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Spring Framework example source code file (XmlBeanDefinitionReader.java)

This example Spring Framework source code file (XmlBeanDefinitionReader.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Spring Framework tags/keywords

beandefinitiondocumentreader, beandefinitionstoreexception, beandefinitionstoreexception, dom, inputsource, inputstream, io, ioexception, ioexception, parser, resource, sax, util, validation_auto, validation_auto, xml, xml, xmlbeandefinitionparser, xmlbeandefinitionreader

The Spring Framework XmlBeanDefinitionReader.java source code

/*
 * Copyright 2002-2008 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.beans.factory.xml;

import java.io.IOException;
import java.io.InputStream;
import java.util.HashSet;
import java.util.Set;

import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;
import org.xml.sax.EntityResolver;
import org.xml.sax.ErrorHandler;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;

import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.BeanDefinitionStoreException;
import org.springframework.beans.factory.parsing.EmptyReaderEventListener;
import org.springframework.beans.factory.parsing.FailFastProblemReporter;
import org.springframework.beans.factory.parsing.NullSourceExtractor;
import org.springframework.beans.factory.parsing.ProblemReporter;
import org.springframework.beans.factory.parsing.ReaderEventListener;
import org.springframework.beans.factory.parsing.SourceExtractor;
import org.springframework.beans.factory.support.AbstractBeanDefinitionReader;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.core.Constants;
import org.springframework.core.NamedThreadLocal;
import org.springframework.core.io.DescriptiveResource;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;
import org.springframework.core.io.support.EncodedResource;
import org.springframework.util.Assert;
import org.springframework.util.xml.SimpleSaxErrorHandler;
import org.springframework.util.xml.XmlValidationModeDetector;

/**
 * Bean definition reader for XML bean definitions.
 * Delegates the actual XML document reading to an implementation
 * of the {@link BeanDefinitionDocumentReader} interface.
 *
 * <p>Typically applied to a
 * {@link org.springframework.beans.factory.support.DefaultListableBeanFactory}
 * or a {@link org.springframework.context.support.GenericApplicationContext}.
 *
 * <p>This class loads a DOM document and applies the BeanDefinitionDocumentReader to it.
 * The document reader will register each bean definition with the given bean factory,
 * talking to the latter's implementation of the
 * {@link org.springframework.beans.factory.support.BeanDefinitionRegistry} interface.
 *
 * @author Juergen Hoeller
 * @author Rob Harrop
 * @since 26.11.2003
 * @see #setDocumentReaderClass
 * @see BeanDefinitionDocumentReader
 * @see DefaultBeanDefinitionDocumentReader
 * @see BeanDefinitionRegistry
 * @see org.springframework.beans.factory.support.DefaultListableBeanFactory
 * @see org.springframework.context.support.GenericApplicationContext
 */
public class XmlBeanDefinitionReader extends AbstractBeanDefinitionReader {

	/**
	 * Indicates that the validation should be disabled.
	 */
	public static final int VALIDATION_NONE = XmlValidationModeDetector.VALIDATION_NONE;

	/**
	 * Indicates that the validation mode should be detected automatically.
	 */
	public static final int VALIDATION_AUTO = XmlValidationModeDetector.VALIDATION_AUTO;

	/**
	 * Indicates that DTD validation should be used.
	 */
	public static final int VALIDATION_DTD = XmlValidationModeDetector.VALIDATION_DTD;

	/**
	 * Indicates that XSD validation should be used.
	 */
	public static final int VALIDATION_XSD = XmlValidationModeDetector.VALIDATION_XSD;


	/** Constants instance for this class */
	private static final Constants constants = new Constants(XmlBeanDefinitionReader.class);

	private boolean namespaceAware;

	private int validationMode = VALIDATION_AUTO;

	private Class parserClass;

	private Class documentReaderClass = DefaultBeanDefinitionDocumentReader.class;

	private ProblemReporter problemReporter = new FailFastProblemReporter();

	private ReaderEventListener eventListener = new EmptyReaderEventListener();

	private SourceExtractor sourceExtractor = new NullSourceExtractor();

	private NamespaceHandlerResolver namespaceHandlerResolver;

	private DocumentLoader documentLoader = new DefaultDocumentLoader();

	private EntityResolver entityResolver;

	private ErrorHandler errorHandler = new SimpleSaxErrorHandler(logger);

	private final XmlValidationModeDetector validationModeDetector = new XmlValidationModeDetector();

	private final ThreadLocal resourcesCurrentlyBeingLoaded =
			new NamedThreadLocal("XML bean definition resources currently being loaded");


