在Spring 2中整合DWR 2

前些日子看了一篇关于在Spring 2中整合DWR 2的文章《AJAX, DWR and Spring》。最近，想动手试一下，就下载其源代码回来看看，依葫芦画瓢做了一遍。在运行时，得到XML验证错误。经过一翻折腾，终于把问题解决。
Spring 2基于XML Schema的配置
众所周知，Spring 2通过XML Schema配置方式极大地简化的其配置，而且使得第三方扩展变为可能。配置如下代码所示：

< 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-2.0.xsd" >


清单1 applicationContext.xml
不知大家有没有想过spring-beans-2.0.xsd位置在那里？其实，大家可以用Eclipse打开Spring的jar包，展开META-INF，并双击打开其中的spring.schemas文件，内容如下：
http\://www.springframework.org/schema/beans/spring-beans- 2.0 .xsd = org/springframework/beans/factory/xml/spring-beans- 2.0 .xsd
http\://www.springframework.org/schema/tool/spring-tool- 2.0 .xsd = org/springframework/beans/factory/xml/spring-tool- 2.0 .xsd
http\://www.springframework.org/schema/util/spring-util- 2.0 .xsd = org/springframework/beans/factory/xml/spring-util- 2.0 .xsd
http\://www.springframework.org/schema/aop/spring-aop- 2.0 .xsd = org/springframework/aop/config/spring-aop- 2.0 .xsd
http\://www.springframework.org/schema/lang/spring-lang- 2.0 .xsd = org/springframework/scripting/config/spring-lang- 2.0 .xsd
http\://www.springframework.org/schema/tx/spring-tx- 2.0 .xsd = org/springframework/transaction/config/spring-tx- 2.0 .xsd
http\://www.springframework.org/schema/jee/spring-jee- 2.0 .xsd = org/springframework/ejb/config/spring-jee- 2.0 .xsd
http\://www.springframework.org/schema/beans/spring-beans.xsd = org/springframework/beans/factory/xml/spring-beans- 2.0 .xsd
http\://www.springframework.org/schema/tool/spring-tool.xsd = org/springframework/beans/factory/xml/spring-tool- 2.0 .xsd
http\://www.springframework.org/schema/util/spring-util.xsd = org/springframework/beans/factory/xml/spring-util- 2.0 .xsd
http\://www.springframework.org/schema/aop/spring-aop.xsd = org/springframework/aop/config/spring-aop- 2.0 .xsd
http\://www.springframework.org/schema/lang/spring-lang.xsd = org/springframework/scripting/config/spring-lang- 2.0 .xsd
http\://www.springframework.org/schema/tx/spring-tx.xsd = org/springframework/transaction/config/spring-tx- 2.0 .xsd
http\://www.springframework.org/schema/jee/spring-jee.xsd = org/springframework/ejb/config/spring-jee- 2.0 .xsd
清单2 spring.schemas
从以上的文件中，可以看出XML Sechema文件在类包中位置。
DWR 2.0 RC 2中的XML Schema文件
根据上面的描述，我打开DWR的jar包中spring.schemas文件，内容如下：
http\://www.directwebremoting.org/schema/spring-dwr- 2.0 .xsd = org/directwebremoting/spring/spring-dwr- 2.0 .xsd
然后，按照上面的路径打开spring-dwr-2.0.xsd文件，内容如下：


< xsd:schema xmlns ="http://www.directwebremoting.org/schema/spring-dwr"
xmlns:xsd ="http://www.w3.org/2001/XMLSchema"
targetNamespace ="http://www.directwebremoting.org/schema/spring-dwr"
elementFormDefault ="qualified"
attributeFormDefault ="unqualified" >


清单3 spring-dwr-2.0.xsd
文件spring-dwr-2.0.xsd告诉我们，其名称空间应为“http://www.directwebremoting.org/schema/spring-dwr”，所以我们在配置Spring 2时，应使用以上的名称空间，如下面的代码片段所示：

< beans xmlns ="http://www.springframework.org/schema/beans"
xmlns:dwr ="http://www.directwebremoting.org/schema/spring-dwr"
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
http://www.directwebremoting.org/schema/spring-dwr http://www.directwebremoting.org/schema/spring-dwr-2.0.xsd" >
< dwr:configuration >
< dwr:convert class ="net.blogjava.max.pws.domain.Album" type ="bean" >
< dwr:exclude method ="photos" />

< dwr:convert class ="net.blogjava.max.pws.domain.Photo" type ="bean" >
< dwr:exclude method ="original, poster, thumb, full, album" />


< bean id ="ajaxFacade"
class ="net.blogjava.max.pws.web.ajax.AjaxFacade" >
< dwr:remote javascript ="AjaxFacade" />
< property name ="personalWebSite" ref ="personalWebSite" />


清单3 ajaxContext.xmlWEB-INF/web.xml配置
通过上面的配置，我们可以省去dwr.xml配置，不过在web.xml配置dwr的Servlet时，要使用新的Servlet类。配置代码片段如下：
< servlet >
< servlet-name > dwr
< servlet-class > org.directwebremoting.spring.DwrSpringServlet
< init-param >
< param-name > debug
< param-value > true

< load-on-startup > 1

< servlet-mapping >
< servlet-name > dwr
< url-pattern > /dwr/*

清单4 web.xml总结
通过在Spring 2整合DWR 2配置，可以集中管理应用程序的配置，从一定程度上解决JavaEE开发中的配置文件泛滥的问题。