Spring自定义schema

我们再使用dubbo进行时 会经常看到这样的标签

<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

<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>

在resource下创建文件xsd文件dubbo.xsd

<！--标签属性定义-->

targetNamespace:为命名空间地址

//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);
}
}
}

/**
* 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());
}
}

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

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**">

留意加粗备份为你自定义标签的命名空间和xsd

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

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

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