基于xml schema的扩展标签
xml schema是spring 2.0版本之后引入的，在之后的2.5和3.x加入了新的元素。引入的主要动机在于：虽说spring把<bean/>中一切皆为对象，但在开发人员的角度上讲，我们要在Spring中具体化或抽象化一些东西，比如具体化单值、集合；或特定于具体应用的抽象比如AOP，事务。那不得不在spring中配置一些基础设施bean。或第三方框架支持我们都使用过spring Security框架，说实在的如果不使用security标签，我们必须为每个过滤器有一个<bean/>定义。所以我们为了方便不得不去自定义标签，xml schema将适用。

引入schema
dtd配置

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN 2.0//EN"    "http://www.springframework.org/dtd/spring-beans-2.0.dtd"><beans><!-- bean definitions here --></beans>

schema配置

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"><!-- bean definitions here --></beans>

以上配置复制粘贴就行，其中schemaLocation不是必须的，但在开发可以通过他在jar中找到spring-beans.xsd。接下来看下spring中提供的自定义标签.

util schema
主要处理集合，对象或类域。使用之前，配置schema头

<?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:util="http://www.springframework.org/schema/util"       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd"><!-- bean definitions here --></beans> 

<util:constant/>
使用之前

<bean id="..." />  </property></bean>

比较复杂的构造基本通过FactoryBean实现，FieldRetrievingFactoryBean检索类或对象的字段。
基于schema的配置

<bean id="..." name="code"><!-- target bean to be referenced by name --><bean id="testBean" scope="prototype">  <property name="age" value="10"/>  <property name="spouse">    <bean value="11"/>    </bean>  </property></bean><!-- will result in 10, which is the value of property 'age' of bean 'testBean' --><bean id="testBean.age" name="code"><!-- target bean to be referenced by name --><bean id="testBean" scope="prototype">  <property name="age" value="10"/>  <property name="spouse">    <bean value="11"/>    </bean>  </property></bean><!-- will result in 10, which is the value of property 'age' of bean 'testBean' --><util:property-path id="name" path="testBean.age"/>

<util:properties/>
使用之前

<!-- creates a java.util.Properties instance with values loaded from the supplied location --><bean id="jdbcConfiguration" value="classpath:com/foo/jdbc-production.properties"/></bean>

PropertiesFactoryBean实例化java.util.Properties，载入location指定Resource资源。
基于schema设置

<!-- creates a java.util.Properties instance with values loaded from the supplied location --><util:properties id="jdbcConfiguration" location="classpath:com/foo/jdbc-production.properties"/>

<util:list/>
使用之前

<!-- creates a java.util.List instance with values loaded from the supplied 'sourceList' --><bean id="emails" name="code"><!-- creates a java.util.List instance with the supplied values --><util:list id="emails" list-name="code"><!-- creates a java.util.Map instance with values loaded from the supplied 'sourceMap' --><bean id="emails" value="pechorin@hero.org"/>        <entry key="raskolnikov" value="raskolnikov@slums.org"/>        <entry key="stavrogin" value="stavrogin@gov.org"/>        <entry key="porfiry" value="porfiry@gov.org"/>      </map>  </property></bean>

MapFactoryBean创建了一个Map
基于schema配置

<!-- creates a java.util.Map instance with the supplied key-value pairs --><util:map id="emails" map-value="pechorin@hero.org"/>    <entry key="raskolnikov" value="raskolnikov@slums.org"/>    <entry key="stavrogin" value="stavrogin@gov.org"/>    <entry key="porfiry" value="porfiry@gov.org"/></util:map>

<util:set/>
使用之前

<!-- creates a java.util.Set instance with values loaded from the supplied 'sourceSet' --><bean id="emails" name="code"><util:set id="emails" set-name="code"><?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:jee="http://www.springframework.org/schema/jee"       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee.xsd"><!-- bean definitions here --></beans>

<jee:jndi-lookup/> 简单
使用之前

<bean id="dataSource" value="jdbc/MyDataSource"/></bean><bean id="userDao" ref="dataSource"/></bean

基于schema配置

<jee:jndi-lookup id="dataSource" jndi-name="jdbc/MyDataSource"/><bean id="userDao" ref="dataSource"/></bean>

<jee:jndi-lookup/> 单环境设置
使用之前

<bean id="simple" value="jdbc/MyDataSource"/>    <property name="jndiEnvironment">        <props>            <prop key="foo">bar</prop>        </props>    </property></bean>

基于schema配置

<jee:jndi-lookup id="simple" jndi-name="jdbc/MyDataSource">    <jee:environment>foo=bar</jee:environment></jee:jndi-lookup>

