/*
* Copyright (c) 2002-2012 Alibaba Group Holding Limited.
* All rights reserved.
*
* 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.alibaba.citrus.service.resource.impl;
import java.util.Set;
import com.alibaba.citrus.service.resource.Resource;
import com.alibaba.citrus.service.resource.ResourceLister;
import com.alibaba.citrus.service.resource.ResourceListerContext;
import com.alibaba.citrus.service.resource.ResourceLoader;
import com.alibaba.citrus.service.resource.ResourceLoaderContext;
import com.alibaba.citrus.service.resource.ResourceLoadingOption;
import com.alibaba.citrus.util.ToStringBuilder;
import com.alibaba.citrus.util.ToStringBuilder.MapBuilder;
/**
* 代表一个resource name pattern到一组resource loader的映射。
*
* @author Michael Zhou
*/
public class ResourceLoaderMapping extends ResourceMapping {
private ResourceLoader[] loaders;
public ResourceLoader[] getLoaders() {
return loaders;
}
public void setLoaders(ResourceLoader[] loaders) {
this.loaders = loaders;
}
@Override
public String getPatternType() {
return "resource";
}
@Override
protected void init() {
if (loaders == null) {
loaders = new ResourceLoader[0];
}
for (ResourceLoader loader : loaders) {
loader.init(getResourceLoadingService());
}
}
public Resource getResource(ResourceLoaderContext context, Set<ResourceLoadingOption> options) {
Resource firstResult = null;
// 查找所有的loader：
// * 返回第一个存在的resource
// * 假如resource不存在，则返回第一个非空的resource。
// 例如，file-loader在option=FOR_CREATE时，可能返回一个不存在，但可被创建的resource。
for (ResourceLoader loader : loaders) {
Resource resource = loader.getResource(context, options);
if (resource != null) {
if (resource.exists()) {
return resource;
}
if (firstResult == null) {
firstResult = resource;
}
}
}
return firstResult;
}
public String[] list(ResourceListerContext context, Set<ResourceLoadingOption> options) {
for (ResourceLoader loader : loaders) {
if (loader instanceof ResourceLister) {
String[] names = ((ResourceLister) loader).list(context, options);
if (names != null) {
return names;
}
}
}
return null;
}
@Override
public String toString() {
MapBuilder mb = new MapBuilder();
mb.append("pattern", getPatternName());
if (isInternal()) {
mb.append("internal", isInternal());
}
mb.append("loaders", getLoaders());
return new ToStringBuilder().append(getClass().getSimpleName()).append(mb).toString();
}
}