1 /*
   2  * Copyright (c) 1996, 2011, 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 java.lang.reflect;
  27 
  28 import sun.reflect.MethodAccessor;
  29 import sun.reflect.Reflection;
  30 import sun.reflect.generics.repository.MethodRepository;
  31 import sun.reflect.generics.factory.CoreReflectionFactory;
  32 import sun.reflect.generics.factory.GenericsFactory;
  33 import sun.reflect.generics.scope.MethodScope;
  34 import sun.reflect.annotation.AnnotationType;
  35 import sun.reflect.annotation.AnnotationParser;
  36 import java.lang.annotation.Annotation;
  37 import java.lang.annotation.AnnotationFormatError;
  38 import java.nio.ByteBuffer;
  39 
  40 /**
  41  * A {@code Method} provides information about, and access to, a single method
  42  * on a class or interface.  The reflected method may be a class method
  43  * or an instance method (including an abstract method).
  44  *
  45  * <p>A {@code Method} permits widening conversions to occur when matching the
  46  * actual parameters to invoke with the underlying method's formal
  47  * parameters, but it throws an {@code IllegalArgumentException} if a
  48  * narrowing conversion would occur.
  49  *
  50  * @see Member
  51  * @see java.lang.Class
  52  * @see java.lang.Class#getMethods()
  53  * @see java.lang.Class#getMethod(String, Class[])
  54  * @see java.lang.Class#getDeclaredMethods()
  55  * @see java.lang.Class#getDeclaredMethod(String, Class[])
  56  *
  57  * @author Kenneth Russell
  58  * @author Nakul Saraiya
  59  */
  60 public final class Method extends Executable {
  61     private Class<?>            clazz;
  62     private int                 slot;
  63     // This is guaranteed to be interned by the VM in the 1.4
  64     // reflection implementation
  65     private String              name;
  66     private Class<?>            returnType;
  67     private Class<?>[]          parameterTypes;
  68     private Class<?>[]          exceptionTypes;
  69     private int                 modifiers;
  70     // Generics and annotations support
  71     private transient String              signature;
  72     // generic info repository; lazily initialized
  73     private transient MethodRepository genericInfo;
  74     private byte[]              annotations;
  75     private byte[]              parameterAnnotations;
  76     private byte[]              annotationDefault;
  77     private volatile MethodAccessor methodAccessor;
  78     // For sharing of MethodAccessors. This branching structure is
  79     // currently only two levels deep (i.e., one root Method and
  80     // potentially many Method objects pointing to it.)
  81     private Method              root;
  82 
  83 
  84     // Generics infrastructure
  85     private String getGenericSignature() {return signature;}
  86 
  87     // Accessor for factory
  88     private GenericsFactory getFactory() {
  89         // create scope and factory
  90         return CoreReflectionFactory.make(this, MethodScope.make(this));
  91     }
  92 
  93     // Accessor for generic info repository
  94     @Override
  95     MethodRepository getGenericInfo() {
  96         // lazily initialize repository if necessary
  97         if (genericInfo == null) {
  98             // create and cache generic info repository
  99             genericInfo = MethodRepository.make(getGenericSignature(),
 100                                                 getFactory());
 101         }
 102         return genericInfo; //return cached repository
 103     }
 104 
 105     /**
 106      * Package-private constructor used by ReflectAccess to enable
 107      * instantiation of these objects in Java code from the java.lang
 108      * package via sun.reflect.LangReflectAccess.
 109      */
 110     Method(Class<?> declaringClass,
 111            String name,
 112            Class<?>[] parameterTypes,
 113            Class<?> returnType,
 114            Class<?>[] checkedExceptions,
 115            int modifiers,
 116            int slot,
 117            String signature,
 118            byte[] annotations,
 119            byte[] parameterAnnotations,
 120            byte[] annotationDefault) {
 121         this.clazz = declaringClass;
 122         this.name = name;
 123         this.parameterTypes = parameterTypes;
 124         this.returnType = returnType;
 125         this.exceptionTypes = checkedExceptions;
 126         this.modifiers = modifiers;
 127         this.slot = slot;
 128         this.signature = signature;
 129         this.annotations = annotations;
 130         this.parameterAnnotations = parameterAnnotations;
 131         this.annotationDefault = annotationDefault;
 132     }
 133 
 134     /**
 135      * Package-private routine (exposed to java.lang.Class via
 136      * ReflectAccess) which returns a copy of this Method. The copy's
 137      * "root" field points to this Method.
