dubbo源码学习（三）基础知识：spring 自定义标签

来源：互联网发布：网络诈骗主题班会记录编辑：程序博客网时间：2024/05/29 07:20

初学dubbo的源码，只做尝试性的去学习，做为自己学习的一个记录，各位看官如果觉得写的有错误或理解的不对，请在留言区告诉我，互相学习。本人能力有限，有大神进入时请指点。

我们在做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chewl.xsd

实体类如下：

public class Chewl {    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 ChewlBeanDefinitionParserS extends AbstractSingleBeanDefinitionParser {    private final Class<?> beanClass;    private final boolean required;    public ChewlBeanDefinitionParserS(Class<?> beanClass, boolean required) {        this.beanClass = beanClass;        this.required = required;    }    protected Class getBeanClass(Element element) {        return Chewl.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 ChewlNamespaceHandler extends NamespaceHandlerSupport {    @Override    public void init() {        //实现init方法,解析chewl标签        registerBeanDefinitionParser("chewl",new ChewlBeanDefinitionParserS(Chewl.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.oschina.net/schema/chewl=springNameSpace.ChewlNamespaceHandler

spring.schemas配置

http\://www.oschina.net/schema/chewl/chewl.xsd=META-INF/chewl.xsd

chewl.xsd的配置

<?xml version="1.0" encoding="UTF-8"?><xsd:schema        xmlns="http://www.oschina.net/schema/chewl"        xmlns:xsd="http://www.w3.org/2001/XMLSchema"        xmlns:beans="http://www.springframework.org/schema/beans"        targetNamespace="http://www.oschina.net/schema/chewl"        elementFormDefault="qualified"        attributeFormDefault="unqualified">    <xsd:import namespace="http://www.springframework.org/schema/beans" />    <!-- 定义element名,chewlType对应了bean的属性  -->    <xsd:element name="chewl" type="chewlType">        <xsd:annotation>            <xsd:documentation><![CDATA[ The chewl 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="chewlType">        <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 chewl name. ]]></xsd:documentation>            </xsd:annotation>        </xsd:attribute>        <xsd:attribute name="age" type="xsd:int">            <xsd:annotation>                <xsd:documentation><![CDATA[ The chewl age. ]]></xsd:documentation>            </xsd:annotation>        </xsd:attribute>        <xsd:attribute name="profession" type="xsd:string">            <xsd:annotation>                <xsd:documentation><![CDATA[ The chewl profession. ]]></xsd:documentation>            </xsd:annotation>        </xsd:attribute>        <xsd:attribute name="address" type="xsd:string">            <xsd:annotation>                <xsd:documentation><![CDATA[ The chewl address. ]]></xsd:documentation>            </xsd:annotation>        </xsd:attribute>        <xsd:attribute name="phone" type="xsd:string">            <xsd:annotation>                <xsd:documentation><![CDATA[ The chewl 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.oschina.net/schema/chewl"       xsi:schemaLocation="     http://www.springframework.org/schema/beans     http://www.springframework.org/schema/beans/spring-beans-3.2.xsd     http://www.oschina.net/schema/chewl     http://www.oschina.net/schema/chewl/chewl.xsd">    <common:chewl 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");        Chewl chewl = (Chewl) context.getBean("test");        System.out.println(chewl.toString());    }}

输出结果：

testchewenliang12技术bei jing18618152379

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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