继续上一次的分析
XmlBeanDefinitionReader.java 中
1、registerBeanDefinitions方法
documentReader.registerBeanDefinitions(doc, createReaderContext(resource));
注册Bean definition， 第二个参数是createReaderContext(resource)
2、createReaderContext方法
3、XmlReaderContext
XmlReaderContext继承自ReaderContext，和XmlBeanDefinitionReader一起使用，提供了访问NamespaceHandlerResolver
4、registerBeanDefinitions方法
方法作用：见方法的英文描述
5、doRegisterBeanDefinitions方法，参数为xml文档的根元素
/**
* Register each bean definition within the given root {@code <beans/>} element.
* @throws IllegalStateException if {@code <beans profile="..."} attribute is present
* and Environment property has not been set
* @see #setEnvironment
*/
protected void doRegisterBeanDefinitions(Element root) {
String profileSpec = root.getAttribute(PROFILE_ATTRIBUTE);
if (StringUtils.hasText(profileSpec)) {
Assert.state(this.environment != null, "environment property must not be null");
String[] specifiedProfiles = StringUtils.tokenizeToStringArray(profileSpec, BeanDefinitionParserDelegate.MULTI_VALUE_ATTRIBUTE_DELIMITERS);
if (!this.environment.acceptsProfiles(specifiedProfiles)) {
return;
}
}
// any nested <beans> elements will cause recursion in this method. In
// order to propagate and preserve <beans> default-* attributes correctly,
// keep track of the current (parent) delegate, which may be null. Create
// the new (child) delegate with a reference to the parent for fallback purposes,
// then ultimately reset this.delegate back to its original (parent) reference.
// this behavior emulates a stack of delegates without actually necessitating one.
BeanDefinitionParserDelegate parent = this.delegate;
this.delegate = createHelper(readerContext, root, parent);
preProcessXml(root);
parseBeanDefinitions(root, this.delegate);
postProcessXml(root);
this.delegate = parent;
}
这里用到了模板方法的设计模式
preProcessXml(root); parseBeanDefinitions(root, this.delegate); postProcessXml(root);
这三个方法执行顺序是不变的。子类可以重写preProcessXml方法和postProcessXml方法， 实现对XML配置文件的自定义扩展。类似于JUnit中的setUp，testXXX与tearDown方法
。
6、BeanDefinitionParserDelegate类： 有状态的委托类，用来解析Xml中bean的定义
定义的成员变量
public static final String BEANS_NAMESPACE_URI = "http://www.springframework.org/schema/beans"; public static final String MULTI_VALUE_ATTRIBUTE_DELIMITERS = ",; "; /** @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; /** * 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"; 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; /** * 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>();
7、createHelper方法
protected BeanDefinitionParserDelegate createHelper(XmlReaderContext readerContext, Element root, BeanDefinitionParserDelegate parentDelegate) {
BeanDefinitionParserDelegate delegate = new BeanDefinitionParserDelegate(readerContext, environment);
delegate.initDefaults(root, parentDelegate);
return delegate;
}
this.readerContext.fireDefaultsRegistered(this.defaults);
激发默认值的注册
8、initDefaults方法
/**
* 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);
}
9、populateDefaults方法 装配根元素beans的默认值
/**
* 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 parentDefaults 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));
}