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/* * Copyright 2002-2019 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 * * https://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.beans.factory.xml; import java.io.FileNotFoundException; import java.io.IOException; import java.util.Map; import java.util.Properties; import java.util.concurrent.ConcurrentHashMap; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.xml.sax.EntityResolver; import org.xml.sax.InputSource; import org.springframework.core.io.ClassPathResource; import org.springframework.core.io.Resource; import org.springframework.core.io.support.PropertiesLoaderUtils; import org.springframework.lang.Nullable; import org.springframework.util.Assert; import org.springframework.util.CollectionUtils; /** * {@link EntityResolver} implementation that attempts to resolve schema URLs into * local {@link ClassPathResource classpath resources} using a set of mappings files. * * <p>By default, this class will look for mapping files in the classpath using the * pattern: {@code META-INF/spring.schemas} allowing for multiple files to exist on * the classpath at any one time. * * <p>The format of {@code META-INF/spring.schemas} is a properties file where each line * should be of the form {@code systemId=schema-location} where {@code schema-location} * should also be a schema file in the classpath. Since {@code systemId} is commonly a * URL, one must be careful to escape any ':' characters which are treated as delimiters * in properties files. * * <p>The pattern for the mapping files can be overridden using the * {@link #PluggableSchemaResolver(ClassLoader, String)} constructor. * * @author Rob Harrop * @author Juergen Hoeller * @since 2.0 */ public class PluggableSchemaResolver implements EntityResolver { /** * The location of the file that defines schema mappings. * Can be present in multiple JAR files. */ public static final String DEFAULT_SCHEMA_MAPPINGS_LOCATION = "META-INF/spring.schemas"; private static final Log logger = LogFactory.getLog(PluggableSchemaResolver.class); @Nullable private final ClassLoader classLoader; private final String schemaMappingsLocation; /** Stores the mapping of schema URL -> local schema path. */ @Nullable private volatile Map<String, String> schemaMappings; /** * Loads the schema URL -> schema file location mappings using the default * mapping file pattern "META-INF/spring.schemas". * @param classLoader the ClassLoader to use for loading * (can be {@code null}) to use the default ClassLoader) * @see PropertiesLoaderUtils#loadAllProperties(String, ClassLoader) */ public PluggableSchemaResolver(@Nullable ClassLoader classLoader) { this.classLoader = classLoader; this.schemaMappingsLocation = DEFAULT_SCHEMA_MAPPINGS_LOCATION; } /** * Loads the schema URL -> schema file location mappings using the given * mapping file pattern. * @param classLoader the ClassLoader to use for loading * (can be {@code null}) to use the default ClassLoader) * @param schemaMappingsLocation the location of the file that defines schema mappings * (must not be empty) * @see PropertiesLoaderUtils#loadAllProperties(String, ClassLoader) */ public PluggableSchemaResolver(@Nullable ClassLoader classLoader, String schemaMappingsLocation) { Assert.hasText(schemaMappingsLocation, "'schemaMappingsLocation' must not be empty"); this.classLoader = classLoader; this.schemaMappingsLocation = schemaMappingsLocation; } @Override @Nullable public InputSource resolveEntity(@Nullable String publicId, @Nullable String systemId) throws IOException { if (logger.isTraceEnabled()) { logger.trace("Trying to resolve XML entity with public id [" + publicId + "] and system id [" + systemId + "]"); } if (systemId != null) { String resourceLocation = getSchemaMappings().get(systemId); if (resourceLocation == null && systemId.startsWith("https:")) { // Retrieve canonical http schema mapping even for https declaration resourceLocation = getSchemaMappings().get("http:" + systemId.substring(6)); } if (resourceLocation != null) { Resource resource = new ClassPathResource(resourceLocation, this.classLoader); try { InputSource source = new InputSource(resource.getInputStream()); source.setPublicId(publicId); source.setSystemId(systemId); if (logger.isTraceEnabled()) { logger.trace("Found XML schema [" + systemId + "] in classpath: " + resourceLocation); } return source; } catch (FileNotFoundException ex) { if (logger.isDebugEnabled()) { logger.debug("Could not find XML schema [" + systemId + "]: " + resource, ex); } } } } // Fall back to the parser's default behavior. return null; } /** * Load the specified schema mappings lazily. */ private Map<String, String> getSchemaMappings() { Map<String, String> schemaMappings = this.schemaMappings; if (schemaMappings == null) { synchronized (this) { schemaMappings = this.schemaMappings; if (schemaMappings == null) { if (logger.isTraceEnabled()) { logger.trace("Loading schema mappings from [" + this.schemaMappingsLocation + "]"); } try { Properties mappings = PropertiesLoaderUtils.loadAllProperties(this.schemaMappingsLocation, this.classLoader); if (logger.isTraceEnabled()) { logger.trace("Loaded schema mappings: " + mappings); } schemaMappings = new ConcurrentHashMap<>(mappings.size()); CollectionUtils.mergePropertiesIntoMap(mappings, schemaMappings); this.schemaMappings = schemaMappings; } catch (IOException ex) { throw new IllegalStateException("Unable to load schema mappings from location [" + this.schemaMappingsLocation + "]", ex); } } } } return schemaMappings; } @Override public String toString() { return "EntityResolver using schema mappings " + getSchemaMappings(); } }