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      * @throws GenericSignatureFormatError {@inheritDoc}
 194      * @since 1.5
 195      */
 196     @Override
 197     @SuppressWarnings({"rawtypes", "unchecked"})
 198     public TypeVariable<Method>[] getTypeParameters() {
 199         if (getGenericSignature() != null)
 200             return (TypeVariable<Method>[])getGenericInfo().getTypeParameters();
 201         else
 202             return (TypeVariable<Method>[])new TypeVariable[0];
 203     }
 204 
 205     /**
 206      * Returns a {@code Class} object that represents the formal return type
 207      * of the method represented by this {@code Method} object.
 208      *
 209      * @return the return type for the method this object represents
 210      */
 211     public Class<?> getReturnType() {
 212         return returnType;
 213     }
 214 
 215     /**
 216      * Returns a {@code Type} object that represents the formal return
 217      * type of the method represented by this {@code Method} object.
 218      *
 219      * <p>If the return type is a parameterized type,
 220      * the {@code Type} object returned must accurately reflect
 221      * the actual type parameters used in the source code.
 222      *
 223      * <p>If the return type is a type variable or a parameterized type, it
 224      * is created. Otherwise, it is resolved.
 225      *
 226      * @return  a {@code Type} object that represents the formal return
 227      *     type of the underlying  method
 228      * @throws GenericSignatureFormatError
 229      *     if the generic method signature does not conform to the format
 230      *     specified in
 231      *     <cite>The Java&trade; Virtual Machine Specification</cite>
 232      * @throws TypeNotPresentException if the underlying method's
 233      *     return type refers to a non-existent type declaration
 234      * @throws MalformedParameterizedTypeException if the
 235      *     underlying method's return typed refers to a parameterized
 236      *     type that cannot be instantiated for any reason
 237      * @since 1.5
 238      */
 239     public Type getGenericReturnType() {
 240       if (getGenericSignature() != null) {
 241         return getGenericInfo().getReturnType();
 242       } else { return getReturnType();}
 243     }
 244 
 245     /**
 246      * {@inheritDoc}
 247      */
 248     @Override
 249     public Class<?>[] getParameterTypes() {
 250         return parameterTypes.clone();
 251     }
 252 
 253     /**
 254      * {@inheritDoc}
 255      * @throws GenericSignatureFormatError {@inheritDoc}
 256      * @throws TypeNotPresentException {@inheritDoc}
 257      * @throws MalformedParameterizedTypeException {@inheritDoc}
 258      * @since 1.5
 259      */
 260     @Override
 261     public Type[] getGenericParameterTypes() {
 262         return super.getGenericParameterTypes();
 263     }
 264 
 265     /**
 266      * {@inheritDoc}
 267      */
 268     @Override
 269     public Class<?>[] getExceptionTypes() {
 270         return exceptionTypes.clone();
 271     }
 272 
 273     /**
 274      * {@inheritDoc}
 275      * @throws GenericSignatureFormatError {@inheritDoc}
 276      * @throws TypeNotPresentException {@inheritDoc}
 277      * @throws MalformedParameterizedTypeException {@inheritDoc}
 278      * @since 1.5
 279      */
 280     @Override
 281     public Type[] getGenericExceptionTypes() {
 282         return super.getGenericExceptionTypes();
 283     }
 284 
 285     /**
 286      * Compares this {@code Method} against the specified object.  Returns
 287      * true if the objects are the same.  Two {@code Methods} are the same if
 288      * they were declared by the same class and have the same name
 289      * and formal parameter types and return type.
 290      */
 291     public boolean equals(Object obj) {
 292         if (obj != null && obj instanceof Method) {
 293             Method other = (Method)obj;
 294             if ((getDeclaringClass() == other.getDeclaringClass())
 295                 && (getName() == other.getName())) {
 296                 if (!returnType.equals(other.getReturnType()))
 297                     return false;
 298                 return equalParamTypes(parameterTypes, other.parameterTypes);
 299             }
 300         }
 301         return false;
 302     }
 303 
 304     /**
 305      * Returns a hashcode for this {@code Method}.  The hashcode is computed
 306      * as the exclusive-or of the hashcodes for the underlying
 307      * method's declaring class name and the method's name.
