4.3 spring-嵌入式beans标签的解析

　　对于嵌入式的beans标签,想信大家很少使用过,或者接触过,起码,我本人就没用过. 它非常类似于Import标签所提供的功能;

使用如下:

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">

    <beans></beans>

</beans> 

　　对这个beans没什么太多可讲,解析代码如下:

 protected void doRegisterBeanDefinitions(Element root) {

         String profileSpec = root.getAttribute(PROFILE_ATTRIBUTE);

         // 处理profile属性

         /*

          * this is header...

          *

          * <beans profile = 'dev"></beans>

          *

          * <beans profile = 'production"></beans>

          *

          * web.xml

          *

          * <context-param>

          *

          * <param-name>Spring.profiles.active</param-name>

          *

          * <param-value>dev</param-value>

          *

          * </context-param>

          */

         if (StringUtils.hasText(profileSpec)) {

             Assert.state(this.environment != null,

                     "Environment must be set for evaluating profiles");

             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.

         // 专门处理解析

         BeanDefinitionParserDelegate parent = this.delegate;

         this.delegate = createDelegate(this.readerContext, root, parent);

         // 解析前留给子类实现

         preProcessXml(root);

         parseBeanDefinitions(root, this.delegate);

         // 解析后留给子类实现

         postProcessXml(root);

         this.delegate = parent;

     }