Java example source code file (Method.java)
The Method.java Java example source code/*
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* accompanied this code).
*
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package java.lang.reflect;
import sun.reflect.CallerSensitive;
import sun.reflect.MethodAccessor;
import sun.reflect.Reflection;
import sun.reflect.generics.repository.MethodRepository;
import sun.reflect.generics.factory.CoreReflectionFactory;
import sun.reflect.generics.factory.GenericsFactory;
import sun.reflect.generics.scope.MethodScope;
import sun.reflect.annotation.AnnotationType;
import sun.reflect.annotation.AnnotationParser;
import java.lang.annotation.Annotation;
import java.lang.annotation.AnnotationFormatError;
import java.nio.ByteBuffer;
/**
* A {@code Method} provides information about, and access to, a single method
* on a class or interface. The reflected method may be a class method
* or an instance method (including an abstract method).
*
* <p>A {@code Method} permits widening conversions to occur when matching the
* actual parameters to invoke with the underlying method's formal
* parameters, but it throws an {@code IllegalArgumentException} if a
* narrowing conversion would occur.
*
* @see Member
* @see java.lang.Class
* @see java.lang.Class#getMethods()
* @see java.lang.Class#getMethod(String, Class[])
* @see java.lang.Class#getDeclaredMethods()
* @see java.lang.Class#getDeclaredMethod(String, Class[])
*
* @author Kenneth Russell
* @author Nakul Saraiya
*/
public final class Method extends Executable {
private Class<?> clazz;
private int slot;
// This is guaranteed to be interned by the VM in the 1.4
// reflection implementation
private String name;
private Class<?> returnType;
private Class<?>[] parameterTypes;
private Class<?>[] exceptionTypes;
private int modifiers;
// Generics and annotations support
private transient String signature;
// generic info repository; lazily initialized
private transient MethodRepository genericInfo;
private byte[] annotations;
private byte[] parameterAnnotations;
private byte[] annotationDefault;
private volatile MethodAccessor methodAccessor;
// For sharing of MethodAccessors. This branching structure is
// currently only two levels deep (i.e., one root Method and
// potentially many Method objects pointing to it.)
private Method root;
// Generics infrastructure
private String getGenericSignature() {return signature;}
// Accessor for factory
private GenericsFactory getFactory() {
// create scope and factory
return CoreReflectionFactory.make(this, MethodScope.make(this));
}
// Accessor for generic info repository
@Override
MethodRepository getGenericInfo() {
// lazily initialize repository if necessary
if (genericInfo == null) {
// create and cache generic info repository
genericInfo = MethodRepository.make(getGenericSignature(),
getFactory());
}
return genericInfo; //return cached repository
}
/**
* Package-private constructor used by ReflectAccess to enable
* instantiation of these objects in Java code from the java.lang
* package via sun.reflect.LangReflectAccess.
*/
Method(Class<?> declaringClass,
String name,
Class<?>[] parameterTypes,
Class<?> returnType,
Class<?>[] checkedExceptions,
int modifiers,
int slot,
String signature,
byte[] annotations,
byte[] parameterAnnotations,
byte[] annotationDefault) {
this.clazz = declaringClass;
this.name = name;
this.parameterTypes = parameterTypes;
this.returnType = returnType;
this.exceptionTypes = checkedExceptions;
this.modifiers = modifiers;
this.slot = slot;
this.signature = signature;
this.annotations = annotations;
this.parameterAnnotations = parameterAnnotations;
this.annotationDefault = annotationDefault;
}
/**
* Package-private routine (exposed to java.lang.Class via
* ReflectAccess) which returns a copy of this Method. The copy's
* "root" field points to this Method.
*/
Method copy() {
// This routine enables sharing of MethodAccessor objects
// among Method objects which refer to the same underlying
// method in the VM. (All of this contortion is only necessary
// because of the "accessibility" bit in AccessibleObject,
// which implicitly requires that new java.lang.reflect
// objects be fabricated for each reflective call on Class
// objects.)
Method res = new Method(clazz, name, parameterTypes, returnType,
exceptionTypes, modifiers, slot, signature,
annotations, parameterAnnotations, annotationDefault);
res.root = this;
// Might as well eagerly propagate this if already present
res.methodAccessor = methodAccessor;
return res;
}
@Override
boolean hasGenericInformation() {
return (getGenericSignature() != null);
}
@Override
byte[] getAnnotationBytes() {
return annotations;
}
/**
* {@inheritDoc}
*/
@Override
public Class<?> getDeclaringClass() {
return clazz;
}
/**
* Returns the name of the method represented by this {@code Method}
* object, as a {@code String}.
