defaultxmlbeandefinitionparser.java

一个关于Spring框架的示例应用程序,简单使用,可以参考.

				// just apply default to singletons, as lazy-init has no meaning for prototypes
				lazyInit = this.defaultLazyInit;
			}
			bd.setLazyInit(TRUE_VALUE.equals(lazyInit));

			return bd;
		}
		catch (ClassNotFoundException ex) {
			throw new BeanDefinitionStoreException(
					this.resource, beanName, "Bean class [" + className + "] not found", ex);
		}
		catch (NoClassDefFoundError err) {
			throw new BeanDefinitionStoreException(
					this.resource, beanName, "Class that bean class [" + className + "] depends on not found", err);
		}
	}

	/**
	 * Parse constructor argument subelements of the given bean element.
	 */
	protected ConstructorArgumentValues getConstructorArgSubElements(Element beanEle, String beanName)
			throws ClassNotFoundException {
		NodeList nl = beanEle.getChildNodes();
		ConstructorArgumentValues cargs = new ConstructorArgumentValues();
		for (int i = 0; i < nl.getLength(); i++) {
			Node node = nl.item(i);
			if (node instanceof Element && CONSTRUCTOR_ARG_ELEMENT.equals(node.getNodeName())) {
				parseConstructorArgElement((Element) node, beanName, cargs);
			}
		}
		return cargs;
	}

	/**
	 * Parse property value subelements of the given bean element.
	 */
	protected MutablePropertyValues getPropertyValueSubElements(Element beanEle, String beanName) {
		NodeList nl = beanEle.getChildNodes();
		MutablePropertyValues pvs = new MutablePropertyValues();
		for (int i = 0; i < nl.getLength(); i++) {
			Node node = nl.item(i);
			if (node instanceof Element && PROPERTY_ELEMENT.equals(node.getNodeName())) {
				parsePropertyElement((Element) node, beanName, pvs);
			}
		}
		return pvs;
	}

	/**
	 * Parse lookup-override sub elements.
	 */
	protected void getLookupOverrideSubElements(Element beanEle, String beanName, MethodOverrides overrides) {
		NodeList nl = beanEle.getChildNodes();
		for (int i = 0; i < nl.getLength(); i++) {
			Node node = nl.item(i);
			if (node instanceof Element && LOOKUP_METHOD_ELEMENT.equals(node.getNodeName())) {
				Element ele = (Element) node;
				String methodName = ele.getAttribute(NAME_ATTRIBUTE);
				String beanRef = ele.getAttribute(BEAN_ELEMENT);
				overrides.addOverride(new LookupOverride(methodName, beanRef));
			}
		}
	}

	protected void getReplacedMethodSubElements(Element beanEle, String beanName, MethodOverrides overrides) {
		NodeList nl = beanEle.getChildNodes();
		for (int i = 0; i < nl.getLength(); i++) {
			Node node = nl.item(i);
			if (node instanceof Element && REPLACED_METHOD_ELEMENT.equals(node.getNodeName())) {
				Element replacedMethodEle = (Element) node;
				String name = replacedMethodEle.getAttribute(NAME_ATTRIBUTE);
				String callback = replacedMethodEle.getAttribute(REPLACER_ATTRIBUTE);
				ReplaceOverride replaceOverride = new ReplaceOverride(name, callback);

				// Look for arg-type match elements
				NodeList argTypeNodes = replacedMethodEle.getElementsByTagName(ARG_TYPE_ELEMENT);
				for (int j = 0; j < argTypeNodes.getLength(); j++) {
					Element argTypeEle = (Element) argTypeNodes.item(j);
					replaceOverride.addTypeIdentifier(argTypeEle.getAttribute(ARG_TYPE_MATCH_ATTRIBUTE));
				}
				overrides.addOverride(replaceOverride);
			}
		}
	}

	/**
	 * Parse a constructor-arg element.
	 */
	protected void parseConstructorArgElement(Element ele, String beanName, ConstructorArgumentValues cargs)
			throws DOMException, ClassNotFoundException {
		Object val = getPropertyValue(ele, beanName, null);
		String indexAttr = ele.getAttribute(INDEX_ATTRIBUTE);
		String typeAttr = ele.getAttribute(TYPE_ATTRIBUTE);
		if (StringUtils.hasLength(indexAttr)) {
			try {
				int index = Integer.parseInt(indexAttr);
				if (index < 0) {
					throw new BeanDefinitionStoreException(this.resource, beanName, "'index' cannot be lower than 0");
				}
				if (StringUtils.hasLength(typeAttr)) {
					cargs.addIndexedArgumentValue(index, val, typeAttr);
				}
				else {
					cargs.addIndexedArgumentValue(index, val);
				}
			}
			catch (NumberFormatException ex) {
				throw new BeanDefinitionStoreException(this.resource, beanName,
						"Attribute 'index' of tag 'constructor-arg' must be an integer");
			}
		}
		else {
			if (StringUtils.hasLength(typeAttr)) {
				cargs.addGenericArgumentValue(val, typeAttr);
			}
			else {
				cargs.addGenericArgumentValue(val);
			}
		}
	}