	/**
	 * Create new XmlBeanDefinitionReader for the given bean factory.
	 * @param registry the BeanFactory to load bean definitions into,
	 * in the form of a BeanDefinitionRegistry
	 */
	public XmlBeanDefinitionReader(BeanDefinitionRegistry registry) {
		super(registry);
	}


	/**
	 * Set whether or not the XML parser should be XML namespace aware.
	 * Default is "false".
	 */
	public void setNamespaceAware(boolean namespaceAware) {
		this.namespaceAware = namespaceAware;
	}

	/**
	 * Return whether or not the XML parser should be XML namespace aware.
	 */
	public boolean isNamespaceAware() {
		return this.namespaceAware;
	}

	/**
	 * Set if the XML parser should validate the document and thus enforce a DTD.
	 * @deprecated as of Spring 2.0: superseded by "validationMode"
	 * @see #setValidationMode
	 */
	public void setValidating(boolean validating) {
		this.validationMode = (validating ? VALIDATION_AUTO : VALIDATION_NONE);
	}

	/**
	 * Set the validation mode to use by name. Defaults to {@link #VALIDATION_AUTO}.
	 */
	public void setValidationModeName(String validationModeName) {
		setValidationMode(constants.asNumber(validationModeName).intValue());
	}

	/**
	 * Set the validation mode to use. Defaults to {@link #VALIDATION_AUTO}.
	 */
	public void setValidationMode(int validationMode) {
		this.validationMode = validationMode;
	}

	/**
	 * Return the validation mode to use.
	 */
	public int getValidationMode() {
		return this.validationMode;
	}

	/**
	 * Specify which {@link org.springframework.beans.factory.parsing.ProblemReporter} to use. Default implementation is
	 * {@link org.springframework.beans.factory.parsing.FailFastProblemReporter} which exhibits fail fast behaviour. External tools
	 * can provide an alternative implementation that collates errors and warnings for
	 * display in the tool UI.
	 */
	public void setProblemReporter(ProblemReporter problemReporter) {
		this.problemReporter = (problemReporter != null ? problemReporter : new FailFastProblemReporter());
	}

	/**
	 * Specify which {@link ReaderEventListener} to use. Default implementation is
	 * EmptyReaderEventListener which discards every event notification. External tools
	 * can provide an alternative implementation to monitor the components being registered
	 * in the BeanFactory.
	 */
	public void setEventListener(ReaderEventListener eventListener) {
		this.eventListener = (eventListener != null ? eventListener : new EmptyReaderEventListener());
	}

	/**
	 * Specify the {@link SourceExtractor} to use. The default implementation is
	 * {@link NullSourceExtractor} which simply returns <code>null as the source object.
	 * This means that during normal runtime execution no additional source metadata is attached
	 * to the bean configuration metadata.
	 */
	public void setSourceExtractor(SourceExtractor sourceExtractor) {
		this.sourceExtractor = (sourceExtractor != null ? sourceExtractor : new NullSourceExtractor());
	}

	/**
	 * Specify the {@link NamespaceHandlerResolver} to use. If none is specified a default
	 * instance will be created by {@link #createDefaultNamespaceHandlerResolver()}.
	 */
	public void setNamespaceHandlerResolver(NamespaceHandlerResolver namespaceHandlerResolver) {
		this.namespaceHandlerResolver = namespaceHandlerResolver;
	}

	/**
	 * Specify the {@link DocumentLoader} to use. The default implementation is
	 * {@link DefaultDocumentLoader} which loads {@link Document} instances using JAXP.
	 */
	public void setDocumentLoader(DocumentLoader documentLoader) {
		this.documentLoader = (documentLoader != null ? documentLoader : new DefaultDocumentLoader());
	}

