对dom树的解析封装成应有的数据结构--BeanDefinitionParserDelegate
拒绝就业的后果是什么？如果在上山下乡的时候，必定被居委会大妈每天烦扰了，然后禁不住死缠烂打就上山下乡了，这个时代是相对幸运的，至少政策没有那么严苛，那么我今天就进入最喜欢的一个类的解析了，所有解释型的语言都有一个队DOM树的PASER，Spring中的PASER，是这个类：BeanDefinitionParserDelegate。
public static final String BEANS_NAMESPACE_URI = "http://www.springframework.org/schema/beans"; public static final String MULTI_VALUE_ATTRIBUTE_DELIMITERS = ",; ";
第一个属性石Spring框架的命名空间URI，http://www.springframework.org/schema/beans。点击开网址，会看到一些关于Spring的xsd文件，是一种解析规则，看来服务器还是要和Spring的官方服务器进行对话的。
第二个属性定义了一个Value属性的分隔符。
/** @deprecated as of Spring 3.1 in favor of {@link #MULTI_VALUE_ATTRIBUTE_DELIMITERS} */
public static final String BEAN_NAME_DELIMITERS = MULTI_VALUE_ATTRIBUTE_DELIMITERS;
被弃用的属性。
/** * Value of a T/F attribute that represents true. * Anything else represents false. Case seNsItive. */ public static final String TRUE_VALUE = "true"; public static final String FALSE_VALUE = "false"; public static final String DEFAULT_VALUE = "default"; public static final String DESCRIPTION_ELEMENT = "description"; public static final String AUTOWIRE_NO_VALUE = "no"; public static final String AUTOWIRE_BY_NAME_VALUE = "byName"; public static final String AUTOWIRE_BY_TYPE_VALUE = "byType"; public static final String AUTOWIRE_CONSTRUCTOR_VALUE = "constructor"; public static final String AUTOWIRE_AUTODETECT_VALUE = "autodetect"; public static final String DEPENDENCY_CHECK_ALL_ATTRIBUTE_VALUE = "all"; public static final String DEPENDENCY_CHECK_SIMPLE_ATTRIBUTE_VALUE = "simple"; public static final String DEPENDENCY_CHECK_OBJECTS_ATTRIBUTE_VALUE = "objects"; public static final String NAME_ATTRIBUTE = "name"; public static final String BEAN_ELEMENT = "bean"; public static final String META_ELEMENT = "meta"; public static final String ID_ATTRIBUTE = "id"; public static final String PARENT_ATTRIBUTE = "parent"; public static final String CLASS_ATTRIBUTE = "class"; public static final String ABSTRACT_ATTRIBUTE = "abstract"; public static final String SCOPE_ATTRIBUTE = "scope"; public static final String SINGLETON_ATTRIBUTE = "singleton"; public static final String LAZY_INIT_ATTRIBUTE = "lazy-init"; public static final String AUTOWIRE_ATTRIBUTE = "autowire"; public static final String AUTOWIRE_CANDIDATE_ATTRIBUTE = "autowire-candidate"; public static final String PRIMARY_ATTRIBUTE = "primary"; public static final String DEPENDENCY_CHECK_ATTRIBUTE = "dependency-check"; public static final String DEPENDS_ON_ATTRIBUTE = "depends-on"; public static final String INIT_METHOD_ATTRIBUTE = "init-method"; public static final String DESTROY_METHOD_ATTRIBUTE = "destroy-method"; public static final String FACTORY_METHOD_ATTRIBUTE = "factory-method"; public static final String FACTORY_BEAN_ATTRIBUTE = "factory-bean"; public static final String CONSTRUCTOR_ARG_ELEMENT = "constructor-arg"; public static final String INDEX_ATTRIBUTE = "index"; public static final String TYPE_ATTRIBUTE = "type"; public static final String VALUE_TYPE_ATTRIBUTE = "value-type"; public static final String KEY_TYPE_ATTRIBUTE = "key-type"; public static final String PROPERTY_ELEMENT = "property"; public static final String REF_ATTRIBUTE = "ref"; public static final String VALUE_ATTRIBUTE = "value"; public static final String LOOKUP_METHOD_ELEMENT = "lookup-method"; public static final String REPLACED_METHOD_ELEMENT = "replaced-method"; public static final String REPLACER_ATTRIBUTE = "replacer"; public static final String ARG_TYPE_ELEMENT = "arg-type"; public static final String ARG_TYPE_MATCH_ATTRIBUTE = "match"; public static final String REF_ELEMENT = "ref"; public static final