 138      */
 139     Method copy() {
 140         // This routine enables sharing of MethodAccessor objects
 141         // among Method objects which refer to the same underlying
 142         // method in the VM. (All of this contortion is only necessary
 143         // because of the "accessibility" bit in AccessibleObject,
 144         // which implicitly requires that new java.lang.reflect
 145         // objects be fabricated for each reflective call on Class
 146         // objects.)
 147         Method res = new Method(clazz, name, parameterTypes, returnType,
 148                                 exceptionTypes, modifiers, slot, signature,
 149                                 annotations, parameterAnnotations, annotationDefault);
 150         res.root = this;
 151         // Might as well eagerly propagate this if already present
 152         res.methodAccessor = methodAccessor;
 153         return res;
 154     }
 155 
 156     @Override
 157     boolean hasGenericInformation() {
 158         return (getGenericSignature() != null);
 159     }
 160 
 161     @Override
 162     byte[] getAnnotationBytes() {
 163         return annotations;
 164     }
 165 
 166     /**
 167      * {@inheritDoc}
 168      */
 169     @Override
 170     public Class<?> getDeclaringClass() {
 171         return clazz;
 172     }
 173 
 174     /**
 175      * Returns the name of the method represented by this {@code Method}
 176      * object, as a {@code String}.
 177      */
 178     @Override
 179     public String getName() {
 180         return name;
 181     }
 182 
 183     /**
 184      * {@inheritDoc}
 185      */
 186     @Override
 187     public int getModifiers() {
 188         return modifiers;
 189     }
 190 
 191     /**
 192      * {@inheritDoc}
 193      * @since 1.5
 194      */
 195     @Override
 196     public TypeVariable<Method>[] getTypeParameters() {
 197         if (getGenericSignature() != null)
 198             return (TypeVariable<Method>[])getGenericInfo().getTypeParameters();
 199         else
 200             return (TypeVariable<Method>[])new TypeVariable[0];
 201     }
 202 
 203     /**
 204      * Returns a {@code Class} object that represents the formal return type
 205      * of the method represented by this {@code Method} object.
 206      *
 207      * @return the return type for the method this object represents
 208      */
 209     public Class<?> getReturnType() {
 210         return returnType;
 211     }
 212 
 213     /**
 214      * Returns a {@code Type} object that represents the formal return
 215      * type of the method represented by this {@code Method} object.
 216      *
 217      * <p>If the return type is a parameterized type,
 218      * the {@code Type} object returned must accurately reflect
 219      * the actual type parameters used in the source code.
 220      *
 221      * <p>If the return type is a type variable or a parameterized type, it
 222      * is created. Otherwise, it is resolved.
 223      *
 224      * @return  a {@code Type} object that represents the formal return
 225      *     type of the underlying  method
 226      * @throws GenericSignatureFormatError
 227      *     if the generic method signature does not conform to the format
 228      *     specified in
 229      *     <cite>The Java&trade; Virtual Machine Specification</cite>
 230      * @throws TypeNotPresentException if the underlying method's
 231      *     return type refers to a non-existent type declaration
 232      * @throws MalformedParameterizedTypeException if the
 233      *     underlying method's return typed refers to a parameterized
 234      *     type that cannot be instantiated for any reason
 235      * @since 1.5
 236      */
 237     public Type getGenericReturnType() {
 238       if (getGenericSignature() != null) {
 239         return getGenericInfo().getReturnType();
 240       } else { return getReturnType();}
 241     }
 242 
 243     /**
 244      * {@inheritDoc}
 245      */
 246     @Override
 247     public Class<?>[] getParameterTypes() {
 248         return (Class<?>[]) parameterTypes.clone();
 249     }
 250 
 251     /**
 252      * {@inheritDoc}
 253      * @since 1.5
 254      */
 255     @Override
 256     public Type[] getGenericParameterTypes() {
 257         return super.getGenericParameterTypes();
 258     }
 259 
 260     /**
 261      * {@inheritDoc}
 262      * @since 1.5
 263      */
 264     @Override
 265     public Class<?>[] getExceptionTypes() {
 266         return (Class<?>[]) exceptionTypes.clone();
 267     }
 268 
 269     /**
 270      * {@inheritDoc}
 271      * @since 1.5
 272      */
 273     @Override
 274     public Type[] getGenericExceptionTypes() {
 275         return super.getGenericExceptionTypes();
 276     }
 277 
 278     /**
 279      * Compares this {@code Method} against the specified object.  Returns
 280      * true if the objects are the same.  Two {@code Methods} are the same if
 281      * they were declared by the same class and have the same name
 282      * and formal parameter types and return type.
