is either equivalent | ||
| 254 | * to a {@link ParameterizedType ParameterizedType} with no parameters, | ||
| 255 | * or it represents the erasure of a {@link ParameterizedType ParameterizedType}. | ||
| 256 | * | ||
| 257 | * @param type the next type in the hierarchy | ||
| 258 | */ | ||
| 259 | private void prepare(Type type) { | ||
| 260 | Class<?> raw = (Class<?>)((type instanceof Class<?>) | ||
| 261 | ? type | ||
| 262 | : ((ParameterizedType)type).getRawType()); | ||
| 263 | |||
| 264 | TypeVariable<?>[] formals = raw.getTypeParameters(); | ||
| 265 | |||
| 266 | Type[] actuals = (type instanceof Class<?>) | ||
| 267 | ? formals | ||
| 268 | : ((ParameterizedType)type).getActualTypeArguments(); | ||
| 269 | |||
| 270 | assert formals.length == actuals.length; | ||
| 271 | for (int i = 0; i < formals.length; i++) { | ||
| 272 | this.map.put(formals[i], actuals[i]); | ||
| 273 | } | ||
| 274 | Type gSuperclass = raw.getGenericSuperclass(); | ||
| 275 | if (gSuperclass != null) { | ||
| 276 | prepare(gSuperclass); | ||
| 277 | } | ||
| 278 | for (Type gInterface : raw.getGenericInterfaces()) { | ||
| 279 | prepare(gInterface); | ||
| 280 | } | ||
| 281 | // If type is the raw version of a parameterized class, we type-erase | ||
| 282 | // all of its type variables, including inherited ones. | ||
| 283 | if (type instanceof Class<?> && formals.length > 0) { | ||
| 284 | for (Map.Entry<TypeVariable<?>, Type> entry : this.map.entrySet()) { | ||
| 285 | entry.setValue(erase(entry.getValue())); | ||
| 286 | } | ||
| 287 | } | ||
| 288 | } | ||
| 289 | |||
| 290 | /** | ||
| 291 | * Replaces the given {@code formal} type | ||
| 292 | * with the type it stand for in this type resolver. | ||
| 293 | * | ||
| 294 | * @param formal the array of types to resolve | ||
| 295 | * @return a resolved type | ||
| 296 | */ | ||
| 297 | private Type resolve(Type formal) { | ||
| 298 | if (formal instanceof Class) { | ||
| 299 | return formal; | ||
| 300 | } | ||
| 301 | if (formal instanceof GenericArrayType) { | ||
| 302 | Type comp = ((GenericArrayType)formal).getGenericComponentType(); | ||
| 303 | comp = resolve(comp); | ||
| 304 | return (comp instanceof Class) | ||
| 305 | ? Array.newInstance((Class<?>)comp, 0).getClass() | ||
| 306 | : GenericArrayTypeImpl.make(comp); | ||
| 307 | } | ||
| 308 | if (formal instanceof ParameterizedType) { | ||
| 309 | ParameterizedType fpt = (ParameterizedType)formal; | ||
| 310 | Type[] actuals = resolve(fpt.getActualTypeArguments()); | ||
| 311 | return ParameterizedTypeImpl.make( | ||
| 312 | (Class<?>)fpt.getRawType(), actuals, fpt.getOwnerType()); | ||
| 313 | } | ||
| 314 | if (formal instanceof WildcardType) { | ||
| 315 | WildcardType fwt = (WildcardType)formal; | ||
| 316 | Type[] upper = resolve(fwt.getUpperBounds()); | ||
| 317 | Type[] lower = resolve(fwt.getLowerBounds()); | ||
| 318 | return new WildcardTypeImpl(upper, lower); | ||
| 319 | } | ||
| 320 | if (!(formal instanceof TypeVariable)) { | ||
| 321 | throw new IllegalArgumentException("Bad Type kind: " + formal.getClass()); | ||
| 322 | } | ||
| 323 | Type actual = this.map.get((TypeVariable) formal); | ||
| 324 | if (actual == null || actual.equals(formal)) { | ||
| 325 | return formal; | ||
| 326 | } | ||
| 327 | actual = fixGenericArray(actual); | ||
| 328 | return resolve(actual); | ||
| 329 | // A variable can be bound to another variable that is itself bound | ||
| 330 | // to something. For example, given: | ||
| 331 | // class Super<T> {...} | ||
| 332 | // class Mid<X> extends Super<T> {...} | ||
| 333 | // class Sub extends Mid<String> | ||
