自定义Spring命名空间

1、定义schema约束xsd文件

      将xsd文件放到 META-INF 目录下

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
            xmlns:beans="http://www.springframework.org/schema/beans"
            xmlns:tool="http://www.springframework.org/schema/tool"
            xmlns="http://www.seasy.com/schema/seasy"
            targetNamespace="http://www.seasy.com/schema/seasy">
            
    <xsd:import namespace="http://www.w3.org/XML/1998/namespace"/>
    <xsd:import namespace="http://www.springframework.org/schema/beans"/>
    <xsd:import namespace="http://www.springframework.org/schema/tool"/>
    
	<xsd:annotation>
        <xsd:documentation>
            <![CDATA[ Namespace support for the seasy framework ]]>
        </xsd:documentation>
    </xsd:annotation>
    
    <!-- type -->
    <xsd:complexType name="serviceType">
        <xsd:attribute name="id" type="xsd:ID">
            <xsd:annotation>
                <xsd:documentation><![CDATA[ The unique identifier for a bean. ]]></xsd:documentation>
            </xsd:annotation>
        </xsd:attribute>
        <xsd:attribute name="name" type="xsd:string" use="required">
            <xsd:annotation>
                <xsd:documentation><![CDATA[ The service name. ]]></xsd:documentation>
            </xsd:annotation>
        </xsd:attribute>
        <xsd:attribute name="description" type="xsd:string" use="optional" default="">
            <xsd:annotation>
                <xsd:documentation><![CDATA[ The service description. ]]></xsd:documentation>
            </xsd:annotation>
        </xsd:attribute>
    </xsd:complexType>
    
    <!-- element -->
    <xsd:element name="service" type="serviceType">
        <xsd:annotation>
            <xsd:documentation><![CDATA[ The service config ]]></xsd:documentation>
        </xsd:annotation>
    </xsd:element>
    
</xsd:schema>

 

 

2、创建自定义标签对应的Config类：

public class ServiceConfig {
	private String name;
	private String description;
	
	public String getName() {
		return name;
	}
	
	public void setName(String name) {
		this.name = name;
	}
	
	public String getDescription() {
		return description;
	}
	
	public void setDescription(String description) {
		this.description = description;
	}
}

 

 

3、创建自定义标签的解析器类：

public class ServiceBeanDefinitionParser extends AbstractSingleBeanDefinitionParser{
	@Override
	protected void doParse(Element element, ParserContext parserContext, BeanDefinitionBuilder builder) {
		String name = element.getAttribute("name");
		String description = element.getAttribute("description");
		
		builder.addPropertyValue("name", name);
		builder.addPropertyValue("description", description);
	}
	
	@Override
	protected Class<?> getBeanClass(Element element) {
		return ServiceConfig.class;
	}
}

 

 

4、创建自定义NamespaceHandler类：

public class SeasyNamespaceHandler extends NamespaceHandlerSupport{
	@Override
	public void init() {
		//注册bean配置信息的解析器
		//service 对应到beans xml文件的节点元素名
		//<seasy:service> </seasy:service>
		registerBeanDefinitionParser("service", new ServiceBeanDefinitionParser());
	}
}

 

 

5、在 META-INF 目录下新建文件 spring.schemas

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

 

 

6、在 META-INF 目录下新建文件 spring.handlers

http\://www.seasy.com/schema/seasy=com.seasy.namespace.SeasyNamespaceHandler

 

7、创建beans的xml配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:seasy="http://www.seasy.com/schema/seasy"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.seasy.com/schema/seasy http://www.seasy.com/schema/seasy.xsd">

	<seasy:service id="userService" name="UserService" description="" />
</beans>

 

8、测试类

public class NamespaceHandlerTest {
	public static void main(String[] args) {
		ClassPathXmlApplicationContext applicationContext
			= new ClassPathXmlApplicationContext(new String[]{"seasy-beans.xml"}, false);
		applicationContext.setValidating(true);
		applicationContext.refresh();
		
		ServiceConfig serviceConfig = applicationContext.getBean(ServiceConfig.class);
		System.out.println(serviceConfig.getName());
	}
}

 

 自定义标签有点复杂，通过以下方案可以实现同样的功能：

       1、创建自定义注解类，对应到自定义标签的Config类

       2、创建BeanFactoryPostProcessor的子类，在Bean工厂初始化之前根据自定义注解类扫描类

       3、创建ClassPathBeanDefinitionScanner的子类，用于根据自定义注解类扫描类，并注册到容器中