dubbo-源码阅读之bean装配过程(四)

Spring自定义schema

我们再使用dubbo进行时 会经常看到这样的标签

 <!--开启注解扫描-->
    <context:component-scan base-package="com.liqiang.service.impl"></context:component-scan>
    <!-- 提供方应用信息，用于计算依赖关系 -->
    <dubbo:application name="userSystemProvider"  />

    <!-- 服务注册中心地址 其他参数请看用户指南-->
    <dubbo:registry address="zookeeper://192.168.65.128:2181?backup=192.168.65.128:2182,192.168.65.128:2183" />
    <!-- 用dubbo协议在20880端口暴露服务 -->
    <dubbo:protocol name="dubbo" port="20880" />
    <!--发布服务-->
    <dubbo:service interface="com.liqiang.service.UserService" ref="userServiceImpl"></dubbo:service>
    <!--发布服务-->
    <dubbo:service interface="com.liqiang.service.ProductService" ref="productServiceImpl"></dubbo:service>

其实是利用spring2.0的对自定义schema的支持实现的 。下面我们模拟一一下dubbo的标签实现

1.添加POM依赖

    <properties>
        <springframework.version>4.0.0.RELEASE</springframework.version>
    </properties>
    <dependencies>
        <!-- **************************** Spring 依赖 **************************** -->
        <!-- 添加Spring-core包 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${springframework.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-expression</artifactId>
            <version>${springframework.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>${springframework.version}</version>
        </dependency>
        <!-- 添加spring-tx包 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>${springframework.version}</version>
        </dependency>
        <!-- Spring ORM 相关-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${springframework.version}</version>
        </dependency>
        <!-- 添加spring-jdbc包 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>${springframework.version}</version>
        </dependency>
        <!--添加spring-web包 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>${springframework.version}</version>
        </dependency>
        <!-- 添加spring-context包 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${springframework.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>${springframework.version}</version>
        </dependency>

        <!--添加aspectjweaver包 -->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.8.5</version>
        </dependency>
    </dependencies>

2.创建xsd文件

在resource下创建文件xsd文件dubbo.xsd

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns="http://liqiang/schema/dubbo"
            xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:beans="http://www.springframework.org/schema/beans"
            targetNamespace="http://liqiang/schema/dubbo" elementFormDefault="qualified"
            attributeFormDefault="unqualified">
    <xsd:import namespace="http://www.springframework.org/schema/beans" />
    <xsd:element name="server"><!--定义标签后缀名字-->
        <xsd:complexType>
            <xsd:complexContent>
                <xsd:extension base="beans:identifiedType">
                    <xsd:attribute name="interface" type="xsd:string" use="required"/><！--标签属性定义-->
                    <xsd:attribute name="ref" type="xsd:string" use="required" />
                </xsd:extension>
            </xsd:complexContent>
        </xsd:complexType>
    </xsd:element>

</xsd:schema>

targetNamespace:为命名空间地址

3.创建自定义spring bean标签解析器

//定义自定义的scheme解析器
public class SimpleDateFormatBeanDefinitionParser extends AbstractSingleBeanDefinitionParser {
    protected Class getBeanClass(Element element) {
        return DubboConfig.class;
    }
    protected void doParse(Element element, BeanDefinitionBuilder bean) {
        String interfaceFullName = element.getAttribute("interface");
        String refName = element.getAttribute("ref");
        if (StringUtils.hasText(interfaceFullName)) {
            bean.addPropertyValue("interfaceFullName", interfaceFullName);
        }
        if (StringUtils.hasText(refName)) {
            bean.addPropertyValue("refName", refName);
        }
    }
}

4.注册自定义解析器Handle

/**
 * 注册自定义scheme解析器
 */
public class MyNamespaceHandler extends NamespaceHandlerSupport {
    public void init() {
        //必须是elementName
        registerBeanDefinitionParser("server", new SimpleDateFormatBeanDefinitionParser());
    }
}

