Spring下自定义xml标签

今天尝试在spring框架下自定义一个标签，为以后定义一组标签，来控制流程处理做准备。

自定义一个标签需要以下步骤：

1. 确定标签的属性，编写对应的java bean
2. 根据java bean编写对应xsd文件
3. 编写标签注册类NamespaceHandler和标签解析类BeanDefinitionParser
4. 配置spring.handlers和spring.schmas
5. 在spring的配置文件中使用标签

第一步：编写对应的java bean
我计划定一个标签facade，其属性包括id，interCode，reqEvent，resEvent
所以我的java bean如下：

public class Facade {    private String id;    private String interCode;    private String reqEvent;    private String resEvent;    public String getId() {        return id;    }    public void setId(String id) {        this.id = id;    }    public String getInterCode() {        return interCode;    }    public void setInterCode(String interCode) {        this.interCode = interCode;    }    public String getReqEvent() {        return reqEvent;    }    public void setReqEvent(String reqEvent) {        this.reqEvent = reqEvent;    }    public String getResEvent() {        return resEvent;    }    public void setResEvent(String resEvent) {        this.resEvent = resEvent;    }}

第二步：根据java bean编写对应xsd文件
对应的xsd文件如下：

<?xml version="1.0" encoding="UTF-8"?><xsd:schema xmlns="http://www.luxy.org/li" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:beans="http://www.springframework.org/schema/beans" targetNamespace="http://www.luxy.org/li" elementFormDefault="qualified" attributeFormDefault="unqualified">    <xsd:import namespace="http://www.springframework.org/schema/beans" />    <xsd:element name="facade" type="facadeType"></xsd:element>    <xsd:complexType name="facadeType">        <xsd:attribute name="id" type="xsd:ID" use="required" />        <xsd:attribute name="interCode" type="xsd:string"></xsd:attribute>        <xsd:attribute name="reqEvent" type="xsd:string"></xsd:attribute>        <xsd:attribute name="resEvent" type="xsd:string"></xsd:attribute>    </xsd:complexType></xsd:schema>

第三步：编写标签注册类NamespaceHandler和标签解析类BeanDefinitionParser

NamespaceHandler：

import org.springframework.beans.factory.xml.NamespaceHandlerSupport;import com.slys.core.schema.parser.FacadeParser;public class LiNamespaceHandler extends NamespaceHandlerSupport {  public void init()  {      registerBeanDefinitionParser("facade", new FacadeParser());  }}

BeanDefinitionParser:

public class FacadeParser extends AbstractSimpleBeanDefinitionParser {    @Override    protected Class<Facade> getBeanClass(Element element) {        return Facade.class;    }    protected void doParse(Element element, ParserContext parserContext, BeanDefinitionBuilder builder) {        try        {            builder.addPropertyValue("id", element.getAttribute("id"));            builder.addPropertyValue("interCode", element.getAttribute("interCode"));            builder.addPropertyValue("reqEvent",  element.getAttribute("reqEvent"));            builder.addPropertyValue("resEvent", element.getAttribute("resEvent"));        } catch (Exception e) {          parserContext.getReaderContext().error("class " + FacadeParser.class.getName() + " can not be create", element, null, e);        }       }}

第四步：配置spring.handlers和spring.schmas

spring.handlers：

http\://www.luxy.org/li=com.slys.core.schema.LiNamespaceHandler

spring.schemas:

http\://www.luxy.org/li.xsd=com/slys/core/schema/li.xsd

第五步：在spring的配置文件中使用标签

<?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:li="http://www.luxy.org/li" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.luxy.org/li http://www.luxy.org/li.xsd">    <li:facade id="abcd" interCode="1234" reqEvent="test" resEvent="res"></li:facade></beans>

大功告成！！！

测试：

    public static void main(String[] args) {        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("classpath:spring-config.xml");        Facade facade = (Facade) context.getBean("abcd");        System.out.println(facade.getId());        System.out.println(facade.getInterCode());        System.out.println(facade.getReqEvent());        System.out.println(facade.getResEvent());    }

输出结果：

abcd1234testres

在尝试过程中遇到的问题：
1、xsd中没有加id属性，报错：cvc-complex-type.3.2.2: 元素 ‘li:facade’ 中不允许出现属性 ‘id’，加上后错误消失
2、id的值使用“1234”，报错：cvc-datatype-valid.1.2.1: ‘1234’ 不是 ‘NCName’ 的有效值，理解为不能使用纯数字为id赋值
3、spring.handlers和spring.schmas的存放位置，放在src/main/resources目录下，新建META-INF文件夹
4、使用maven打jar包时，发现不能将li.xsd文件打进去jar中，解决办法：

在pom.xml增加

<build>     <resources>         <resource>             <directory>src/main/resources</directory>             <includes>                 <include>**/*.*</include>             </includes>         </resource>         <resource>             <directory>src/main/java</directory>             <includes>                 <include>**/*.xml</include>                 <include>**/*.xsd</include>             </includes>         </resource>     </resources> </build>