	/**
	 * Set a SAX entity resolver to be used for parsing. By default,
	 * BeansDtdResolver will be used. Can be overridden for custom entity
	 * resolution, for example relative to some specific base path.
	 * @see BeansDtdResolver
	 */
	public void setEntityResolver(EntityResolver entityResolver) {
		this.entityResolver = entityResolver;
	}

	/**
	 * Return the EntityResolver to use, building a default resolver
	 * if none specified.
	 */
	protected EntityResolver getEntityResolver() {
		if (this.entityResolver == null) {
			// Determine default EntityResolver to use.
			ResourceLoader resourceLoader = getResourceLoader();
			if (resourceLoader != null) {
				this.entityResolver = new ResourceEntityResolver(resourceLoader);
			}
			else {
				this.entityResolver = new DelegatingEntityResolver(getBeanClassLoader());
			}
		}
		return this.entityResolver;
	}

	/**
	 * Set an implementation of the <code>org.xml.sax.ErrorHandler
	 * interface for custom handling of XML parsing errors and warnings.
	 * <p>If not set, a default SimpleSaxErrorHandler is used that simply
	 * logs warnings using the logger instance of the view class,
	 * and rethrows errors to discontinue the XML transformation.
	 * @see SimpleSaxErrorHandler
	 */
	public void setErrorHandler(ErrorHandler errorHandler) {
		this.errorHandler = errorHandler;
	}

	/**
	 * Set the XmlBeanDefinitionParser implementation to use,
	 * responsible for the actual parsing of XML bean definitions.
	 * @deprecated as of Spring 2.0: superseded by "documentReaderClass"
	 * @see #setDocumentReaderClass
	 * @see XmlBeanDefinitionParser
	 */
	public void setParserClass(Class parserClass) {
		if (this.parserClass == null || !XmlBeanDefinitionParser.class.isAssignableFrom(parserClass)) {
			throw new IllegalArgumentException("'parserClass' must be an XmlBeanDefinitionParser");
		}
		this.parserClass = parserClass;
	}

	/**
	 * Specify the BeanDefinitionDocumentReader implementation to use,
	 * responsible for the actual reading of the XML bean definition document.
	 * <p>Default is DefaultBeanDefinitionDocumentReader.
	 * @param documentReaderClass the desired BeanDefinitionDocumentReader implementation class
	 * @see BeanDefinitionDocumentReader
	 * @see DefaultBeanDefinitionDocumentReader
	 */
	public void setDocumentReaderClass(Class documentReaderClass) {
		if (documentReaderClass == null || !BeanDefinitionDocumentReader.class.isAssignableFrom(documentReaderClass)) {
			throw new IllegalArgumentException(
					"documentReaderClass must be an implementation of the BeanDefinitionDocumentReader interface");
		}
		this.documentReaderClass = documentReaderClass;
	}


	/**
	 * Load bean definitions from the specified XML file.
	 * @param resource the resource descriptor for the XML file
	 * @return the number of bean definitions found
	 * @throws BeanDefinitionStoreException in case of loading or parsing errors
	 */
	public int loadBeanDefinitions(Resource resource) throws BeanDefinitionStoreException {
		return loadBeanDefinitions(new EncodedResource(resource));
	}

	/**
	 * Load bean definitions from the specified XML file.
	 * @param encodedResource the resource descriptor for the XML file,
	 * allowing to specify an encoding to use for parsing the file
	 * @return the number of bean definitions found
	 * @throws BeanDefinitionStoreException in case of loading or parsing errors
	 */
	public int loadBeanDefinitions(EncodedResource encodedResource) throws BeanDefinitionStoreException {
		Assert.notNull(encodedResource, "EncodedResource must not be null");
		if (logger.isInfoEnabled()) {
			logger.info("Loading XML bean definitions from " + encodedResource.getResource());
		}