*/
@Override
public String getName() {
return name;
}
/**
* {@inheritDoc}
*/
@Override
public int getModifiers() {
return modifiers;
}
/**
* {@inheritDoc}
* @throws GenericSignatureFormatError {@inheritDoc}
* @since 1.5
*/
@Override
@SuppressWarnings({"rawtypes", "unchecked"})
public TypeVariable<Method>[] getTypeParameters() {
if (getGenericSignature() != null)
return (TypeVariable<Method>[])getGenericInfo().getTypeParameters();
else
return (TypeVariable<Method>[])new TypeVariable[0];
}
/**
* Returns a {@code Class} object that represents the formal return type
* of the method represented by this {@code Method} object.
*
* @return the return type for the method this object represents
*/
public Class<?> getReturnType() {
return returnType;
}
/**
* Returns a {@code Type} object that represents the formal return
* type of the method represented by this {@code Method} object.
*
* <p>If the return type is a parameterized type,
* the {@code Type} object returned must accurately reflect
* the actual type parameters used in the source code.
*
* <p>If the return type is a type variable or a parameterized type, it
* is created. Otherwise, it is resolved.
*
* @return a {@code Type} object that represents the formal return
* type of the underlying method
* @throws GenericSignatureFormatError
* if the generic method signature does not conform to the format
* specified in
* <cite>The Java™ Virtual Machine Specification
* @throws TypeNotPresentException if the underlying method's
* return type refers to a non-existent type declaration
* @throws MalformedParameterizedTypeException if the
* underlying method's return typed refers to a parameterized
* type that cannot be instantiated for any reason
* @since 1.5
*/
public Type getGenericReturnType() {
if (getGenericSignature() != null) {
return getGenericInfo().getReturnType();
} else { return getReturnType();}
}
/**
* {@inheritDoc}
*/
@Override
public Class<?>[] getParameterTypes() {
return parameterTypes.clone();
}
/**
* {@inheritDoc}
*/
public int getParameterCount() { return parameterTypes.length; }
/**
* {@inheritDoc}
* @throws GenericSignatureFormatError {@inheritDoc}
* @throws TypeNotPresentException {@inheritDoc}
* @throws MalformedParameterizedTypeException {@inheritDoc}
* @since 1.5
*/
@Override
public Type[] getGenericParameterTypes() {
return super.getGenericParameterTypes();
}
/**
* {@inheritDoc}
*/
@Override
public Class<?>[] getExceptionTypes() {
return exceptionTypes.clone();
}
/**
* {@inheritDoc}
* @throws GenericSignatureFormatError {@inheritDoc}
* @throws TypeNotPresentException {@inheritDoc}
* @throws MalformedParameterizedTypeException {@inheritDoc}
* @since 1.5
*/
@Override
public Type[] getGenericExceptionTypes() {
return super.getGenericExceptionTypes();
}
/**
* Compares this {@code Method} against the specified object. Returns
* true if the objects are the same. Two {@code Methods} are the same if
* they were declared by the same class and have the same name
* and formal parameter types and return type.
*/
public boolean equals(Object obj) {
if (obj != null && obj instanceof Method) {
Method other = (Method)obj;
if ((getDeclaringClass() == other.getDeclaringClass())
&& (getName() == other.getName())) {
if (!returnType.equals(other.getReturnType()))
return false;
return equalParamTypes(parameterTypes, other.parameterTypes);
}
}
return false;
}
/**
* Returns a hashcode for this {@code Method}. The hashcode is computed
* as the exclusive-or of the hashcodes for the underlying
* method's declaring class name and the method's name.
*/
public int hashCode() {
return getDeclaringClass().getName().hashCode() ^ getName().hashCode();
}
/**
* Returns a string describing this {@code Method}. The string is
* formatted as the method access modifiers, if any, followed by
* the method return type, followed by a space, followed by the
* class declaring the method, followed by a period, followed by
* the method name, followed by a parenthesized, comma-separated
* list of the method's formal parameter types. If the method
* throws checked exceptions, the parameter list is followed by a
* space, followed by the word throws followed by a
* comma-separated list of the thrown exception types.
