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/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2008, Red Hat Middleware LLC or third-party contributors as
* indicated by the @author tags or express copyright attribution
* statements applied by the authors. All third-party contributions are
* distributed under license by Red Hat Middleware LLC.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*
*/
package org.hibernate.util;
import java.lang.reflect.Constructor;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import org.hibernate.AssertionFailure;
import org.hibernate.MappingException;
import org.hibernate.PropertyNotFoundException;
import org.hibernate.property.BasicPropertyAccessor;
import org.hibernate.property.DirectPropertyAccessor;
import org.hibernate.property.Getter;
import org.hibernate.property.PropertyAccessor;
import org.hibernate.type.PrimitiveType;
import org.hibernate.type.Type;
/**
* Utility class for various reflection operations.
*
* @author Gavin King
* @author Steve Ebersole
*/
public final class ReflectHelper {
//TODO: this dependency is kinda Bad
private static final PropertyAccessor BASIC_PROPERTY_ACCESSOR = new BasicPropertyAccessor();
private static final PropertyAccessor DIRECT_PROPERTY_ACCESSOR = new DirectPropertyAccessor();
public static final Class[] NO_PARAM_SIGNATURE = new Class[0];
public static final Object[] NO_PARAMS = new Object[0];
public static final Class[] SINGLE_OBJECT_PARAM_SIGNATURE = new Class[] { Object.class };
private static final Method OBJECT_EQUALS;
private static final Method OBJECT_HASHCODE;
static {
Method eq;
Method hash;
try {
eq = extractEqualsMethod( Object.class );
hash = extractHashCodeMethod( Object.class );
}
catch ( Exception e ) {
throw new AssertionFailure( "Could not find Object.equals() or Object.hashCode()", e );
}
OBJECT_EQUALS = eq;
OBJECT_HASHCODE = hash;
}
/**
* Disallow instantiation of ReflectHelper.
*/
private ReflectHelper() {
}
/**
* Encapsulation of getting hold of a class's {@link Object#equals equals} method.
*
* @param clazz The class from which to extract the equals method.
* @return The equals method reference
* @throws NoSuchMethodException Should indicate an attempt to extract equals method from interface.
*/
public static Method extractEqualsMethod(Class clazz) throws NoSuchMethodException {
return clazz.getMethod( "equals", SINGLE_OBJECT_PARAM_SIGNATURE );
}
/**
* Encapsulation of getting hold of a class's {@link Object#hashCode hashCode} method.
*
* @param clazz The class from which to extract the hashCode method.
* @return The hashCode method reference
* @throws NoSuchMethodException Should indicate an attempt to extract hashCode method from interface.
*/
public static Method extractHashCodeMethod(Class clazz) throws NoSuchMethodException {
return clazz.getMethod( "hashCode", NO_PARAM_SIGNATURE );
}
/**
* Determine if the given class defines an {@link Object#equals} override.
*
* @param clazz The class to check
* @return True if clazz defines an equals override.
*/
public static boolean overridesEquals(Class clazz) {
Method equals;
try {
equals = extractEqualsMethod( clazz );
}
catch ( NoSuchMethodException nsme ) {
return false; //its an interface so we can't really tell anything...
}
return !OBJECT_EQUALS.equals( equals );
}
/**
* Determine if the given class defines a {@link Object#hashCode} override.
*
* @param clazz The class to check
* @return True if clazz defines an hashCode override.
*/
public static boolean overridesHashCode(Class clazz) {
Method hashCode;
try {
hashCode = extractHashCodeMethod( clazz );
}
catch ( NoSuchMethodException nsme ) {
return false; //its an interface so we can't really tell anything...
}
return !OBJECT_HASHCODE.equals( hashCode );
}
/**
* Determine if the given class implements the given interface.
*
* @param clazz The class to check
* @param intf The interface to check it against.
* @return True if the class does implement the interface, false otherwise.
*/
public static boolean implementsInterface(Class clazz, Class intf) {
assert intf.isInterface() : "Interface to check was not an interface";
return intf.isAssignableFrom( clazz );
}
/**
* Perform resolution of a class name.
*
* Here we first check the context classloader, if one, before delegating to
* {@link Class#forName(String, boolean, ClassLoader)} using the caller's classloader
*
* @param name The class name
* @param caller The class from which this call originated (in order to access that class's loader).
* @return The class reference.
* @throws ClassNotFoundException From {@link Class#forName(String, boolean, ClassLoader)}.
*/
public static Class classForName(String name, Class caller) throws ClassNotFoundException {
try {
ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
if ( contextClassLoader != null ) {
return contextClassLoader.loadClass( name );
}
}
catch ( Throwable ignore ) {
}
return Class.forName( name, true, caller.getClassLoader() );
}
/**
* Perform resolution of a class name.
*
* Same as {@link #classForName(String, Class)} except that here we delegate to
* {@link Class#forName(String)} if the context classloader lookup is unsuccessful.
*
* @param name The class name
* @return The class reference.
* @throws ClassNotFoundException From {@link Class#forName(String)}.
*/
public static Class classForName(String name) throws ClassNotFoundException {
try {
ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
if ( contextClassLoader != null ) {
return contextClassLoader.loadClass(name);
}
}
catch ( Throwable ignore ) {
}
return Class.forName( name );
}
/**
* Is this member publicly accessible.