5.注册之定义Handle与spring产生关联

1.在resource目录下创建META-INF目录并创建spring.handlers和spring.schemas文件

spring.handlers内容

指向 自定义解析注册handle类的fullname

http\://liqiang/schema/dubbo=com.liqiang.test.MyNamespaceHandler

spring.schemas

http\://liqiang/schema/dubbo/dubbo.xsd=dubbo.xsd

6.创建spring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:dubbo="http://liqiang/schema/dubbo"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://liqiang/schema/dubbo http://liqiang/schema/dubbo/dubbo.xsd">
    <dubbo:server id="test" interface="com.liqiang.userService" ref="userServiceImpl"></dubbo:server>

</beans>

留意加粗备份为你自定义标签的命名空间和xsd

7.测试

public static void main(String[] args) {
        ApplicationContext ctx = new ClassPathXmlApplicationContext("spring-application.xml");
        DubboConfig dubboConfig = (DubboConfig) ctx.getBean("test");
        System.out.println(dubboConfig.getInterfaceFullName()+"|"+dubboConfig.getRefName());

    }

输出

Dubbo对自定义Schame实现

我们知道 自定义Schame 需要定义解析器，和注册解析的handle  所以我们直接看dubbo对应的类就行了

DubboNamespaceHandler

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

dubbo所有标签都是交给DubboBeanDefinitionParser解析的。内部根据传入的class判断是什么标签。并用对应的Config内进行封装

DubboBeanDefinitionParser

public class DubboBeanDefinitionParser implements BeanDefinitionParser {public DubboBeanDefinitionParser(Class<?> beanClass, boolean required) {
        this.beanClass = beanClass;
        this.required = required;
    }

    public BeanDefinition parse(Element element, ParserContext parserContext) {
        return parse(element, parserContext, this.beanClass, this.required);
    }

    private static BeanDefinition parse(Element element, ParserContext parserContext, Class<?> beanClass, boolean required) {
        RootBeanDefinition beanDefinition = new RootBeanDefinition();
        .........//省略部分代码
        if (ProtocolConfig.class.equals(beanClass)) {
            String[] arr$ = parserContext.getRegistry().getBeanDefinitionNames();
            len$ = arr$.length;

            for(int i$ = 0; i$ < len$; ++i$) {
                String name = arr$[i$];
                BeanDefinition definition = parserContext.getRegistry().getBeanDefinition(name);
                PropertyValue property = definition.getPropertyValues().getPropertyValue("protocol");
                if (property != null) {
                    Object value = property.getValue();
                    if (value instanceof ProtocolConfig && id.equals(((ProtocolConfig)value).getName())) {
                        definition.getPropertyValues().addPropertyValue("protocol", new RuntimeBeanReference(id));
                    }
                }
            }
        } else if (ServiceBean.class.equals(beanClass)) {
            className = element.getAttribute("class");
            if (className != null && className.length() > 0) {
                RootBeanDefinition classDefinition = new RootBeanDefinition();
                classDefinition.setBeanClass(ReflectUtils.forName(className));
                classDefinition.setLazyInit(false);
                parseProperties(element.getChildNodes(), classDefinition);
                beanDefinition.getPropertyValues().addPropertyValue("ref", new BeanDefinitionHolder(classDefinition, id + "Impl"));
            }
        } else if (ProviderConfig.class.equals(beanClass)) {
            parseNested(element, parserContext, ServiceBean.class, true, "service", "provider", id, beanDefinition);
        } else if (ConsumerConfig.class.equals(beanClass)) {
            parseNested(element, parserContext, ReferenceBean.class, false, "reference", "consumer", id, beanDefinition);
        }       .......//省略部分代码}

注意 上面并没有立刻创建对应的对象到spring容器  而是通过BeanDefinition  进行封装 class 哪些参数等。。将beanDefinition交于spring框架初始化