dubbo-探索之旅(六)---结合spring

这节来看看spring的schema是怎么在dubbo中进行使用的。

1）看看dubbo中的dubbo-registry-simple.xml文件，这个文件是dubbo在spring中的bean基于dubbo自己定义的schema文件来配置的。
有了上节介绍的知识，现在来看看这个文件就很好理解了。

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:dubbo="http://code.alibabatech.com/schema/dubbo" //dubbo定义
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
    http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd">//dubbo定义的XSD文件

	<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="systemPropertiesModeName" value="SYSTEM_PROPERTIES_MODE_OVERRIDE" />
        <property name="location" value="classpath:dubbo.properties" />
    </bean>
	
    <dubbo:application name="${dubbo.application.name}" owner="${dubbo.application.owner}" />
    
    <dubbo:protocol name="dubbo" port="${dubbo.protocol.port}" heartbeat="180000" />
    
    <dubbo:service id="registryServiceConfig" interface="com.alibaba.dubbo.registry.RegistryService" ref="registryService" registry="N/A" ondisconnect="disconnect" callbacks="1000">
        <dubbo:method name="subscribe"><dubbo:argument index="1" callback="true" /></dubbo:method>
        <dubbo:method name="unsubscribe"><dubbo:argument index="1" callback="false" /></dubbo:method>
    </dubbo:service>
    
    <bean id="registryService" class="com.alibaba.dubbo.registry.simple.SimpleRegistryService" />

</beans>

有以上的配置文件，就应该有相对应的一套schema体现。

2）接下来我们看看NamespaceHandlerSupport：
在dubbo中DubboNamespaceHandler继承了NamespaceHandlerSupport：
根据XSD文件中的节点名称找到自己制定的BeanDefinitionParser，然后由BeanDefinitionParser完成具体的解析工作。

public class DubboNamespaceHandler extends NamespaceHandlerSupport {

	static {
		Version.checkDuplicate(DubboNamespaceHandler.class);
	}

	public void init() {
	    registerBeanDefinitionParser("application", new DubboBeanDefinitionParser(ApplicationConfig.class, true));
        registerBeanDefinitionParser("module", new DubboBeanDefinitionParser(ModuleConfig.class, true));
        registerBeanDefinitionParser("registry", new DubboBeanDefinitionParser(RegistryConfig.class, true));
        registerBeanDefinitionParser("monitor", new DubboBeanDefinitionParser(MonitorConfig.class, true));
        registerBeanDefinitionParser("provider", new DubboBeanDefinitionParser(ProviderConfig.class, true));
        registerBeanDefinitionParser("consumer", new DubboBeanDefinitionParser(ConsumerConfig.class, true));
        registerBeanDefinitionParser("protocol", new DubboBeanDefinitionParser(ProtocolConfig.class, true));
        registerBeanDefinitionParser("service", new DubboBeanDefinitionParser(ServiceBean.class, true));
        registerBeanDefinitionParser("reference", new DubboBeanDefinitionParser(ReferenceBean.class, false));
        registerBeanDefinitionParser("annotation", new DubboBeanDefinitionParser(AnnotationBean.class, true));
    }

}

例如：registerBeanDefinitionParser("application", new DubboBeanDefinitionParser(ApplicationConfig.class, true));
会根据application名称，找到XSD中配置的BEAN信息，由DubboBeanDefinitionParser来完成解析工作。
XSD中application节点：

<xsd:element name="application" type="applicationType">
		<xsd:annotation> 
			<xsd:documentation><![CDATA[ The application config ]]></xsd:documentation> 
		</xsd:annotation>
	</xsd:element>


<xsd:complexType name="applicationType">
		<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 application name. ]]></xsd:documentation>
			</xsd:annotation>
		</xsd:attribute>
		<xsd:attribute name="version" type="xsd:string">
			<xsd:annotation>
				<xsd:documentation><![CDATA[ The application version. ]]></xsd:documentation>
			</xsd:annotation>
		</xsd:attribute>
		<xsd:attribute name="owner" type="xsd:string">
			<xsd:annotation>
				<xsd:documentation><![CDATA[ The application owner name (email prefix). ]]></xsd:documentation>
			</xsd:annotation>
		</xsd:attribute>
		<xsd:attribute name="organization" type="xsd:string">
			<xsd:annotation>
				<xsd:documentation><![CDATA[ The organization name. ]]></xsd:documentation>
			</xsd:annotation>
		</xsd:attribute>
		<xsd:attribute name="architecture" type="xsd:string">
			<xsd:annotation>
				<xsd:documentation><![CDATA[ The architecture. ]]></xsd:documentation>
			</xsd:annotation>
		</xsd:attribute>
		<xsd:attribute name="environment" type="xsd:string">
			<xsd:annotation>
				<xsd:documentation><![CDATA[ The application environment, eg: dev/test/run ]]></xsd:documentation>
			</xsd:annotation>
		</xsd:attribute>
		<xsd:attribute name="compiler" type="xsd:string">
			<xsd:annotation>
				<xsd:documentation><![CDATA[ The java code compiler. ]]></xsd:documentation>
			</xsd:annotation>
		</xsd:attribute>
		<xsd:attribute name="logger" type="xsd:string">
			<xsd:annotation>
				<xsd:documentation><![CDATA[ The application logger. ]]></xsd:documentation>
			</xsd:annotation>
		</xsd:attribute>
		<xsd:attribute name="registry" type="xsd:string" use="optional">
			<xsd:annotation>
				<xsd:documentation><![CDATA[ The application registry. ]]></xsd:documentation>
			</xsd:annotation>
		</xsd:attribute>
		<xsd:attribute name="monitor" type="xsd:string" use="optional">
			<xsd:annotation>
				<xsd:documentation><![CDATA[ The application monitor. ]]></xsd:documentation>
			</xsd:annotation>
		</xsd:attribute>
		<xsd:attribute name="default" type="xsd:string" use="optional">
			<xsd:annotation>
				<xsd:documentation><![CDATA[ Is default. ]]></xsd:documentation>
			</xsd:annotation>
		</xsd:attribute>
	</xsd:complexType>

对应的bean信息：
ApplicationConfig类：

// 应用名称
    private String               name;

    // 模块版本
    private String               version;

    // 应用负责人
    private String               owner;

    // 组织名(BU或部门)
    private String               organization;

    // 分层
    private String               architecture;

    // 环境，如：dev/test/run
    private String               environment;

    // Java代码编译器
    private String               compiler;

    // 日志输出方式
    private String               logger;

    // 注册中心
    private List<RegistryConfig> registries;

    // 服务监控
    private MonitorConfig        monitor;

    // 是否为缺省
    private Boolean              isDefault;

DubboBeanDefinitionParser自然就会实现BeanDefinitionParser接口了。
把XSD文件中配置的值写到bean(ApplicationConfig)中

dubbo对于每一个节点的解析都是同一个解析器，这点的做法有点待商榷。

3）下面就是应该是spring.handlers和spring.schemas了
指定http://code.alibabatech.com/schema/dubbo/dubbo.xsd对于的xsd文件
在META-INF/spring.schemas定义
http\://code.alibabatech.com/schema/dubbo/dubbo.xsd=META-INF/dubbo.xsd
在META-INF/spring.handlers定义
http\://code.alibabatech.com/schema/dubbo=com.alibaba.dubbo.config.spring.schema.DubboNamespaceHandler

经过这2节的介绍，可以比较清楚的了解了，dubbo和spring的结合了！