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 + " ");
sb.append(name + " ");
sb.append(age + " ");
sb.append(profession + " ");
sb.append(address + " ");
sb.append(phone + " ");
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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