 283      */
 284     public boolean equals(Object obj) {
 285         if (obj != null && obj instanceof Method) {
 286             Method other = (Method)obj;
 287             if ((getDeclaringClass() == other.getDeclaringClass())
 288                 && (getName() == other.getName())) {
 289                 if (!returnType.equals(other.getReturnType()))
 290                     return false;
 291                 return equalParamTypes(parameterTypes, other.parameterTypes);
 292             }
 293         }
 294         return false;
 295     }
 296 
 297     /**
 298      * Returns a hashcode for this {@code Method}.  The hashcode is computed
 299      * as the exclusive-or of the hashcodes for the underlying
 300      * method's declaring class name and the method's name.
 301      */
 302     public int hashCode() {
 303         return getDeclaringClass().getName().hashCode() ^ getName().hashCode();
 304     }
 305 
 306     /**
 307      * Returns a string describing this {@code Method}.  The string is
 308      * formatted as the method access modifiers, if any, followed by
 309      * the method return type, followed by a space, followed by the
 310      * class declaring the method, followed by a period, followed by
 311      * the method name, followed by a parenthesized, comma-separated
 312      * list of the method's formal parameter types. If the method
 313      * throws checked exceptions, the parameter list is followed by a
 314      * space, followed by the word throws followed by a
 315      * comma-separated list of the thrown exception types.
 316      * For example:
 317      * <pre>
 318      *    public boolean java.lang.Object.equals(java.lang.Object)
 319      * </pre>
 320      *
 321      * <p>The access modifiers are placed in canonical order as
 322      * specified by "The Java Language Specification".  This is
 323      * {@code public}, {@code protected} or {@code private} first,
 324      * and then other modifiers in the following order:
 325      * {@code abstract}, {@code static}, {@code final},
 326      * {@code synchronized}, {@code native}, {@code strictfp}.
 327      */
 328     public String toString() {
 329         return sharedToString(Modifier.methodModifiers(),
 330                               parameterTypes,
 331                               exceptionTypes);
 332     }
 333 
 334     @Override
 335     void specificToStringHeader(StringBuilder sb) {
 336         sb.append(Field.getTypeName(getReturnType())).append(' ');
 337         sb.append(Field.getTypeName(getDeclaringClass())).append('.');
 338         sb.append(getName());
 339     }
 340 
 341     /**
 342      * Returns a string describing this {@code Method}, including
 343      * type parameters.  The string is formatted as the method access
 344      * modifiers, if any, followed by an angle-bracketed
 345      * comma-separated list of the method's type parameters, if any,
 346      * followed by the method's generic return type, followed by a
 347      * space, followed by the class declaring the method, followed by
 348      * a period, followed by the method name, followed by a
 349      * parenthesized, comma-separated list of the method's generic
 350      * formal parameter types.
 351      *
 352      * If this method was declared to take a variable number of
 353      * arguments, instead of denoting the last parameter as
 354      * "<tt><i>Type</i>[]</tt>", it is denoted as
 355      * "<tt><i>Type</i>...</tt>".
 356      *
 357      * A space is used to separate access modifiers from one another
 358      * and from the type parameters or return type.  If there are no
 359      * type parameters, the type parameter list is elided; if the type
 360      * parameter list is present, a space separates the list from the
 361      * class name.  If the method is declared to throw exceptions, the
 362      * parameter list is followed by a space, followed by the word
 363      * throws followed by a comma-separated list of the generic thrown
 364      * exception types.  If there are no type parameters, the type
 365      * parameter list is elided.