	/**
	 * Parse a property element.
	 */
	protected void parsePropertyElement(Element ele, String beanName, MutablePropertyValues pvs) {
		String propertyName = ele.getAttribute(NAME_ATTRIBUTE);
		if (!StringUtils.hasLength(propertyName)) {
			throw new BeanDefinitionStoreException(
					this.resource, beanName, "Tag 'property' must have a 'name' attribute");
		}
		if (pvs.contains(propertyName)) {
			throw new BeanDefinitionStoreException(
					this.resource, beanName, "Multiple 'property' definitions for property '" + propertyName + "'");
		}
		Object val = getPropertyValue(ele, beanName, propertyName);
		pvs.addPropertyValue(propertyName, val);
	}

	/**
	 * Get the value of a property element. May be a list etc.
	 */
	protected Object getPropertyValue(Element ele, String beanName, String propertyName) {
		// should only have one element child: value, ref, collection
		NodeList nl = ele.getChildNodes();
		Element valueRefOrCollectionElement = null;
		for (int i = 0; i < nl.getLength(); i++) {
			if (nl.item(i) instanceof Element) {
				Element candidateEle = (Element) nl.item(i);
				if (DESCRIPTION_ELEMENT.equals(candidateEle.getTagName())) {
					// keep going: we don't use this value for now
				}
				else {
					// child element is what we're looking for
					valueRefOrCollectionElement = candidateEle;
				}
			}
		}
		if (valueRefOrCollectionElement == null) {
			String elementName = (propertyName != null) ?
					"<property> element for property '" + propertyName + "'" :
					"<constructor-arg> element";
			throw new BeanDefinitionStoreException(
					this.resource, beanName, elementName + " must have a subelement like <value> or <ref>");
		}
		return parsePropertySubelement(valueRefOrCollectionElement, beanName);
	}

	/**
	 * Parse a value, ref or collection subelement of a property element
	 * @param ele subelement of property element; we don't know which yet
	 */
	protected Object parsePropertySubelement(Element ele, String beanName) {
		if (ele.getTagName().equals(BEAN_ELEMENT)) {
			return parseBeanDefinition(ele);
		}
		else if (ele.getTagName().equals(REF_ELEMENT)) {
			// a generic reference to any name of any bean
			String beanRef = ele.getAttribute(BEAN_REF_ATTRIBUTE);
			if (!StringUtils.hasLength(beanRef)) {
				// a reference to the id of another bean in the same XML file
				beanRef = ele.getAttribute(LOCAL_REF_ATTRIBUTE);
				if (!StringUtils.hasLength(beanRef)) {
					// a reference to the id of another bean in the same XML file
					beanRef = ele.getAttribute(PARENT_REF_ATTRIBUTE);
					if (!StringUtils.hasLength(beanRef)) {
						throw new BeanDefinitionStoreException(
								this.resource, beanName, "'bean', 'local' or 'parent' is required for a reference");
					}
					return new RuntimeBeanReference(beanRef, true);
				}
			}
			return new RuntimeBeanReference(beanRef);
		}
		else if (ele.getTagName().equals(IDREF_ELEMENT)) {
			// a generic reference to any name of any bean
			String beanRef = ele.getAttribute(BEAN_REF_ATTRIBUTE);
			if (!StringUtils.hasLength(beanRef)) {
				// a reference to the id of another bean in the same XML file
				beanRef = ele.getAttribute(LOCAL_REF_ATTRIBUTE);
				if (!StringUtils.hasLength(beanRef)) {
					throw new BeanDefinitionStoreException(
							this.resource, beanName, "Either 'bean' or 'local' is required for an idref");
				}
			}
			return beanRef;
		}
		else if (ele.getTagName().equals(LIST_ELEMENT)) {
			return getList(ele, beanName);
		}
		else if (ele.getTagName().equals(SET_ELEMENT)) {
			return getSet(ele, beanName);
		}
		else if (ele.getTagName().equals(MAP_ELEMENT)) {
			return getMap(ele, beanName);
		}
		else if (ele.getTagName().equals(PROPS_ELEMENT)) {
			return getProps(ele, beanName);
		}
		else if (ele.getTagName().equals(VALUE_ELEMENT)) {
			// it's a literal value
			return getTextValue(ele, beanName);
		}
		else if (ele.getTagName().equals(NULL_ELEMENT)) {
			// it's a distinguished null value
			return null;
		}
		throw new BeanDefinitionStoreException(
				this.resource, beanName, "Unknown subelement of <property>: <" + ele.getTagName() + ">");
	}

