ContextRegionBeanDefinitionParser.java

/*
 * Copyright 2013-2014 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.cloud.aws.context.config.xml;

import org.springframework.beans.factory.BeanDefinitionStoreException;
import org.springframework.beans.factory.support.AbstractBeanDefinition;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.xml.AbstractBeanDefinitionParser;
import org.springframework.beans.factory.xml.ParserContext;
import org.springframework.util.StringUtils;
import org.w3c.dom.Element;

import static org.springframework.cloud.aws.core.config.AmazonWebserviceClientConfigurationUtils.replaceDefaultRegionProvider;

public class ContextRegionBeanDefinitionParser extends AbstractBeanDefinitionParser {

    static final String CONTEXT_REGION_PROVIDER_BEAN_NAME = "regionProvider";

    @Override
    protected String resolveId(Element element, AbstractBeanDefinition definition, ParserContext parserContext) throws BeanDefinitionStoreException {
        return CONTEXT_REGION_PROVIDER_BEAN_NAME;
    }

    @Override
    protected AbstractBeanDefinition parseInternal(Element element, ParserContext parserContext) {
        if (parserContext.getRegistry().containsBeanDefinition(CONTEXT_REGION_PROVIDER_BEAN_NAME)) {
            parserContext.getReaderContext().error("Multiple <context-region/> elements detected. The <context-region/> element is only allowed once per application context", element);
        }

        if (isAutoDetect(element) && (StringUtils.hasText(element.getAttribute("region")) || StringUtils.hasText(element.getAttribute("region-provider")))) {
            parserContext.getReaderContext().error("The attribute 'auto-detect' can only be enabled without a region or region-provider specified", element);
            return null;
        }

        if (!isAutoDetect(element) && !StringUtils.hasText(element.getAttribute("region")) && !StringUtils.hasText(element.getAttribute("region-provider"))) {
            parserContext.getReaderContext().error("Either auto-detect must be enabled, or a region or region-provider must be specified", element);
            return null;
        }

        //Replace the default region provider with this one
        replaceDefaultRegionProvider(parserContext.getRegistry(), CONTEXT_REGION_PROVIDER_BEAN_NAME);

        if (StringUtils.hasText(element.getAttribute("region-provider"))) {
            parserContext.getRegistry().registerAlias(element.getAttribute("region-provider"), CONTEXT_REGION_PROVIDER_BEAN_NAME);
            return null;
        } else if (StringUtils.hasText(element.getAttribute("region"))) {
            BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition("org.springframework.cloud.aws.core.region.StaticRegionProvider");
            builder.addConstructorArgValue(element.getAttribute("region"));
            return builder.getBeanDefinition();
        } else if (isAutoDetect(element)) {
            BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition("org.springframework.cloud.aws.core.region.Ec2MetadataRegionProvider");
            return builder.getBeanDefinition();
        }
        return null;
    }

    @Override
    protected boolean shouldGenerateId() {
        return false;
    }

    private static boolean isAutoDetect(Element element) {
        return StringUtils.hasText(element.getAttribute("auto-detect")) &&
                Boolean.TRUE.toString().equalsIgnoreCase(element.getAttribute("auto-detect"));
    }
}