 366      *
 367      * <p>The access modifiers are placed in canonical order as
 368      * specified by "The Java Language Specification".  This is
 369      * {@code public}, {@code protected} or {@code private} first,
 370      * and then other modifiers in the following order:
 371      * {@code abstract}, {@code static}, {@code final},
 372      * {@code synchronized}, {@code native}, {@code strictfp}.
 373      *
 374      * @return a string describing this {@code Method},
 375      * include type parameters
 376      *
 377      * @since 1.5
 378      */
 379     @Override
 380     public String toGenericString() {
 381         return sharedToGenericString(Modifier.methodModifiers());
 382     }
 383 
 384     @Override
 385     void specificToGenericStringHeader(StringBuilder sb) {
 386         Type genRetType = getGenericReturnType();
 387         sb.append( ((genRetType instanceof Class<?>)?
 388                     Field.getTypeName((Class<?>)genRetType):genRetType.toString()))
 389             .append(' ');
 390 
 391         sb.append(Field.getTypeName(getDeclaringClass())).append('.');
 392         sb.append(getName());
 393     }
 394 
 395     /**
 396      * Invokes the underlying method represented by this {@code Method}
 397      * object, on the specified object with the specified parameters.
 398      * Individual parameters are automatically unwrapped to match
 399      * primitive formal parameters, and both primitive and reference
 400      * parameters are subject to method invocation conversions as
 401      * necessary.
 402      *
 403      * <p>If the underlying method is static, then the specified {@code obj}
 404      * argument is ignored. It may be null.
 405      *
 406      * <p>If the number of formal parameters required by the underlying method is
 407      * 0, the supplied {@code args} array may be of length 0 or null.
 408      *
 409      * <p>If the underlying method is an instance method, it is invoked
 410      * using dynamic method lookup as documented in The Java Language
 411      * Specification, Second Edition, section 15.12.4.4; in particular,
 412      * overriding based on the runtime type of the target object will occur.
 413      *
 414      * <p>If the underlying method is static, the class that declared
 415      * the method is initialized if it has not already been initialized.
 416      *
 417      * <p>If the method completes normally, the value it returns is
 418      * returned to the caller of invoke; if the value has a primitive
 419      * type, it is first appropriately wrapped in an object. However,
 420      * if the value has the type of an array of a primitive type, the
 421      * elements of the array are <i>not</i> wrapped in objects; in
 422      * other words, an array of primitive type is returned.  If the
 423      * underlying method return type is void, the invocation returns
 424      * null.
 425      *
 426      * @param obj  the object the underlying method is invoked from
 427      * @param args the arguments used for the method call
 428      * @return the result of dispatching the method represented by
 429      * this object on {@code obj} with parameters
 430      * {@code args}
 431      *
 432      * @exception IllegalAccessException    if this {@code Method} object
 433      *              is enforcing Java language access control and the underlying
 434      *              method is inaccessible.
 435      * @exception IllegalArgumentException  if the method is an
 436      *              instance method and the specified object argument
 437      *              is not an instance of the class or interface
 438      *              declaring the underlying method (or of a subclass
 439      *              or implementor thereof); if the number of actual
 440      *              and formal parameters differ; if an unwrapping
 441      *              conversion for primitive arguments fails; or if,
 442      *              after possible unwrapping, a parameter value
 443      *              cannot be converted to the corresponding formal
 444      *              parameter type by a method invocation conversion.
 445      * @exception InvocationTargetException if the underlying method
 446      *              throws an exception.
 447      * @exception NullPointerException      if the specified object is null
 448      *              and the method is an instance method.
 449      * @exception ExceptionInInitializerError if the initialization
 450      * provoked by this method fails.