		Set currentResources = (Set) this.resourcesCurrentlyBeingLoaded.get();
		if (currentResources == null) {
			currentResources = new HashSet(4);
			this.resourcesCurrentlyBeingLoaded.set(currentResources);
		}
		if (!currentResources.add(encodedResource)) {
			throw new BeanDefinitionStoreException(
					"Detected recursive loading of " + encodedResource + " - check your import definitions!");
		}
		try {
			InputStream inputStream = encodedResource.getResource().getInputStream();
			try {
				InputSource inputSource = new InputSource(inputStream);
				if (encodedResource.getEncoding() != null) {
					inputSource.setEncoding(encodedResource.getEncoding());
				}
				return doLoadBeanDefinitions(inputSource, encodedResource.getResource());
			}
			finally {
				inputStream.close();
			}
		}
		catch (IOException ex) {
			throw new BeanDefinitionStoreException(
					"IOException parsing XML document from " + encodedResource.getResource(), ex);
		}
		finally {
			currentResources.remove(encodedResource);
			if (currentResources.isEmpty()) {
				this.resourcesCurrentlyBeingLoaded.set(null);
			}
		}
	}

	/**
	 * Load bean definitions from the specified XML file.
	 * @param inputSource the SAX InputSource to read from
	 * @return the number of bean definitions found
	 * @throws BeanDefinitionStoreException in case of loading or parsing errors
	 */
	public int loadBeanDefinitions(InputSource inputSource) throws BeanDefinitionStoreException {
		return loadBeanDefinitions(inputSource, "resource loaded through SAX InputSource");
	}

	/**
	 * Load bean definitions from the specified XML file.
	 * @param inputSource the SAX InputSource to read from
	 * @param resourceDescription a description of the resource
	 * (can be <code>null or empty)
	 * @return the number of bean definitions found
	 * @throws BeanDefinitionStoreException in case of loading or parsing errors
	 */
	public int loadBeanDefinitions(InputSource inputSource, String resourceDescription)
			throws BeanDefinitionStoreException {

		return doLoadBeanDefinitions(inputSource, new DescriptiveResource(resourceDescription));
	}


	/**
	 * Actually load bean definitions from the specified XML file.
	 * @param inputSource the SAX InputSource to read from
	 * @param resource the resource descriptor for the XML file
	 * @return the number of bean definitions found
	 * @throws BeanDefinitionStoreException in case of loading or parsing errors
	 */
	protected int doLoadBeanDefinitions(InputSource inputSource, Resource resource)
			throws BeanDefinitionStoreException {
		try {
			int validationMode = getValidationModeForResource(resource);
			Document doc = this.documentLoader.loadDocument(
					inputSource, getEntityResolver(), this.errorHandler, validationMode, isNamespaceAware());
			return registerBeanDefinitions(doc, resource);
		}
		catch (BeanDefinitionStoreException ex) {
			throw ex;
		}
		catch (SAXParseException ex) {
			throw new XmlBeanDefinitionStoreException(resource.getDescription(),
					"Line " + ex.getLineNumber() + " in XML document from " + resource + " is invalid", ex);
		}
		catch (SAXException ex) {
			throw new XmlBeanDefinitionStoreException(resource.getDescription(),
					"XML document from " + resource + " is invalid", ex);
		}
		catch (ParserConfigurationException ex) {
			throw new BeanDefinitionStoreException(resource.getDescription(),
					"Parser configuration exception parsing XML from " + resource, ex);
		}
		catch (IOException ex) {
			throw new BeanDefinitionStoreException(resource.getDescription(),
					"IOException parsing XML document from " + resource, ex);
		}
		catch (Throwable ex) {
			throw new BeanDefinitionStoreException(resource.getDescription(),
					"Unexpected exception parsing XML document from " + resource, ex);
		}
	}


	/**
	 * Gets the validation mode for the specified {@link Resource}. If no explicit
	 * validation mode has been configured then the validation mode is
	 * {@link #detectValidationMode detected}.
	 * <p>Override this method if you would like full control over the validation
	 * mode, even when something other than {@link #VALIDATION_AUTO} was set.
	 */
	protected int getValidationModeForResource(Resource resource) {
		int validationModeToUse = getValidationMode();
		if (validationModeToUse != VALIDATION_AUTO) {
			return validationModeToUse;
		}
		int detectedMode = detectValidationMode(resource);
		if (detectedMode != VALIDATION_AUTO) {
			return detectedMode;
		}
		// Hmm, we didn't get a clear indication... Let's assume XSD,
		// since apparently no DTD declaration has been found up until
		// detection stopped (before finding the document's root tag).
		return VALIDATION_XSD;
	}