String IDREF_ELEMENT = "idref"; public static final String BEAN_REF_ATTRIBUTE = "bean"; public static final String LOCAL_REF_ATTRIBUTE = "local"; public static final String PARENT_REF_ATTRIBUTE = "parent"; public static final String VALUE_ELEMENT = "value"; public static final String NULL_ELEMENT = "null"; public static final String ARRAY_ELEMENT = "array"; public static final String LIST_ELEMENT = "list"; public static final String SET_ELEMENT = "set"; public static final String MAP_ELEMENT = "map"; public static final String ENTRY_ELEMENT = "entry"; public static final String KEY_ELEMENT = "key"; public static final String KEY_ATTRIBUTE = "key"; public static final String KEY_REF_ATTRIBUTE = "key-ref"; public static final String VALUE_REF_ATTRIBUTE = "value-ref"; public static final String PROPS_ELEMENT = "props"; public static final String PROP_ELEMENT = "prop"; public static final String MERGE_ATTRIBUTE = "merge"; public static final String QUALIFIER_ELEMENT = "qualifier"; public static final String QUALIFIER_ATTRIBUTE_ELEMENT = "attribute"; public static final String DEFAULT_LAZY_INIT_ATTRIBUTE = "default-lazy-init"; public static final String DEFAULT_MERGE_ATTRIBUTE = "default-merge"; public static final String DEFAULT_AUTOWIRE_ATTRIBUTE = "default-autowire"; public static final String DEFAULT_DEPENDENCY_CHECK_ATTRIBUTE = "default-dependency-check"; public static final String DEFAULT_AUTOWIRE_CANDIDATES_ATTRIBUTE = "default-autowire-candidates"; public static final String DEFAULT_INIT_METHOD_ATTRIBUTE = "default-init-method"; public static final String DEFAULT_DESTROY_METHOD_ATTRIBUTE = "default-destroy-method";
终于见面了，这些在xml中配置的属性。
protected final Log logger = LogFactory.getLog(getClass()); private final XmlReaderContext readerContext; private final DocumentDefaultsDefinition defaults = new DocumentDefaultsDefinition(); private final ParseState parseState = new ParseState(); private Environment environment;
日志，XMLrEADERcONTEXT,DocumentDefaultsDefinition,ParseState,Environment。
/** * Stores all used bean names so we can enforce uniqueness on a per * beans-element basis. Duplicate bean ids/names may not exist within the * same level of beans element nesting, but may be duplicated across levels. */ private final Set<String> usedNames = new HashSet<String>();
让属性名字唯一。
/**
* Create a new BeanDefinitionParserDelegate associated with the
* supplied {@link XmlReaderContext} and {@link Environment}.
*/
public BeanDefinitionParserDelegate(XmlReaderContext readerContext, Environment environment) {
Assert.notNull(readerContext, "XmlReaderContext must not be null");
Assert.notNull(readerContext, "Environment must not be null");
this.readerContext = readerContext;
this.environment = environment;
}
初始化。
/**
* Create a new BeanDefinitionParserDelegate associated with the
* supplied {@link XmlReaderContext} and a new {@link StandardEnvironment}.
* @deprecated since Spring 3.1 in favor of
* {@link #BeanDefinitionParserDelegate(XmlReaderContext, Environment)}
*/
@Deprecated
public BeanDefinitionParserDelegate(XmlReaderContext readerContext) {
this(readerContext, new StandardEnvironment());
}
默认的环境初始化。
/**
* Get the {@link XmlReaderContext} associated with this helper instance.
*/
public final XmlReaderContext getReaderContext() {
return this.readerContext;
}
/**
* Get the {@link Environment} associated with this helper instance.
*/
public final Environment getEnvironment() {
return this.environment;
}
get到。
/**
* Invoke the {@link org.springframework.beans.factory.parsing.SourceExtractor} to pull the
* source metadata from the supplied {@link Element}.