<jee:jndi-lookup/> 多环境设置
使用之前

<bean id="simple" value="jdbc/MyDataSource"/>    <property name="jndiEnvironment">        <props>            <prop key="foo">bar</prop>            <prop key="ping">pong</prop>        </props>    </property></bean>

基于schema配置

<jee:jndi-lookup id="simple" jndi-name="jdbc/MyDataSource">    <jee:environment>        foo=bar        ping=pong</jee:environment></jee:jndi-lookup>

<jee:jndi-lookup/> 复杂设置
使用之前

<bean id="simple" value="jdbc/MyDataSource"/>    <property name="cache" value="true"/>    <property name="resourceRef" value="true"/>    <property name="lookupOnStartup" value="false"/>    <property name="expectedType" value="com.myapp.DefaultFoo"/>    <property name="proxyInterface" value="com.myapp.Foo"/></bean>

基于schema配置

<jee:jndi-lookup id="simple"             jndi-name="jdbc/MyDataSource"             cache="true"             resource-ref="true"             lookup-on-startup="false"             expected-type="com.myapp.DefaultFoo"             proxy-interface="com.myapp.Foo"/>

<jee:local-slsb/> 简单
<jee:local-slsb/>配置一个本地EJB无状态会话BEAN
使用之前

<bean id="simple"      value="ejb/RentalServiceBean"/>  <property name="businessInterface" value="com.foo.service.RentalService"/></bean>

基于schema配置

<jee:local-slsb id="simpleSlsb" jndi-name="ejb/RentalServiceBean"    business-interface="com.foo.service.RentalService"/>

<jee:local-slsb/>复杂配置
使用之前

<bean id="complexLocalEjb"      value="ejb/RentalServiceBean"/>  <property name="businessInterface" value="com.foo.service.RentalService"/>  <property name="cacheHome" value="true"/>  <property name="lookupHomeOnStartup" value="true"/>  <property name="resourceRef" value="true"/></bean>

基于schema配置

<jee:local-slsb id="complexLocalEjb"    jndi-name="ejb/RentalServiceBean"    business-interface="com.foo.service.RentalService"    cache-home="true"    lookup-home-on-startup="true"    resource-ref="true">

<jee:remote-slsb/>
<jee:remote-slsb/>配置一个远程EJB无状态会话BEAN
使用之前

<bean id="complexRemoteEjb"      value="ejb/MyRemoteBean"/>  <property name="businessInterface" value="com.foo.service.RentalService"/>  <property name="cacheHome" value="true"/>  <property name="lookupHomeOnStartup" value="true"/>  <property name="resourceRef" value="true"/>  <property name="homeInterface" value="com.foo.service.RentalService"/>  <property name="refreshHomeOnConnectFailure" value="true"/></bean>

基于schema配置

<jee:remote-slsb id="complexRemoteEjb"    jndi-name="ejb/MyRemoteBean"    business-interface="com.foo.service.RentalService"    cache-home="true"    lookup-home-on-startup="true"    resource-ref="true"    home-interface="com.foo.service.RentalService"    refresh-home-on-connect-failure="true">

lang schema
lang标签用来暴露用脚本语言写的bean,比如Jruby,Groovy,Beanshell

<?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:lang="http://www.springframework.org/schema/lang"       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/lang http://www.springframework.org/schema/lang/spring-lang.xsd"><!-- bean definitions here --></beans>

jms schema
处理JMS相关的BEAN

<?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:jms="http://www.springframework.org/schema/jms"       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/jms http://www.springframework.org/schema/jms/spring-jms.xsd"><!-- bean definitions here --></beans>

tx (transaction) schema
事务处理

<?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:aop="http://www.springframework.org/schema/aop"       xmlns:tx="http://www.springframework.org/schema/tx"       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsdhttp://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd"><!-- bean definitions here --></beans>

aop schema

<?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:aop="http://www.springframework.org/schema/aop"       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd"><!-- bean definitions here --></beans>

context schema
spring 2.5之后才有

<?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:context="http://www.springframework.org/schema/context"       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"><!-- bean definitions here --></beans>

<property-placeholder/>
根据指定资源文件(spring resource)激活${},用 PropertyPlaceholderConfigurer实现

<annotation-config/>
激活侦测配置bean上的注解
@Required ,@Autowired,@PreDestroy , @Resource , @PersistenceContext,@PersistenceUnit

