做dubbo的配置时很容易发现，dubbo有一套自己的标签，提供给开发者配置，其实每一个标签对应着一个 实体，在容器启动的时候，dubbo会对所有的配置进行解析然后将解析后的内容设置到实体里，最终dubbo会根据实体中的值生成贯穿全局的统一URL。利用自定义标签使配置简单明了化，与spring完美融合。
下面自己写一个自定义标签，主要需要如下 几个步骤：
1、编写实体类
2、编写Parser解析类
3、编写NameSpaceHandle类
4、配置spring.handlers
5、配置spring.schemas
6、配置customTag .xsd
标签实体类如下：
public class CustomTag { private String id; private String name; private Integer age; private String profession; private String address; private String phone; public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public String getProfession() { return profession; } public void setProfession(String profession) { this.profession = profession; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } public String getPhone() { return phone; } public void setPhone(String phone) { this.phone = phone; } public String toString(){ StringBuffer sb = new StringBuffer(); sb.append(id + "\n"); sb.append(name + "\n"); sb.append(age + "\n"); sb.append(profession + "\n"); sb.append(address + "\n"); sb.append(phone + "\n"); return sb.toString(); } }
标签的解析类如下:
public class CustomTagBeanDefinitionParser extends AbstractSingleBeanDefinitionParser { private final Class<?> beanClass; private final boolean required; public CustomTagBeanDefinitionParser (Class<?> beanClass, boolean required) { this.beanClass = beanClass; this.required = required; } protected Class getBeanClass(Element element) { return CustomTag.class; } protected void doParse(Element element, BeanDefinitionBuilder builder) { //通过配置文件获取相应的值，设置到bean的属性中 String id = element.getAttribute("id"); String name = element.getAttribute("name"); String age = element.getAttribute("age"); String profession = element.getAttribute("profession"); String address = element.getAttribute("address"); String phone = element.getAttribute("phone"); if (StringUtils.hasText(id)) { builder.addPropertyValue("id", id); } if (StringUtils.hasText(name)) { builder.addPropertyValue("name", name); } if (StringUtils.hasText(age)) { builder.addPropertyValue("age", age); } if (StringUtils.hasText(profession)) { builder.addPropertyValue("profession", profession); } if (StringUtils.hasText(address)) { builder.addPropertyValue("address", address); } if (StringUtils.hasText(phone)) { builder.addPropertyValue("phone", phone); } } }
NameSpaceHandle类如下：
public class CustomTagNamespaceHandler extends NamespaceHandlerSupport { @Override public void init() { //实现init方法,解析CustomTag标签 registerBeanDefinitionParser("customTag",new CustomTagBeanDefinitionParser(CustomTag.class,true)); } } spring.handlers配置，前面那一串其实可以随便配置，只要一会和后面的配置一致即可 http\://www.51gitee.net/schema/customTag=springNameSpace.CustomTagNamespaceHandler spring.schemas配置 http\://www.51gitee.net/schema/customTag/customTag.xsd=META-INF/customTag.xsd customTag.xsd的配置 <?xml version="1.0" encoding="UTF-8"?> <xsd:schema xmlns="http://www.51gitee.net/schema/customTag" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:beans="http://www.springframework.org/schema/beans" targetNamespace="http://www.51gitee.net/schema/customTag" elementFormDefault="qualified" attributeFormDefault="unqualified"> <xsd:import namespace="http://www.springframework.org/schema/beans" /> <!-- 定义element名, customTagType对应了bean的属性 --> <xsd:element name="customTag" type="customTagType"> <xsd:annotation> <xsd:documentation><![CDATA[ The customTag config ]]></xsd:documentation> </xsd:annotation> </xsd:element> <!-- 配置各属性值，有点像Mybatis配置对应的model --> <xsd:complexType name="customTagType"> <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 customTag name. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="age" type="xsd:int"> <xsd:annotation> <xsd:documentation><![CDATA[ The customTag age. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="profession" type="xsd:string"> <xsd:annotation> <xsd:documentation><![CDATA[ The customTag profession. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="address" type="xsd:string"> <xsd:annotation> <xsd:documentation><![CDATA[ The customTag address. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="phone" type="xsd:string"> <xsd:annotation> <xsd:documentation><![CDATA[ The customTag phone. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> </xsd:complexType> </xsd:schema>
最后测试
在新建一个spring的配置文件如下
<?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:common="http://www.51gitee.net/schema/customTag" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd http://www.oschina.net/schema/customTag http://www.oschina.net/schema/customTag/customTag.xsd"> <common:customTag id="test" name="chewenliang" address="bei jing" age="12" phone="18618152379" profession="技术" /> </beans>
在java代码中测试
public class TestNameSpace { public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("spring-test.xml"); CustomTag customTag= (CustomTag) context.getBean("test"); System.out.println(customTag.toString()); } }
输出结果：
test chewenliang 12 技术 bei jing 18618152379
spring的自定义标签自己很容易实现，具体要看在实际项目中如何正确的实用它，接下来会记录dubbo是如何解析、暴露服务。
