ResourceTypeHelper.java

package com.temenos.interaction.core.resource;

/*
 * #%L
 * interaction-core
 * %%
 * Copyright (C) 2012 - 2013 Temenos Holdings N.V.
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * #L%
 */


import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;

/**
 * Helper class to assert the type and genericType of a resource.
 * type is the class of the resource object and genericType the
 * java.lang.reflect.Type.
 */
public class ResourceTypeHelper {
	/**
	 * Assert the resource type
	 * @param type Class of resource object
	 * @param genericType ParameterType of resource object
	 * @param expectedType Expected class of resource object
	 * @return true/false
	 */
	public static boolean isType(Class<?> type, Type genericType, Type expectedType) {
		return isType(type, genericType, expectedType, null);
	}

	/**
	 * Assert the resource type
	 * @param type Class of resource object
	 * @param genericType ParameterType of resource object
	 * @param expectedType Expected class of resource object
	 * @param expectedTypeParameter Expected ParameterType of resource object
	 * @return true/false
	 */
	public static boolean isType(Class<?> type, Type genericType, Type expectedType, Class<?> expectedTypeParameter) {
		if(type == null) {
			return false;
		}		
		else if(type.equals(expectedType) && expectedTypeParameter == null) {
			return true;
		}
		else if(genericType != null) {
			if(genericType instanceof ParameterizedType) {
				//This is a ParameterizedType such as EntityResource<OEntity>
				ParameterizedType parameterizedType = (ParameterizedType) genericType;
				if(parameterizedType.getRawType().equals(expectedType)) {
					//Check the type e.g. EntityResource
					if(expectedTypeParameter == null) {
						return true;
					}
					else {
						//Check the type parameter, e.g. OEntity 
						Type[] actualTypeArgs = parameterizedType.getActualTypeArguments();
						if(actualTypeArgs.length == 1) {
							Type actualType = actualTypeArgs[0];
							if(actualType instanceof TypeVariable) {
								return getTypeVariableName(actualType).equals(getTypeVariableName(expectedTypeParameter));
							}
							else {
								return actualType.equals(expectedTypeParameter);
							}
						}
					}
				}
			}
			else if (genericType instanceof TypeVariable) {
				TypeVariable<?> typeVariable = (TypeVariable<?>) genericType;
				return getTypeVariableName(typeVariable).equals(getTypeVariableName(expectedTypeParameter));
			}
			else if(type.equals(expectedType) && genericType.equals(expectedTypeParameter)) {
				return true;
			}
		}
		return false;
	}
	
	public static String getTypeVariableName(Object typeObject) {
	    if(null != typeObject && typeObject instanceof TypeVariable<?>) {
	        TypeVariable<?> typeVariable = (TypeVariable<?>) typeObject;
	        return typeVariable.getName();
	    } else if(null != typeObject && typeObject instanceof Class<?>) {
	        Class<?> typeVariable = (Class<?>) typeObject;
            return typeVariable.getSimpleName();
        } else {
	        return null;
	    }
	}
}