 308      */
 309     public int hashCode() {
 310         return getDeclaringClass().getName().hashCode() ^ getName().hashCode();
 311     }
 312 
 313     /**
 314      * Returns a string describing this {@code Method}.  The string is
 315      * formatted as the method access modifiers, if any, followed by
 316      * the method return type, followed by a space, followed by the
 317      * class declaring the method, followed by a period, followed by
 318      * the method name, followed by a parenthesized, comma-separated
 319      * list of the method's formal parameter types. If the method
 320      * throws checked exceptions, the parameter list is followed by a
 321      * space, followed by the word throws followed by a
 322      * comma-separated list of the thrown exception types.
 323      * For example:
 324      * <pre>
 325      *    public boolean java.lang.Object.equals(java.lang.Object)
 326      * </pre>
 327      *
 328      * <p>The access modifiers are placed in canonical order as
 329      * specified by "The Java Language Specification".  This is
 330      * {@code public}, {@code protected} or {@code private} first,
 331      * and then other modifiers in the following order:
 332      * {@code abstract}, {@code static}, {@code final},
 333      * {@code synchronized}, {@code native}, {@code strictfp}.
 334      */
 335     public String toString() {
 336         return sharedToString(Modifier.methodModifiers(),
 337                               parameterTypes,
 338                               exceptionTypes);
 339     }
 340 
 341     @Override
 342     void specificToStringHeader(StringBuilder sb) {
 343         sb.append(Field.getTypeName(getReturnType())).append(' ');
 344         sb.append(Field.getTypeName(getDeclaringClass())).append('.');
 345         sb.append(getName());
 346     }
 347 
 348     /**
 349      * Returns a string describing this {@code Method}, including
 350      * type parameters.  The string is formatted as the method access
 351      * modifiers, if any, followed by an angle-bracketed
 352      * comma-separated list of the method's type parameters, if any,
 353      * followed by the method's generic return type, followed by a
 354      * space, followed by the class declaring the method, followed by
 355      * a period, followed by the method name, followed by a
 356      * parenthesized, comma-separated list of the method's generic
 357      * formal parameter types.
 358      *
 359      * If this method was declared to take a variable number of
 360      * arguments, instead of denoting the last parameter as
 361      * "<tt><i>Type</i>[]</tt>", it is denoted as
 362      * "<tt><i>Type</i>...</tt>".
 363      *
 364      * A space is used to separate access modifiers from one another
 365      * and from the type parameters or return type.  If there are no
 366      * type parameters, the type parameter list is elided; if the type
 367      * parameter list is present, a space separates the list from the
 368      * class name.  If the method is declared to throw exceptions, the
 369      * parameter list is followed by a space, followed by the word
 370      * throws followed by a comma-separated list of the generic thrown
 371      * exception types.  If there are no type parameters, the type
 372      * parameter list is elided.
 373      *
 374      * <p>The access modifiers are placed in canonical order as
 375      * specified by "The Java Language Specification".  This is
 376      * {@code public}, {@code protected} or {@code private} first,
 377      * and then other modifiers in the following order:
 378      * {@code abstract}, {@code static}, {@code final},
 379      * {@code synchronized}, {@code native}, {@code strictfp}.
 380      *
 381      * @return a string describing this {@code Method},
 382      * include type parameters
 383      *
 384      * @since 1.5
 385      */
 386     @Override
 387     public String toGenericString() {
 388         return sharedToGenericString(Modifier.methodModifiers());
 389     }
 390 
 391     @Override
 392     void specificToGenericStringHeader(StringBuilder sb) {
 393         Type genRetType = getGenericReturnType();
 394         sb.append( ((genRetType instanceof Class<?>)?