*
* Short-hand for {@link #isPublic(Class, Member)} passing the member + {@link Member#getDeclaringClass()}
*
* @param member The member to check
* @return True if the member is publicly accessible.
*/
public static boolean isPublic(Member member) {
return isPublic( member.getDeclaringClass(), member );
}
/**
* Is this member publicly accessible.
*
* @param clazz The class which defines the member
* @param member The memeber.
* @return True if the member is publicly accessible, false otherwise.
*/
public static boolean isPublic(Class clazz, Member member) {
return Modifier.isPublic( member.getModifiers() ) && Modifier.isPublic( clazz.getModifiers() );
}
/**
* Attempt to resolve the specified property type through reflection.
*
* @param className The name of the class owning the property.
* @param name The name of the property.
* @return The type of the property.
* @throws MappingException Indicates we were unable to locate the property.
*/
public static Class reflectedPropertyClass(String className, String name) throws MappingException {
try {
Class clazz = ReflectHelper.classForName( className );
return getter( clazz, name ).getReturnType();
}
catch ( ClassNotFoundException cnfe ) {
throw new MappingException( "class " + className + " not found while looking for property: " + name, cnfe );
}
}
private static Getter getter(Class clazz, String name) throws MappingException {
try {
return BASIC_PROPERTY_ACCESSOR.getGetter( clazz, name );
}
catch ( PropertyNotFoundException pnfe ) {
return DIRECT_PROPERTY_ACCESSOR.getGetter( clazz, name );
}
}
/**
* Directly retrieve the {@link Getter} reference via the {@link BasicPropertyAccessor}.
*
* @param theClass The class owning the property
* @param name The name of the property
* @return The getter.
* @throws MappingException Indicates we were unable to locate the property.
*/
public static Getter getGetter(Class theClass, String name) throws MappingException {
return BASIC_PROPERTY_ACCESSOR.getGetter( theClass, name );
}
/**
* Resolve a constant to its actual value.
*
* @param name The name
* @return The value
*/
public static Object getConstantValue(String name) {
Class clazz;
try {
clazz = classForName( StringHelper.qualifier( name ) );
}
catch ( Throwable t ) {
return null;
}
try {
return clazz.getField( StringHelper.unqualify( name ) ).get( null );
}
catch ( Throwable t ) {
return null;
}
}
/**
* Retrieve the default (no arg) constructor from the given class.
*
* @param clazz The class for which to retrieve the default ctor.
* @return The default constructor.
* @throws PropertyNotFoundException Indicates there was not publicly accessible, no-arg constructor (todo : why PropertyNotFoundException???)
*/
public static Constructor getDefaultConstructor(Class clazz) throws PropertyNotFoundException {
if ( isAbstractClass( clazz ) ) {
return null;
}
try {
Constructor constructor = clazz.getDeclaredConstructor( NO_PARAM_SIGNATURE );
if ( !isPublic( clazz, constructor ) ) {
constructor.setAccessible( true );
}
return constructor;
}
catch ( NoSuchMethodException nme ) {
throw new PropertyNotFoundException(
"Object class [" + clazz.getName() + "] must declare a default (no-argument) constructor"
);
}
}
/**
* Determine if the given class is declared abstract.
*
* @param clazz The class to check.
* @return True if the class is abstract, false otherwise.
*/
public static boolean isAbstractClass(Class clazz) {
int modifier = clazz.getModifiers();
return Modifier.isAbstract(modifier) || Modifier.isInterface(modifier);
}
/**
* Determine is the given class is declared final.
*
* @param clazz The class to check.
* @return True if the class is final, flase otherwise.
*/
public static boolean isFinalClass(Class clazz) {
return Modifier.isFinal( clazz.getModifiers() );
}
/**
* Retrieve a constructor for the given class, with arguments matching the specified Hibernate mapping
* {@link Type types}.
*
* @param clazz The class needing instantiation
* @param types The types representing the required ctor param signature
* @return The matching constructor.
* @throws PropertyNotFoundException Indicates we could not locate an appropriate constructor (todo : again with PropertyNotFoundException???)
*/
public static Constructor getConstructor(Class clazz, Type[] types) throws PropertyNotFoundException {
final Constructor[] candidates = clazz.getConstructors();
for ( int i = 0; i < candidates.length; i++ ) {
final Constructor constructor = candidates[i];
final Class[] params = constructor.getParameterTypes();
if ( params.length == types.length ) {
boolean found = true;
for ( int j = 0; j < params.length; j++ ) {
final boolean ok = params[j].isAssignableFrom( types[j].getReturnedClass() ) || (
types[j] instanceof PrimitiveType &&
params[j] == ( ( PrimitiveType ) types[j] ).getPrimitiveClass()
);
if ( !ok ) {
found = false;
break;
}
}
if ( found ) {
if ( !isPublic( clazz, constructor ) ) {
constructor.setAccessible( true );
}
return constructor;
}
}
}
throw new PropertyNotFoundException( "no appropriate constructor in class: " + clazz.getName() );
}
public static Method getMethod(Class clazz, Method method) {
try {
return clazz.getMethod( method.getName(), method.getParameterTypes() );
}
catch (Exception e) {
return null;
}
}
}
