dubbo源码学习(二) : spring 自定义标签

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。

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