 395                     Field.getTypeName((Class<?>)genRetType):genRetType.toString()))
 396             .append(' ');
 397 
 398         sb.append(Field.getTypeName(getDeclaringClass())).append('.');
 399         sb.append(getName());
 400     }
 401 
 402     /**
 403      * Invokes the underlying method represented by this {@code Method}
 404      * object, on the specified object with the specified parameters.
 405      * Individual parameters are automatically unwrapped to match
 406      * primitive formal parameters, and both primitive and reference
 407      * parameters are subject to method invocation conversions as
 408      * necessary.
 409      *
 410      * <p>If the underlying method is static, then the specified {@code obj}
 411      * argument is ignored. It may be null.
 412      *
 413      * <p>If the number of formal parameters required by the underlying method is
 414      * 0, the supplied {@code args} array may be of length 0 or null.
 415      *
 416      * <p>If the underlying method is an instance method, it is invoked
 417      * using dynamic method lookup as documented in The Java Language
 418      * Specification, Second Edition, section 15.12.4.4; in particular,
 419      * overriding based on the runtime type of the target object will occur.
 420      *
 421      * <p>If the underlying method is static, the class that declared
 422      * the method is initialized if it has not already been initialized.
 423      *
 424      * <p>If the method completes normally, the value it returns is
 425      * returned to the caller of invoke; if the value has a primitive
 426      * type, it is first appropriately wrapped in an object. However,
 427      * if the value has the type of an array of a primitive type, the
 428      * elements of the array are <i>not</i> wrapped in objects; in
 429      * other words, an array of primitive type is returned.  If the
 430      * underlying method return type is void, the invocation returns
 431      * null.
 432      *
 433      * @param obj  the object the underlying method is invoked from
 434      * @param args the arguments used for the method call
 435      * @return the result of dispatching the method represented by
 436      * this object on {@code obj} with parameters
 437      * {@code args}
 438      *
 439      * @exception IllegalAccessException    if this {@code Method} object
 440      *              is enforcing Java language access control and the underlying
 441      *              method is inaccessible.
 442      * @exception IllegalArgumentException  if the method is an
 443      *              instance method and the specified object argument
 444      *              is not an instance of the class or interface
 445      *              declaring the underlying method (or of a subclass
 446      *              or implementor thereof); if the number of actual
 447      *              and formal parameters differ; if an unwrapping
 448      *              conversion for primitive arguments fails; or if,
 449      *              after possible unwrapping, a parameter value
 450      *              cannot be converted to the corresponding formal
 451      *              parameter type by a method invocation conversion.
 452      * @exception InvocationTargetException if the underlying method
 453      *              throws an exception.
 454      * @exception NullPointerException      if the specified object is null
 455      *              and the method is an instance method.
 456      * @exception ExceptionInInitializerError if the initialization
 457      * provoked by this method fails.
 458      */
 459     public Object invoke(Object obj, Object... args)
 460         throws IllegalAccessException, IllegalArgumentException,
 461            InvocationTargetException
 462     {
 463         if (!override) {
 464             if (!Reflection.quickCheckMemberAccess(clazz, modifiers)) {
 465                 Class<?> caller = Reflection.getCallerClass(1);
 466 
 467                 checkAccess(caller, clazz, obj, modifiers);
 468             }
 469         }
 470         MethodAccessor ma = methodAccessor;             // read volatile
 471         if (ma == null) {
 472             ma = acquireMethodAccessor();
 473         }
 474         return ma.invoke(obj, args);
 475     }
 476 
 477     /**
 478      * Returns {@code true} if this method is a bridge
 479      * method; returns {@code false} otherwise.
 480      *
 481      * @return true if and only if this method is a bridge
 482      * method as defined by the Java Language Specification.
