自定义spring标签解析器

bean在spring中，首先是先将配置文件中的bean信息解析成BeanDefinition即bean定义信息对象。

对于bean的申明有多中方式，拿典型的xml申明来说，其大致的流程:

加载xml文件 ：AbstractBeanDefinitionReader#loadBeanDefinitions(String, Set< Resource> actualResources)

根据xml schema文件解析校验xml配置成document：XmlBeanDefinitionReader#doLoadDocument

根据xml的namespace获取到对应的解析器NamespaceHandler：BeanDefinitionParserDelegate#parseCustomElement(Element, BeanDefinition)

将xml中的属性赋给BeanDefinition：实现类AbstractSingleBeanDefinitionParser

public class MyTag {

	private String tagName;

	public void setTagName(String tagName) {
		this.tagName = tagName;
	}

	public String getTagName() {
		return tagName;
	}
}

import org.springframework.beans.factory.xml.NamespaceHandlerSupport;

public class TagNamespaceHandler extends NamespaceHandlerSupport {



	@Override
	public void init() {
		registerBeanDefinitionParser("self", new TagSingleBeanDefinitionParser());
	}
}

import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.xml.AbstractSingleBeanDefinitionParser;
import org.w3c.dom.Element;

public class TagSingleBeanDefinitionParser extends AbstractSingleBeanDefinitionParser {


	@Override
	protected Class<?> getBeanClass(Element element) {
		return MyTag.class;
	}

	@Override
	protected void doParse(Element element, BeanDefinitionBuilder builder) {

		String tagName = element.getAttribute("tagName");

		builder.addPropertyValue("tagName", tagName);

	}
}

spring.handlers

http\://www.xiahaila.com/schema/tag=com.xiahaila.study.spring.tag.TagNamespaceHandler

spring.schemas

http\://www.xiahaila.com/schema/tag.xsd=META-INF/tag.xsd

tag.xsd

<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema"
        targetNamespace="http://www.xiahaila.com/schema/tag"
        xmlns:tns="http://www.xiahaila.com/schema/tag"
        elementFormDefault="qualified">
    <element name="self">
        <complexType>
            <attribute name ="id" type = "string"/>
            <attribute name="tagName" type="string"/>
        </complexType>
    </element>
</schema>

xml文件bean信息配置

	<beans xmlns="http://www.springframework.org/schema/beans"
	   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	   xmlns:context="http://www.springframework.org/schema/context"
	   xmlns:aop="http://www.springframework.org/schema/aop"
	   xmlns:task="http://www.springframework.org/schema/task"
	   xmlns:tag="http://www.xiahaila.com/schema/tag"
	   xsi:schemaLocation="http://www.springframework.org/schema/beans
		http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/context
		http://www.springframework.org/schema/context/spring-context.xsd
		http://www.springframework.org/schema/task
		http://www.springframework.org/schema/task/spring-task.xsd
		http://www.springframework.org/schema/aop
		http://www.springframework.org/schema/aop/spring-aop.xsd
		http://www.xiahaila.com/schema/tag
		http://www.xiahaila.com/schema/tag.xsd">


	<tag:self id="selfTag" tagName="xxxxxnnnnnns" ></tag:self>
</beans>

spring.schemas 放xml和schema的映射

spring.handlers 放xml属性和class属性的赋值和创建beanDefine