	protected List getList(Element collectionEle, String beanName) {
		NodeList nl = collectionEle.getChildNodes();
		ManagedList list = new ManagedList(nl.getLength());
		for (int i = 0; i < nl.getLength(); i++) {
			if (nl.item(i) instanceof Element) {
				Element ele = (Element) nl.item(i);
				list.add(parsePropertySubelement(ele, beanName));
			}
		}
		return list;
	}

	protected Set getSet(Element collectionEle, String beanName) {
		NodeList nl = collectionEle.getChildNodes();
		ManagedSet set = new ManagedSet(nl.getLength());
		for (int i = 0; i < nl.getLength(); i++) {
			if (nl.item(i) instanceof Element) {
				Element ele = (Element) nl.item(i);
				set.add(parsePropertySubelement(ele, beanName));
			}
		}
		return set;
	}

	protected Map getMap(Element mapEle, String beanName) {
		List list = getChildElementsByTagName(mapEle, ENTRY_ELEMENT);
		Map map = new ManagedMap(list.size());
		for (int i = 0; i < list.size(); i++) {
			Element entryEle = (Element) list.get(i);
			String key = entryEle.getAttribute(KEY_ATTRIBUTE);
			// TODO hack: make more robust
			NodeList subEles = entryEle.getElementsByTagName("*");
			map.put(key, parsePropertySubelement((Element) subEles.item(0), beanName));
		}
		return map;
	}

	/**
	 * Don't use the horrible DOM API to get child elements:
	 * Get an element's children with a given element name
	 */
	protected List getChildElementsByTagName(Element mapEle, String elementName) {
		NodeList nl = mapEle.getChildNodes();
		List nodes = new ArrayList();
		for (int i = 0; i < nl.getLength(); i++) {
			Node n = nl.item(i);
			if (n instanceof Element && elementName.equals(n.getNodeName())) {
				nodes.add(n);
			}
		}
		return nodes;
	}

	protected Properties getProps(Element propsEle, String beanName) {
		Properties props = new Properties();
		NodeList nl = propsEle.getElementsByTagName(PROP_ELEMENT);
		for (int i = 0; i < nl.getLength(); i++) {
			Element propEle = (Element) nl.item(i);
			String key = propEle.getAttribute(KEY_ATTRIBUTE);
			// trim the text value to avoid unwanted whitespace
			// caused by typical XML formatting
			String value = getTextValue(propEle, beanName).trim();
			props.setProperty(key, value);
		}
		return props;
	}

	/**
	 * Make the horrible DOM API slightly more bearable:
	 * get the text value we know this element contains.
	 */
	protected String getTextValue(Element ele, String beanName) {
		StringBuffer value = new StringBuffer();
		NodeList nl = ele.getChildNodes();
		for (int i = 0; i < nl.getLength(); i++) {
			Node item = nl.item(i);
			if (item instanceof org.w3c.dom.CharacterData) {
				if (!(item instanceof Comment)) {
					value.append(item.getNodeValue());
				}
			}
			else {
				throw new BeanDefinitionStoreException(
						this.resource, beanName,
						"<value> element is just allowed to have text and comment nodes, not: " + item.getClass().getName());
			}
		}
		return value.toString();
	}

	protected int getDependencyCheck(String att) {
		int dependencyCheckCode = AbstractBeanDefinition.DEPENDENCY_CHECK_NONE;
		if (DEPENDENCY_CHECK_ALL_ATTRIBUTE_VALUE.equals(att)) {
			dependencyCheckCode = AbstractBeanDefinition.DEPENDENCY_CHECK_ALL;
		}
		else if (DEPENDENCY_CHECK_SIMPLE_ATTRIBUTE_VALUE.equals(att)) {
			dependencyCheckCode = AbstractBeanDefinition.DEPENDENCY_CHECK_SIMPLE;
		}
		else if (DEPENDENCY_CHECK_OBJECTS_ATTRIBUTE_VALUE.equals(att)) {
			dependencyCheckCode = AbstractBeanDefinition.DEPENDENCY_CHECK_OBJECTS;
		}
		// else leave default value
		return dependencyCheckCode;
	}

	protected int getAutowireMode(String att) {
		int autowire = AbstractBeanDefinition.AUTOWIRE_NO;
		if (AUTOWIRE_BY_NAME_VALUE.equals(att)) {
			autowire = AbstractBeanDefinition.AUTOWIRE_BY_NAME;
		}
		else if (AUTOWIRE_BY_TYPE_VALUE.equals(att)) {
			autowire = AbstractBeanDefinition.AUTOWIRE_BY_TYPE;
		}
		else if (AUTOWIRE_CONSTRUCTOR_VALUE.equals(att)) {
			autowire = AbstractBeanDefinition.AUTOWIRE_CONSTRUCTOR;
		}
		else if (AUTOWIRE_AUTODETECT_VALUE.equals(att)) {
			autowire = AbstractBeanDefinition.AUTOWIRE_AUTODETECT;
		}
		// else leave default value
		return autowire;
	}

}