| 334 | // the variable T is bound to X, which is in turn bound to String. | ||
| 335 | // So if we have to resolve T, we need the tail recursion here. | ||
| 336 | } | ||
| 337 | |||
| 338 | /** | ||
| 339 | * Replaces all formal types in the given array | ||
| 340 | * with the types they stand for in this type resolver. | ||
| 341 | * | ||
| 342 | * @param formals the array of types to resolve | ||
| 343 | * @return an array of resolved types | ||
| 344 | * | ||
| 345 | * @see #resolve(Type) | ||
| 346 | */ | ||
| 347 | private Type[] resolve(Type[] formals) { | ||
| 348 | int length = formals.length; | ||
| 349 | Type[] actuals = new Type[length]; | ||
| 350 | for (int i = 0; i < length; i++) { | ||
| 351 | actuals[i] = resolve(formals[i]); | ||
| 352 | } | ||
| 353 | return actuals; | ||
| 354 | } | ||
| 355 | |||
| 356 | /** | ||
| 357 | * Replaces a {@link GenericArrayType GenericArrayType} | ||
| 358 | * with plain array class where it is possible. | ||
| 359 | * Bug <a href="http://bugs.sun.com/view_bug.do?bug_id=5041784">5041784</a> | ||
| 360 | * is that arrays of non-generic type sometimes show up | ||
| 361 | * as {@link GenericArrayType GenericArrayType} when using reflection. | ||
| 362 | * For example, a {@code String[]} might show up | ||
| 363 | * as a {@link GenericArrayType GenericArrayType} | ||
| 364 | * where {@link GenericArrayType#getGenericComponentType getGenericComponentType} | ||
| 365 | * is {@code String.class}. This violates the specification, | ||
| 366 | * which says that {@link GenericArrayType GenericArrayType} | ||
| 367 | * is used when the component type is a type variable or parameterized type. | ||
| 368 | * We fit the specification here. | ||
| 369 | * | ||
| 370 | * @param type the type to fix | ||
| 371 | * @return a corresponding type for the generic array type, | ||
| 372 | * or the same type as {@code type} | ||
| 373 | */ | ||
| 374 | private static Type fixGenericArray(Type type) { | ||
| 375 | if (type instanceof GenericArrayType) { | ||
| 376 | Type comp = ((GenericArrayType)type).getGenericComponentType(); | ||
| 377 | comp = fixGenericArray(comp); | ||
| 378 | if (comp instanceof Class) { | ||
| 379 | return Array.newInstance((Class<?>)comp, 0).getClass(); | ||
| 380 | } | ||
| 381 | } | ||
| 382 | return type; | ||
| 383 | } | ||
| 384 | |||
| 385 | /** | ||
| 386 | * Replaces a {@link Class Class} with type parameters | ||
| 387 | * with a {@link ParameterizedType ParameterizedType} | ||
| 388 | * where every parameter is bound to itself. | ||
| 389 | * When calling {@link #resolveInClass} in the context of {@code inClass}, | ||
| 390 | * we can't just pass {@code inClass} as the {@code actual} parameter, | ||
| 391 | * because if {@code inClass} has type parameters | ||
| 392 | * that would be interpreted as accessing the raw type, | ||
| 393 | * so we would get unwanted erasure. | ||
| 394 | * This is why we bind each parameter to itself. | ||
| 395 | * If {@code inClass} does have type parameters and has methods | ||
| 396 | * where those parameters appear in the return type or argument types, | ||
| 397 | * we will correctly leave those types alone. | ||
| 398 | * | ||
| 399 | * @param inClass the base class used to resolve | ||
| 400 | * @return a parameterized type for the class, | ||
| 401 | * or the same class as {@code inClass} | ||
| 402 | */ | ||
| 403 | private static Type getActualType(Class<?> inClass) { | ||
| 404 | Type[] params = inClass.getTypeParameters(); | ||
| 405 | return (params.length == 0) | ||
| 406 | ? inClass | ||
| 407 | : ParameterizedTypeImpl.make( | ||
| 408 | inClass, params, inClass.getEnclosingClass()); | ||
| 409 | } | ||
| 410 | } | ||