/*
* Copyright 2011 <a href="mailto:lincolnbaxter@gmail.com">Lincoln Baxter, III</a>
*
* 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 org.ocpsoft.rewrite.servlet.config;
import java.util.Collections;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import org.ocpsoft.common.pattern.WeightedComparator;
import org.ocpsoft.common.services.ServiceLoader;
import org.ocpsoft.common.util.Iterators;
import org.ocpsoft.common.util.Strings;
import org.ocpsoft.rewrite.config.Condition;
import org.ocpsoft.rewrite.context.EvaluationContext;
import org.ocpsoft.rewrite.servlet.DispatcherType;
import org.ocpsoft.rewrite.servlet.http.event.HttpServletRewrite;
import org.ocpsoft.rewrite.servlet.spi.DispatcherTypeProvider;
/**
* A {@link Condition} that inspects the value of {@link HttpServletRequest#getDispatcherType()}.
*
* @author <a href="mailto:lincolnbaxter@gmail.com">Lincoln Baxter, III</a>
*/
public class DispatchType extends HttpCondition
{
private final static String PROVIDER_KEY = DispatchType.class.getName() + "_PROVIDERS";
private final DispatcherType type;
private DispatchType(final DispatcherType type)
{
this.type = type;
}
@Override
public boolean evaluateHttp(final HttpServletRewrite event, final EvaluationContext context)
{
if (this.type.equals(getDispatcherType(event)))
{
return true;
}
return false;
}
/**
* Determines the {@link DispatcherType} of the current request using the {@link DispatcherTypeProvider} SPI.
*/
private DispatcherType getDispatcherType(final HttpServletRewrite event)
{
for (DispatcherTypeProvider provider : getDispatcherTypeProviders(event)) {
DispatcherType dispatcherType = provider.getDispatcherType(event.getRequest(), event.getServletContext());
if (dispatcherType != null) {
return dispatcherType;
}
}
throw new IllegalStateException("Unable to determine dispatcher type of current request");
}
/**
* Simple caching mechanism for the providers on a per request basis
*/
@SuppressWarnings("unchecked")
private List<DispatcherTypeProvider> getDispatcherTypeProviders(HttpServletRewrite event)
{
List<DispatcherTypeProvider> providers = (List<DispatcherTypeProvider>)
event.getRequest().getAttribute(PROVIDER_KEY);
if (providers == null) {
providers = Iterators.asList(ServiceLoader.loadTypesafe(DispatcherTypeProvider.class).iterator());
Collections.sort(providers, new WeightedComparator());
event.getRequest().setAttribute(PROVIDER_KEY, providers);
}
return providers;
}
/**
* Create a {@link DispatchType} condition that ensures the current {@link HttpServletRewrite} is a
* {@link DispatcherType#FORWARD}
*/
public static DispatchType isForward()
{
return new DispatchType(DispatcherType.FORWARD);
}
/**
* Create a {@link DispatchType} condition that ensures the current {@link HttpServletRewrite} is a
* {@link DispatcherType#REQUEST}
*/
public static DispatchType isRequest()
{
return new DispatchType(DispatcherType.REQUEST);
}
/**
* Create a {@link DispatchType} condition that ensures the current {@link HttpServletRewrite} is a
* {@link DispatcherType#ERROR}
*/
public static DispatchType isError()
{
return new DispatchType(DispatcherType.ERROR);
}
/**
* Create a {@link DispatchType} condition that ensures the current {@link HttpServletRewrite} is a
* {@link DispatcherType#ASYNC}
*/
public static DispatchType isAsync()
{
return new DispatchType(DispatcherType.ASYNC);
}
/**
* Create a {@link DispatchType} condition that ensures the current {@link HttpServletRewrite} is a
* {@link DispatcherType#INCLUDE}
*/
public static DispatchType isInclude()
{
return new DispatchType(DispatcherType.INCLUDE);
}
@Override
public String toString()
{
return "DispatchType.is" + Strings.capitalize(type.toString().toLowerCase() + "()");
}
}