ComponentUtil.java

/**
 *    Copyright 2017 ICF Olson
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package com.citytechinc.cq.component.util;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.List;

import javassist.CtField;
import javassist.CtMember;

import com.citytechinc.cq.component.dialog.exception.InvalidComponentFieldException;

public class ComponentUtil {

	/**
	 * Retrieves a field for a Class. To allow for the retrieval of inherited
	 * fields, the class hierarchy is traversed upwards starting at the provided
	 * class. If the top of the hierarchy is reached without finding a field of
	 * the specified name, null is returned.
	 * 
	 * @param clazz
	 * @param fieldName
	 * @return The Field specified by the provided name or null if no such field
	 *         could be found for the Class or its parents.
	 */
	public static Field getField(Class<?> clazz, String fieldName) {
		Field retField = null;
		Class<?> curClass = clazz;

		while (retField == null && curClass != null) {
			try {
				retField = curClass.getDeclaredField(fieldName);
				curClass = curClass.getSuperclass();
			} catch (Exception e) {

			} finally {
				curClass = curClass.getSuperclass();
			}
		}

		return retField;
	}

	/**
	 * Retrieves a Method for a Class.
	 * 
	 * @param clazz
	 * @param fieldName
	 * @return The Method specified by the provided name or null if no such
	 *         Method could be found for the Class.
	 */
	public static Method getMethod(Class<?> clazz, String methodName) {
		for (Method method : clazz.getMethods()) {
			if (method.getName().equals(methodName)) {
				return method;
			}
		}

		return null;
	}

	public static Class<?> getTypeForMember(CtMember ctMember, Class<?> containingClass)
		throws InvalidComponentFieldException {
		Class<?> type = null;
		Type genericType = null;
		if (ctMember instanceof CtField) {
			Field memberField = getField(containingClass, ctMember.getName());
			type = memberField.getType();
			genericType = memberField.getGenericType();
		} else {
			Method memberMethod = getMethod(containingClass, ctMember.getName());
			type = memberMethod.getReturnType();
			genericType = memberMethod.getGenericReturnType();
		}
		if (List.class.isAssignableFrom(type)) {
			ParameterizedType parameterizedType = (ParameterizedType) genericType;
			if (parameterizedType.getActualTypeArguments().length == 0
				|| parameterizedType.getActualTypeArguments().length > 1) {
				throw new InvalidComponentFieldException(
					"List dialog property found with a paramaterized type count not equal to 1");
			}
			type = (Class<?>) parameterizedType.getActualTypeArguments()[0];
		}
		return type;
	}
}