org.springframework.beans.factory.xml.DelegatingEntityResolver.java Source code

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Here is the source code for org.springframework.beans.factory.xml.DelegatingEntityResolver.java

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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.IOException;

import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

import org.springframework.lang.Nullable;
import org.springframework.util.Assert;

/**
 * {@link EntityResolver} implementation that delegates to a {@link BeansDtdResolver}
 * and a {@link PluggableSchemaResolver} for DTDs and XML schemas, respectively.
 *
 * @author Rob Harrop
 * @author Juergen Hoeller
 * @author Rick Evans
 * @since 2.0
 * @see BeansDtdResolver
 * @see PluggableSchemaResolver
 */
public class DelegatingEntityResolver implements EntityResolver {

    /** Suffix for DTD files. */
    public static final String DTD_SUFFIX = ".dtd";

    /** Suffix for schema definition files. */
    public static final String XSD_SUFFIX = ".xsd";

    private final EntityResolver dtdResolver;

    private final EntityResolver schemaResolver;

    /**
     * Create a new DelegatingEntityResolver that delegates to
     * a default {@link BeansDtdResolver} and a default {@link PluggableSchemaResolver}.
     * <p>Configures the {@link PluggableSchemaResolver} with the supplied
     * {@link ClassLoader}.
     * @param classLoader the ClassLoader to use for loading
     * (can be {@code null}) to use the default ClassLoader)
     */
    public DelegatingEntityResolver(@Nullable ClassLoader classLoader) {
        this.dtdResolver = new BeansDtdResolver();
        this.schemaResolver = new PluggableSchemaResolver(classLoader);
    }

    /**
     * Create a new DelegatingEntityResolver that delegates to
     * the given {@link EntityResolver EntityResolvers}.
     * @param dtdResolver the EntityResolver to resolve DTDs with
     * @param schemaResolver the EntityResolver to resolve XML schemas with
     */
    public DelegatingEntityResolver(EntityResolver dtdResolver, EntityResolver schemaResolver) {
        Assert.notNull(dtdResolver, "'dtdResolver' is required");
        Assert.notNull(schemaResolver, "'schemaResolver' is required");
        this.dtdResolver = dtdResolver;
        this.schemaResolver = schemaResolver;
    }

    @Override
    @Nullable
    public InputSource resolveEntity(@Nullable String publicId, @Nullable String systemId)
            throws SAXException, IOException {

        if (systemId != null) {
            if (systemId.endsWith(DTD_SUFFIX)) {
                return this.dtdResolver.resolveEntity(publicId, systemId);
            } else if (systemId.endsWith(XSD_SUFFIX)) {
                return this.schemaResolver.resolveEntity(publicId, systemId);
            }
        }

        // Fall back to the parser's default behavior.
        return null;
    }

    @Override
    public String toString() {
        return "EntityResolver delegating " + XSD_SUFFIX + " to " + this.schemaResolver + " and " + DTD_SUFFIX
                + " to " + this.dtdResolver;
    }

}