org.springframework.web.servlet.resource.DefaultResourceResolverChain Maven / Gradle / Ivy
/*
* Copyright 2002-2016 the original author or authors.
*
* 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.springframework.web.servlet.resource;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import org.springframework.core.io.Resource;
import org.springframework.util.Assert;
/**
* A default implementation of {@link ResourceResolverChain} for invoking a list
* of {@link ResourceResolver}s.
*
* @author Jeremy Grelle
* @author Rossen Stoyanchev
* @author Sam Brannen
* @since 4.1
*/
class DefaultResourceResolverChain implements ResourceResolverChain {
private final List resolvers = new ArrayList();
private int index = -1;
public DefaultResourceResolverChain(List resolvers) {
if (resolvers != null) {
this.resolvers.addAll(resolvers);
}
}
@Override
public Resource resolveResource(HttpServletRequest request, String requestPath, List locations) {
ResourceResolver resolver = getNext();
if (resolver == null) {
return null;
}
try {
return resolver.resolveResource(request, requestPath, locations, this);
}
finally {
this.index--;
}
}
@Override
public String resolveUrlPath(String resourcePath, List locations) {
ResourceResolver resolver = getNext();
if (resolver == null) {
return null;
}
try {
return resolver.resolveUrlPath(resourcePath, locations, this);
}
finally {
this.index--;
}
}
private ResourceResolver getNext() {
Assert.state(this.index <= this.resolvers.size(),
"Current index exceeds the number of configured ResourceResolvers");
if (this.index == (this.resolvers.size() - 1)) {
return null;
}
this.index++;
return this.resolvers.get(this.index);
}
}