* For example:
* <pre>
* public boolean java.lang.Object.equals(java.lang.Object)
* </pre>
*
* <p>The access modifiers are placed in canonical order as
* specified by "The Java Language Specification". This is
* {@code public}, {@code protected} or {@code private} first,
* and then other modifiers in the following order:
* {@code abstract}, {@code default}, {@code static}, {@code final},
* {@code synchronized}, {@code native}, {@code strictfp}.
*
* @return a string describing this {@code Method}
*
* @jls 8.4.3 Method Modifiers
*/
public String toString() {
return sharedToString(Modifier.methodModifiers(),
isDefault(),
parameterTypes,
exceptionTypes);
}
@Override
void specificToStringHeader(StringBuilder sb) {
sb.append(getReturnType().getTypeName()).append(' ');
sb.append(getDeclaringClass().getTypeName()).append('.');
sb.append(getName());
}
/**
* Returns a string describing this {@code Method}, including
* type parameters. The string is formatted as the method access
* modifiers, if any, followed by an angle-bracketed
* comma-separated list of the method's type parameters, if any,
* followed by the method's generic return type, followed by a
* space, followed by the class declaring the method, followed by
* a period, followed by the method name, followed by a
* parenthesized, comma-separated list of the method's generic
* formal parameter types.
*
* If this method was declared to take a variable number of
* arguments, instead of denoting the last parameter as
* "<tt>Type[]", it is denoted as
* "<tt>Type...".
*
* A space is used to separate access modifiers from one another
* and from the type parameters or return type. If there are no
* type parameters, the type parameter list is elided; if the type
* parameter list is present, a space separates the list from the
* class name. If the method is declared to throw exceptions, the
* parameter list is followed by a space, followed by the word
* throws followed by a comma-separated list of the generic thrown
* exception types.
*
* <p>The access modifiers are placed in canonical order as
* specified by "The Java Language Specification". This is
* {@code public}, {@code protected} or {@code private} first,
* and then other modifiers in the following order:
* {@code abstract}, {@code default}, {@code static}, {@code final},
* {@code synchronized}, {@code native}, {@code strictfp}.
*
* @return a string describing this {@code Method},
* include type parameters
*
* @since 1.5
*
* @jls 8.4.3 Method Modifiers
*/
@Override
public String toGenericString() {
return sharedToGenericString(Modifier.methodModifiers(), isDefault());
}
@Override
void specificToGenericStringHeader(StringBuilder sb) {
Type genRetType = getGenericReturnType();
sb.append(genRetType.getTypeName()).append(' ');
sb.append(getDeclaringClass().getTypeName()).append('.');
sb.append(getName());
}
/**
* Invokes the underlying method represented by this {@code Method}
* object, on the specified object with the specified parameters.
* Individual parameters are automatically unwrapped to match
* primitive formal parameters, and both primitive and reference
* parameters are subject to method invocation conversions as
* necessary.
*
* <p>If the underlying method is static, then the specified {@code obj}
* argument is ignored. It may be null.
*
* <p>If the number of formal parameters required by the underlying method is
* 0, the supplied {@code args} array may be of length 0 or null.
*
* <p>If the underlying method is an instance method, it is invoked
* using dynamic method lookup as documented in The Java Language
* Specification, Second Edition, section 15.12.4.4; in particular,
* overriding based on the runtime type of the target object will occur.
*
* <p>If the underlying method is static, the class that declared
* the method is initialized if it has not already been initialized.
*
* <p>If the method completes normally, the value it returns is
* returned to the caller of invoke; if the value has a primitive
* type, it is first appropriately wrapped in an object. However,
* if the value has the type of an array of a primitive type, the
* elements of the array are <i>not wrapped in objects; in
* other words, an array of primitive type is returned. If the
* underlying method return type is void, the invocation returns
* null.
*
* @param obj the object the underlying method is invoked from
* @param args the arguments used for the method call
* @return the result of dispatching the method represented by
* this object on {@code obj} with parameters
* {@code args}
*
* @exception IllegalAccessException if this {@code Method} object
* is enforcing Java language access control and the underlying
* method is inaccessible.
* @exception IllegalArgumentException if the method is an
* instance method and the specified object argument
* is not an instance of the class or interface
* declaring the underlying method (or of a subclass
* or implementor thereof); if the number of actual
* and formal parameters differ; if an unwrapping
* conversion for primitive arguments fails; or if,
* after possible unwrapping, a parameter value
* cannot be converted to the corresponding formal
* parameter type by a method invocation conversion.
