设计模式--模板模式

 1 protected void doRegisterBeanDefinitions(Element root) {
 2         String profileSpec = root.getAttribute(PROFILE_ATTRIBUTE);
 3         if (StringUtils.hasText(profileSpec)) {
 4             Assert.state(this.environment != null, "Environment must be set for evaluating profiles");
 5             String[] specifiedProfiles = StringUtils.tokenizeToStringArray(
 6                     profileSpec, BeanDefinitionParserDelegate.MULTI_VALUE_ATTRIBUTE_DELIMITERS);
 7             if (!this.environment.acceptsProfiles(specifiedProfiles)) {
 8                 return;
 9             }
10         }
11 
12         // Any nested <beans> elements will cause recursion in this method. In
13         // order to propagate and preserve <beans> default-* attributes correctly,
14         // keep track of the current (parent) delegate, which may be null. Create
15         // the new (child) delegate with a reference to the parent for fallback purposes,
16         // then ultimately reset this.delegate back to its original (parent) reference.
17         // this behavior emulates a stack of delegates without actually necessitating one.
18         BeanDefinitionParserDelegate parent = this.delegate;
19         this.delegate = createDelegate(this.readerContext, root, parent);
20 
21         preProcessXml(root);
22         parseBeanDefinitions(root, this.delegate);
23         postProcessXml(root);
24 
25         this.delegate = parent;
26     }

 1     /**
 2      * Allow the XML to be extensible by processing any custom element types first,
 3      * before we start to process the bean definitions. This method is a natural
 4      * extension point for any other custom pre-processing of the XML.
 5      * <p>The default implementation is empty. Subclasses can override this method to
 6      * convert custom elements into standard Spring bean definitions, for example.
 7      * Implementors have access to the parser‘s bean definition reader and the
 8      * underlying XML resource, through the corresponding accessors.
 9      * @see #getReaderContext()
10      */
11     protected void preProcessXml(Element root) {
12     }