 483      * @since 1.5
 484      */
 485     public boolean isBridge() {
 486         return (getModifiers() & Modifier.BRIDGE) != 0;
 487     }
 488 
 489     /**
 490      * {@inheritDoc}
 491      * @since 1.5
 492      */
 493     @Override
 494     public boolean isVarArgs() {
 495         return super.isVarArgs();
 496     }
 497 
 498     /**
 499      * {@inheritDoc}
 500      * @since 1.5
 501      */
 502     @Override
 503     public boolean isSynthetic() {
 504         return super.isSynthetic();
 505     }
 506 
 507     // NOTE that there is no synchronization used here. It is correct
 508     // (though not efficient) to generate more than one MethodAccessor
 509     // for a given Method. However, avoiding synchronization will
 510     // probably make the implementation more scalable.
 511     private MethodAccessor acquireMethodAccessor() {
 512         // First check to see if one has been created yet, and take it
 513         // if so
 514         MethodAccessor tmp = null;
 515         if (root != null) tmp = root.getMethodAccessor();
 516         if (tmp != null) {
 517             methodAccessor = tmp;
 518         } else {
 519             // Otherwise fabricate one and propagate it up to the root
 520             tmp = reflectionFactory.newMethodAccessor(this);
 521             setMethodAccessor(tmp);
 522         }
 523 
 524         return tmp;
 525     }
 526 
 527     // Returns MethodAccessor for this Method object, not looking up
 528     // the chain to the root
 529     MethodAccessor getMethodAccessor() {
 530         return methodAccessor;
 531     }
 532 
 533     // Sets the MethodAccessor for this Method object and
 534     // (recursively) its root
 535     void setMethodAccessor(MethodAccessor accessor) {
 536         methodAccessor = accessor;
 537         // Propagate up
 538         if (root != null) {
 539             root.setMethodAccessor(accessor);
 540         }
 541     }
 542 
 543     /**
 544      * Returns the default value for the annotation member represented by
 545      * this {@code Method} instance.  If the member is of a primitive type,
 546      * an instance of the corresponding wrapper type is returned. Returns
 547      * null if no default is associated with the member, or if the method
 548      * instance does not represent a declared member of an annotation type.
 549      *
 550      * @return the default value for the annotation member represented
 551      *     by this {@code Method} instance.
 552      * @throws TypeNotPresentException if the annotation is of type
 553      *     {@link Class} and no definition can be found for the
 554      *     default class value.
 555      * @since  1.5
 556      */
 557     public Object getDefaultValue() {
 558         if  (annotationDefault == null)
 559             return null;
 560         Class<?> memberType = AnnotationType.invocationHandlerReturnType(
 561             getReturnType());
 562         Object result = AnnotationParser.parseMemberValue(
 563             memberType, ByteBuffer.wrap(annotationDefault),
 564             sun.misc.SharedSecrets.getJavaLangAccess().
 565                 getConstantPool(getDeclaringClass()),
 566             getDeclaringClass());
 567         if (result instanceof sun.reflect.annotation.ExceptionProxy)
 568             throw new AnnotationFormatError("Invalid default: " + this);
 569         return result;
 570     }
 571 
 572     /**
 573      * {@inheritDoc}
 574      * @throws NullPointerException  {@inheritDoc}
 575      * @since 1.5
 576      */
 577     public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
 578         return super.getAnnotation(annotationClass);
 579     }
 580 
 581     /**
 582      * {@inheritDoc}
 583      * @since 1.5
 584      */
 585     public Annotation[] getDeclaredAnnotations()  {
 586         return super.getDeclaredAnnotations();
 587     }
 588 
 589     /**
 590      * {@inheritDoc}
 591      * @since 1.5
 592      */
 593     @Override
 594     public Annotation[][] getParameterAnnotations() {
 595         return sharedGetParameterAnnotations(parameterTypes, parameterAnnotations);
 596     }
 597 
 598     @Override
 599     void handleParameterNumberMismatch(int resultLength, int numParameters) {
 600         throw new AnnotationFormatError("Parameter annotations don't match number of parameters");
 601     }
 602 }
--- EOF ---