	/**
	 * Detects which kind of validation to perform on the XML file identified
	 * by the supplied {@link Resource}. If the file has a <code>DOCTYPE
	 * definition then DTD validation is used otherwise XSD validation is assumed.
	 * <p>Override this method if you would like to customize resolution
	 * of the {@link #VALIDATION_AUTO} mode.
	 */
	protected int detectValidationMode(Resource resource) {
		if (resource.isOpen()) {
			throw new BeanDefinitionStoreException(
					"Passed-in Resource [" + resource + "] contains an open stream: " +
					"cannot determine validation mode automatically. Either pass in a Resource " +
					"that is able to create fresh streams, or explicitly specify the validationMode " +
					"on your XmlBeanDefinitionReader instance.");
		}

		InputStream inputStream;
		try {
			inputStream = resource.getInputStream();
		}
		catch (IOException ex) {
			throw new BeanDefinitionStoreException(
					"Unable to determine validation mode for [" + resource + "]: cannot open InputStream. " +
					"Did you attempt to load directly from a SAX InputSource without specifying the " +
					"validationMode on your XmlBeanDefinitionReader instance?", ex);
		}

		try {
			return this.validationModeDetector.detectValidationMode(inputStream);
		}
		catch (IOException ex) {
			throw new BeanDefinitionStoreException("Unable to determine validation mode for [" +
					resource + "]: an error occurred whilst reading from the InputStream.", ex);
		}
	}

	/**
	 * Register the bean definitions contained in the given DOM document.
	 * Called by <code>loadBeanDefinitions.
	 * <p>Creates a new instance of the parser class and invokes
	 * <code>registerBeanDefinitions on it.
	 * @param doc the DOM document
	 * @param resource the resource descriptor (for context information)
	 * @return the number of bean definitions found
	 * @throws BeanDefinitionStoreException in case of parsing errors
	 * @see #loadBeanDefinitions
	 * @see #setDocumentReaderClass
	 * @see BeanDefinitionDocumentReader#registerBeanDefinitions
	 */
	public int registerBeanDefinitions(Document doc, Resource resource) throws BeanDefinitionStoreException {
		// Support old XmlBeanDefinitionParser SPI for backwards-compatibility.
		if (this.parserClass != null) {
			XmlBeanDefinitionParser parser =
					(XmlBeanDefinitionParser) BeanUtils.instantiateClass(this.parserClass);
			return parser.registerBeanDefinitions(this, doc, resource);
		}
		// Read document based on new BeanDefinitionDocumentReader SPI.
		BeanDefinitionDocumentReader documentReader = createBeanDefinitionDocumentReader();
		int countBefore = getRegistry().getBeanDefinitionCount();
		documentReader.registerBeanDefinitions(doc, createReaderContext(resource));
		return getRegistry().getBeanDefinitionCount() - countBefore;
	}

	/**
	 * Create the {@link BeanDefinitionDocumentReader} to use for actually
	 * reading bean definitions from an XML document.
	 * <p>Default implementation instantiates the specified "documentReaderClass".
	 * @see #setDocumentReaderClass
	 */
	protected BeanDefinitionDocumentReader createBeanDefinitionDocumentReader() {
		return (BeanDefinitionDocumentReader) BeanUtils.instantiateClass(this.documentReaderClass);
	}

	/**
	 * Create the {@link XmlReaderContext} to pass over to the document reader.
	 */
	protected XmlReaderContext createReaderContext(Resource resource) {
		if (this.namespaceHandlerResolver == null) {
			this.namespaceHandlerResolver = createDefaultNamespaceHandlerResolver();
		}
		return new XmlReaderContext(resource, this.problemReporter, this.eventListener,
				this.sourceExtractor, this, this.namespaceHandlerResolver);
	}

	/**
	 * Create the default implementation of {@link NamespaceHandlerResolver} used if none is specified.
	 * Default implementation returns an instance of {@link DefaultNamespaceHandlerResolver}.
	 */
	protected NamespaceHandlerResolver createDefaultNamespaceHandlerResolver() {
		return new DefaultNamespaceHandlerResolver(getResourceLoader().getClassLoader());
	}

}

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