*/
protected Object extractSource(Element ele) {
return this.readerContext.extractSource(ele);
}
从封装好的Element中提取Source。
/**
* Report an error with the given message for the given source element.
*/
protected void error(String message, Node source) {
this.readerContext.error(message, source, this.parseState.snapshot());
}
/**
* Report an error with the given message for the given source element.
*/
protected void error(String message, Element source) {
this.readerContext.error(message, source, this.parseState.snapshot());
}
/**
* Report an error with the given message for the given source element.
*/
protected void error(String message, Element source, Throwable cause) {
this.readerContext.error(message, source, this.parseState.snapshot(), cause);
}
弹射错误。
/**
* Initialize the default lazy-init, autowire, dependency check settings,
* init-method, destroy-method and merge settings. Support nested 'beans'
* element use cases by falling back to the given parent in case the
* defaults are not explicitly set locally.
* @see #populateDefaults(DocumentDefaultsDefinition, DocumentDefaultsDefinition, org.w3c.dom.Element)
* @see #getDefaults()
*/
public void initDefaults(Element root, BeanDefinitionParserDelegate parent) {
populateDefaults(this.defaults, (parent != null ? parent.defaults : null), root);
this.readerContext.fireDefaultsRegistered(this.defaults);
}
/**
* Initialize the default settings assuming a {@code null} parent delegate.
* @deprecated in Spring 3.1 in favor of
* {@link #initDefaults(Element, BeanDefinitionParserDelegate)}
*/
public void initDefaults(Element root) {
initDefaults(root, null);
}
初始化所有。
/**
* Populate the given DocumentDefaultsDefinition instance with the default lazy-init,
* autowire, dependency check settings, init-method, destroy-method and merge settings.
* Support nested 'beans' element use cases by falling back to
* <literal>parentDefaults</literal> in case the defaults are not explicitly set
* locally.
* @param defaults the defaults to populate
* @param defaults the parent BeanDefinitionParserDelegate (if any) defaults to fall back to
* @param root the root element of the current bean definition document (or nested beans element)
*/
protected void populateDefaults(DocumentDefaultsDefinition defaults, DocumentDefaultsDefinition parentDefaults, Element root) {
String lazyInit = root.getAttribute(DEFAULT_LAZY_INIT_ATTRIBUTE);
if (DEFAULT_VALUE.equals(lazyInit)) {
lazyInit = parentDefaults != null ? parentDefaults.getLazyInit() : FALSE_VALUE;
}
defaults.setLazyInit(lazyInit);
String merge = root.getAttribute(DEFAULT_MERGE_ATTRIBUTE);
if (DEFAULT_VALUE.equals(merge)) {
merge = parentDefaults != null ? parentDefaults.getMerge() : FALSE_VALUE;
}
defaults.setMerge(merge);
String autowire = root.getAttribute(DEFAULT_AUTOWIRE_ATTRIBUTE);
if (DEFAULT_VALUE.equals(autowire)) {
autowire = parentDefaults != null ? parentDefaults.getAutowire() : AUTOWIRE_NO_VALUE;
}
defaults.setAutowire(autowire);
// don't fall back to parentDefaults for dependency-check as it's no
// longer supported in <beans> as of 3.0. Therefore, no nested <beans>
// would ever need to fall back to it.
defaults.setDependencyCheck(root.getAttribute(DEFAULT_DEPENDENCY_CHECK_ATTRIBUTE));
if (root.hasAttribute(DEFAULT_AUTOWIRE_CANDIDATES_ATTRIBUTE)) {
defaults.setAutowireCandidates(root.getAttribute(DEFAULT_AUTOWIRE_CANDIDATES_ATTRIBUTE));
}
else if (parentDefaults != null) {
defaults.setAutowireCandidates(parentDefaults.getAutowireCandidates());
}
if (root.hasAttribute(DEFAULT_INIT_METHOD_ATTRIBUTE)) {
defaults.setInitMethod(root.getAttribute(DEFAULT_INIT_METHOD_ATTRIBUTE));
}
else if (parentDefaults != null) {
defaults.setInitMethod(parentDefaults.getInitMethod());
}
if (root.hasAttribute(DEFAULT_DESTROY_METHOD_ATTRIBUTE)) {
defaults.setDestroyMethod(root.getAttribute(DEFAULT_DESTROY_METHOD_ATTRIBUTE));
}
else if (parentDefaults != null) {
defaults.setDestroyMethod(parentDefaults.getDestroyMethod());
}
defaults.setSource(this.readerContext.extractSource(root));
}
主要是用来配置属性，原则是没有配置检测属性就从父类的DocumentDefaultsDefinition取得。
/**
* Return the defaults definition object, or <code>null</code> if the
* defaults have been initialized yet.