 451      */
 452     public Object invoke(Object obj, Object... args)
 453         throws IllegalAccessException, IllegalArgumentException,
 454            InvocationTargetException
 455     {
 456         if (!override) {
 457             if (!Reflection.quickCheckMemberAccess(clazz, modifiers)) {
 458                 Class<?> caller = Reflection.getCallerClass(1);
 459 
 460                 checkAccess(caller, clazz, obj, modifiers);
 461             }
 462         }
 463         MethodAccessor ma = methodAccessor;             // read volatile
 464         if (ma == null) {
 465             ma = acquireMethodAccessor();
 466         }
 467         return ma.invoke(obj, args);
 468     }
 469 
 470     /**
 471      * Returns {@code true} if this method is a bridge
 472      * method; returns {@code false} otherwise.
 473      *
 474      * @return true if and only if this method is a bridge
 475      * method as defined by the Java Language Specification.
 476      * @since 1.5
 477      */
 478     public boolean isBridge() {
 479         return (getModifiers() & Modifier.BRIDGE) != 0;
 480     }
 481 
 482     /**
 483      * {@inheritDoc}
 484      * @since 1.5
 485      */
 486     @Override
 487     public boolean isVarArgs() {
 488         return super.isVarArgs();
 489     }
 490 
 491     /**
 492      * {@inheritDoc}
 493      * @since 1.5
 494      */
 495     @Override
 496     public boolean isSynthetic() {
 497         return super.isSynthetic();
 498     }
 499 
 500     // NOTE that there is no synchronization used here. It is correct
 501     // (though not efficient) to generate more than one MethodAccessor
 502     // for a given Method. However, avoiding synchronization will
 503     // probably make the implementation more scalable.
 504     private MethodAccessor acquireMethodAccessor() {
 505         // First check to see if one has been created yet, and take it
 506         // if so
 507         MethodAccessor tmp = null;
 508         if (root != null) tmp = root.getMethodAccessor();
 509         if (tmp != null) {
 510             methodAccessor = tmp;
 511         } else {
 512             // Otherwise fabricate one and propagate it up to the root
 513             tmp = reflectionFactory.newMethodAccessor(this);
 514             setMethodAccessor(tmp);
 515         }
 516 
 517         return tmp;
 518     }
 519 
 520     // Returns MethodAccessor for this Method object, not looking up
 521     // the chain to the root
 522     MethodAccessor getMethodAccessor() {
 523         return methodAccessor;
 524     }
 525 
 526     // Sets the MethodAccessor for this Method object and
 527     // (recursively) its root
 528     void setMethodAccessor(MethodAccessor accessor) {
 529         methodAccessor = accessor;
 530         // Propagate up
 531         if (root != null) {
 532             root.setMethodAccessor(accessor);
 533         }
 534     }
 535 
 536     /**
 537      * Returns the default value for the annotation member represented by
 538      * this {@code Method} instance.  If the member is of a primitive type,
 539      * an instance of the corresponding wrapper type is returned. Returns
 540      * null if no default is associated with the member, or if the method
 541      * instance does not represent a declared member of an annotation type.
 542      *
 543      * @return the default value for the annotation member represented
 544      *     by this {@code Method} instance.
 545      * @throws TypeNotPresentException if the annotation is of type
 546      *     {@link Class} and no definition can be found for the
 547      *     default class value.
 548      * @since  1.5
 549      */
 550     public Object getDefaultValue() {
 551         if  (annotationDefault == null)
 552             return null;
 553         Class<?> memberType = AnnotationType.invocationHandlerReturnType(
 554             getReturnType());
 555         Object result = AnnotationParser.parseMemberValue(
 556             memberType, ByteBuffer.wrap(annotationDefault),
 557             sun.misc.SharedSecrets.getJavaLangAccess().
 558                 getConstantPool(getDeclaringClass()),
 559             getDeclaringClass());
 560         if (result instanceof sun.reflect.annotation.ExceptionProxy)
 561             throw new AnnotationFormatError("Invalid default: " + this);
 562         return result;
 563     }
 564 
 565     /**
 566      * {@inheritDoc}
 567      * @since 1.5
 568      */
 569     @Override
 570     public Annotation[][] getParameterAnnotations() {
 571         return sharedGetParameterAnnotations(parameterTypes, parameterAnnotations);
 572     }
 573 
 574     @Override
 575     void handleParameterNumberMismatch(int resultLength, int numParameters) {
 576         throw new AnnotationFormatError("Parameter annotations don't match number of parameters");
 577     }
 578 }