<component-scan/> 自动侦测类，注解
<load-time-weaver/> 使用AspectJ
<spring-configured/> 使用AspectJ用在领域对象
<mbean-export/>导出Mbean

jdbc schema
配置内嵌数据库和初始化内嵌数据库

<?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:jdbc="http://www.springframework.org/schema/jdbc"       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc.xsd"><!-- bean definitions here --></beans>

<jdbc:embedded-database/>内嵌数据库支持 HSQL, H2, Derby

<jdbc:embedded-database id="dataSource">        <jdbc:script location="classpath:schema.sql"/>        <jdbc:script location="classpath:test-data.sql"/>    </jdbc:embedded-database>

<jdbc:initialize-database />
初始化内嵌数据库

<jdbc:initialize-database data-source="dataSource">  <jdbc:script location="classpath:com/foo/sql/db-schema.sql"/>  <jdbc:script location="classpath:com/foo/sql/db-test-data.sql"/></jdbc:initialize-database>

自定义扩展标签

编写schema实现解析标签的NamespaceHandler实现BeanDefinitionParser 钩入以上实现配置到Spring中

实现bean定义如下

<myns:dateformat id="dateFormat"    pattern="yyyy-MM-dd HH:mm"    lenient="true"/>

编写schema

<!-- myns.xsd (inside package org/springframework/samples/xml) --><?xml version="1.0" encoding="UTF-8"?><xsd:schema xmlns="http://www.mycompany.com/schema/myns"    xmlns:xsd="http://www.w3.org/2001/XMLSchema"    xmlns:beans="http://www.springframework.org/schema/beans"    targetNamespace="http://www.mycompany.com/schema/myns"    elementFormDefault="qualified"    attributeFormDefault="unqualified">   <xsd:import namespace="http://www.springframework.org/schema/beans"/>   <xsd:element name="dateformat">      <xsd:complexType>         <xsd:complexContent>            <xsd:extension base="beans:identifiedType">               <xsd:attribute name="lenient" type="xsd:boolean"/>               <xsd:attribute name="pattern" type="xsd:string" use="required"/>            </xsd:extension>         </xsd:complexContent>      </xsd:complexType>   </xsd:element></xsd:schema>

2.编写NamespaceHandler
NamespaceHandler 接口有三个方法
init():第一次被使用时调用，注册BeanDefinitionParser
BeanDefinition parse(Element, ParserContext):作为顶级元素时被调用
BeanDefinitionHolder decorate(Node, BeanDefinitionHolder, ParserContext) :作为内嵌bean或不同namespace时被调用

package org.springframework.samples.xml;import org.springframework.beans.factory.xml.NamespaceHandlerSupport;public class MyNamespaceHandler extends NamespaceHandlerSupport {    public void init() {        registerBeanDefinitionParser("dateformat", new SimpleDateFormatBeanDefinitionParser());    }}

3.编写BeanDefinitionParser

package org.springframework.samples.xml;import org.springframework.beans.factory.support.BeanDefinitionBuilder;import org.springframework.beans.factory.xml.AbstractSingleBeanDefinitionParser;import org.springframework.util.StringUtils;import org.w3c.dom.Element;import java.text.SimpleDateFormat;public class SimpleDateFormatBeanDefinitionParser extends AbstractSingleBeanDefinitionParser {    protected Class getBeanClass(Element element) {      return SimpleDateFormat.class;    }   protected void doParse(Element element, BeanDefinitionBuilder bean) {      // this will never be null since the schema explicitly requires that a value be supplied      String pattern = element.getAttribute("pattern");      bean.addConstructorArg(pattern);      // this however is an optional property      String lenient = element.getAttribute("lenient");      if (StringUtils.hasText(lenient)) {         bean.addPropertyValue("lenient", Boolean.valueOf(lenient));      }   }}

4.钩入配置
META-INF/spring.handlers指定命名空间处理器

http\://www.mycompany.com/schema/myns=org.springframework.samples.xml.MyNamespaceHandler

META-INF/spring.schemas指定schema路径，用于schema验证（xsd放在class路径下）

http\://www.mycompany.com/schema/myns/myns.xsd=org/springframework/samples/xml/myns.xsd

5.使用扩展标签

<?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:myns="http://www.mycompany.com/schema/myns"      xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.mycompany.com/schema/myns http://www.mycompany.com/schema/myns/myns.xsd">   <!-- as a top-level bean -->   <myns:dateformat id="defaultDateFormat" pattern="yyyy-MM-dd HH:mm" lenient="true"/>   <bean id="jobDetailTemplate" abstract="true">      <property name="dateFormat">         <!-- as an inner bean -->         <myns:dateformat pattern="HH:mm MM-dd-yyyy"/>      </property>   </bean></beans>