/**
* Copyright 2010 Newcastle University
*
* http://research.ncl.ac.uk/smart/
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.amber.oauth2.rsfilter;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
/**
* @author Maciej Machulak (m.p.machulak@ncl.ac.uk)
* @author Lukasz Moren (lukasz.moren@ncl.ac.uk)
* @author Aad van Moorsel (aad.vanmoorsel@ncl.ac.uk)
*/
public class OAuthUtils {
public static <T> T initiateServletContext(ServletContext context, String key, Class<T> expectedClass)
throws ServletException {
T provider = (T)context.getAttribute(key);
if (provider != null) {
return provider;
}
provider = (T)loadObject(context, key, expectedClass);
// set the provider and validator
context.setAttribute(key, provider);
return provider;
}
public static Object loadObject(ServletContext context, String classParamName, Class expectedClass)
throws ServletException {
Object ob = null;
String providerClassName = context.getInitParameter(classParamName);
if (isEmpty(providerClassName)) {
throw new ServletException(classParamName + " context param required");
}
try {
Class<?> clazz = Class.forName(providerClassName);
if (!expectedClass.isAssignableFrom(clazz)) {
throw new ServletException(classParamName + " class: " + providerClassName
+ " must be an instance of: " + expectedClass.getName());
}
ob = createObjectFromClassName(clazz);
} catch (ClassNotFoundException e) {
throw new ServletException(classParamName + " class " + providerClassName + " not found");
} catch (Exception e) {
throw new ServletException("Cannot instantiate: " + providerClassName);
}
return ob;
}
public static Object createObjectFromClassName(Class clazz)
throws IllegalAccessException, InstantiationException {
return clazz.newInstance();
}
public static boolean isEmpty(String value) {
return value == null || "".equals(value);
}
}