*/
public DocumentDefaultsDefinition getDefaults() {
return this.defaults;
}
取得默认的DocumentDefaultsDefinition。
/**
* Return the default settings for bean definitions as indicated within
* the attributes of the top-level <code><beans/></code> element.
*/
public BeanDefinitionDefaults getBeanDefinitionDefaults() {
BeanDefinitionDefaults bdd = new BeanDefinitionDefaults();
bdd.setLazyInit("TRUE".equalsIgnoreCase(this.defaults.getLazyInit()));
bdd.setDependencyCheck(this.getDependencyCheck(DEFAULT_VALUE));
bdd.setAutowireMode(this.getAutowireMode(DEFAULT_VALUE));
bdd.setInitMethodName(this.defaults.getInitMethod());
bdd.setDestroyMethodName(this.defaults.getDestroyMethod());
return bdd;
}
默认的Beandefinition。
/**
* Parses the supplied <code><bean></code> element. May return <code>null</code>
* if there were errors during parse. Errors are reported to the
* {@link org.springframework.beans.factory.parsing.ProblemReporter}.
*/
public BeanDefinitionHolder parseBeanDefinitionElement(Element ele) {
return parseBeanDefinitionElement(ele, null);
}
转换BeanDefinition，调用下面的方法。
/**
* Parses the supplied <code><bean></code> element. May return <code>null</code>
* if there were errors during parse. Errors are reported to the
* {@link org.springframework.beans.factory.parsing.ProblemReporter}.
*/
public BeanDefinitionHolder parseBeanDefinitionElement(Element ele, BeanDefinition containingBean) {
String id = ele.getAttribute(ID_ATTRIBUTE);
String nameAttr = ele.getAttribute(NAME_ATTRIBUTE);
List<String> aliases = new ArrayList<String>();
if (StringUtils.hasLength(nameAttr)) {
String[] nameArr = StringUtils.tokenizeToStringArray(nameAttr, MULTI_VALUE_ATTRIBUTE_DELIMITERS);
aliases.addAll(Arrays.asList(nameArr));
}
String beanName = id;
if (!StringUtils.hasText(beanName) && !aliases.isEmpty()) {
beanName = aliases.remove(0);
if (logger.isDebugEnabled()) {
logger.debug("No XML 'id' specified - using '" + beanName +
"' as bean name and " + aliases + " as aliases");
}
}
if (containingBean == null) {
checkNameUniqueness(beanName, aliases, ele);
}
AbstractBeanDefinition beanDefinition = parseBeanDefinitionElement(ele, beanName, containingBean);
if (beanDefinition != null) {
if (!StringUtils.hasText(beanName)) {
try {
if (containingBean != null) {
beanName = BeanDefinitionReaderUtils.generateBeanName(
beanDefinition, this.readerContext.getRegistry(), true);
}
else {
beanName = this.readerContext.generateBeanName(beanDefinition);
// Register an alias for the plain bean class name, if still possible,
// if the generator returned the class name plus a suffix.
// This is expected for Spring 1.2/2.0 backwards compatibility.
String beanClassName = beanDefinition.getBeanClassName();
if (beanClassName != null &&
beanName.startsWith(beanClassName) && beanName.length() > beanClassName.length() &&
!this.readerContext.getRegistry().isBeanNameInUse(beanClassName)) {
aliases.add(beanClassName);
}
}
if (logger.isDebugEnabled()) {
logger.debug("Neither XML 'id' nor 'name' specified - " +
"using generated bean name [" + beanName + "]");
}
}
catch (Exception ex) {
error(ex.getMessage(), ele);
return null;
}
}
String[] aliasesArray = StringUtils.toStringArray(aliases);
return new BeanDefinitionHolder(beanDefinition, beanName, aliasesArray);
}
return null;
}
关键的方法。parseBeanDefinitionElement。下一篇会继续。