* @exception InvocationTargetException if the underlying method
* throws an exception.
* @exception NullPointerException if the specified object is null
* and the method is an instance method.
* @exception ExceptionInInitializerError if the initialization
* provoked by this method fails.
*/
@CallerSensitive
public Object invoke(Object obj, Object... args)
throws IllegalAccessException, IllegalArgumentException,
InvocationTargetException
{
if (!override) {
if (!Reflection.quickCheckMemberAccess(clazz, modifiers)) {
Class<?> caller = Reflection.getCallerClass();
checkAccess(caller, clazz, obj, modifiers);
}
}
MethodAccessor ma = methodAccessor; // read volatile
if (ma == null) {
ma = acquireMethodAccessor();
}
return ma.invoke(obj, args);
}
/**
* Returns {@code true} if this method is a bridge
* method; returns {@code false} otherwise.
*
* @return true if and only if this method is a bridge
* method as defined by the Java Language Specification.
* @since 1.5
*/
public boolean isBridge() {
return (getModifiers() & Modifier.BRIDGE) != 0;
}
/**
* {@inheritDoc}
* @since 1.5
*/
@Override
public boolean isVarArgs() {
return super.isVarArgs();
}
/**
* {@inheritDoc}
* @jls 13.1 The Form of a Binary
* @since 1.5
*/
@Override
public boolean isSynthetic() {
return super.isSynthetic();
}
/**
* Returns {@code true} if this method is a default
* method; returns {@code false} otherwise.
*
* A default method is a public non-abstract instance method, that
* is, a non-static method with a body, declared in an interface
* type.
*
* @return true if and only if this method is a default
* method as defined by the Java Language Specification.
* @since 1.8
*/
public boolean isDefault() {
// Default methods are public non-abstract instance methods
// declared in an interface.
return ((getModifiers() & (Modifier.ABSTRACT | Modifier.PUBLIC | Modifier.STATIC)) ==
Modifier.PUBLIC) && getDeclaringClass().isInterface();
}
// NOTE that there is no synchronization used here. It is correct
// (though not efficient) to generate more than one MethodAccessor
// for a given Method. However, avoiding synchronization will
// probably make the implementation more scalable.
private MethodAccessor acquireMethodAccessor() {
// First check to see if one has been created yet, and take it
// if so
MethodAccessor tmp = null;
if (root != null) tmp = root.getMethodAccessor();
if (tmp != null) {
methodAccessor = tmp;
} else {
// Otherwise fabricate one and propagate it up to the root
tmp = reflectionFactory.newMethodAccessor(this);
setMethodAccessor(tmp);
}
return tmp;
}
// Returns MethodAccessor for this Method object, not looking up
// the chain to the root
MethodAccessor getMethodAccessor() {
return methodAccessor;
}
// Sets the MethodAccessor for this Method object and
// (recursively) its root
void setMethodAccessor(MethodAccessor accessor) {
methodAccessor = accessor;
// Propagate up
if (root != null) {
root.setMethodAccessor(accessor);
}
}
/**
* Returns the default value for the annotation member represented by
* this {@code Method} instance. If the member is of a primitive type,
* an instance of the corresponding wrapper type is returned. Returns
* null if no default is associated with the member, or if the method
* instance does not represent a declared member of an annotation type.
*
* @return the default value for the annotation member represented
* by this {@code Method} instance.
* @throws TypeNotPresentException if the annotation is of type
* {@link Class} and no definition can be found for the
* default class value.
* @since 1.5
*/
public Object getDefaultValue() {
if (annotationDefault == null)
return null;
Class<?> memberType = AnnotationType.invocationHandlerReturnType(
getReturnType());
Object result = AnnotationParser.parseMemberValue(
memberType, ByteBuffer.wrap(annotationDefault),
sun.misc.SharedSecrets.getJavaLangAccess().
getConstantPool(getDeclaringClass()),
getDeclaringClass());
if (result instanceof sun.reflect.annotation.ExceptionProxy)
throw new AnnotationFormatError("Invalid default: " + this);
return result;
}
/**
* {@inheritDoc}
* @throws NullPointerException {@inheritDoc}
* @since 1.5
*/
public <T extends Annotation> T getAnnotation(Class
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