让OpenSessionInViewFilter更灵便的过滤URL

让OpenSessionInViewFilter更灵活的过滤URL
OpenSessionInViewFilter能很方便的处置视图显示的时候Hibernate的Lazy load 问题，但受制于filter-mapping的url-pattern，如果要精细控制过滤的url,则会导致web.xml文件filter-mapping元素大增，而且url-pattern匹配模式仅限于路径匹配模式、扩展匹配模式及详细匹配模式（参考http://foxty.iteye.com/blog/39332）。

如何更灵活的控制OpenSessionInViewFilter需要过滤的URL？
这里给出一种代价较小，但更灵活的方式：

package com.your.servlet.filter;import java.io.IOException;import javax.servlet.FilterChain;import javax.servlet.ServletException;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.springframework.orm.hibernate3.support.OpenSessionInViewFilter;import org.springframework.util.AntPathMatcher;/** *  * @author llade * @version 1.0 * Creation date: Oct 9, 2008 10:31:32 AM */public class OpenSessionInViewFilterDelegate extends OpenSessionInViewFilter {protected String[] mappings = new String[]{};private AntPathMatcher antPathMatcher = new AntPathMatcher();private boolean filterURI(String uriWithoutContextPath){for (int i = 0; i < mappings.length; i++) {if(antPathMatcher.match(mappings[i],uriWithoutContextPath)){if(logger.isDebugEnabled()){logger.debug("matched,pattern:"+mappings[i]+",uri:"+uriWithoutContextPath);}return true;}}if(logger.isDebugEnabled()){logger.debug("not matched,uri:"+uriWithoutContextPath);}return false;}public String[] getMappings() {return mappings;}public void setMappings(String[] mappings) {this.mappings = mappings;}@Overrideprotected void doFilterInternal(HttpServletRequest request,HttpServletResponse response, FilterChain filterChain)throws ServletException, IOException {String uri = request.getRequestURI();String contextPath = request.getContextPath();String uriWithoutContextPath = uri.substring(contextPath.length());if(this.filterURI(uriWithoutContextPath)){//符合过滤规则.则应用OpenSessionInViewFiltersuper.doFilterInternal(request, response, filterChain);}else{//不符合，则不应用filterChain.doFilter(request, response);}}@Overridepublic void afterPropertiesSet() throws ServletException {for (int i = 0; i < mappings.length; i++) {mappings[i] = mappings[i].trim();}super.afterPropertiesSet();}}

web.xml配置：

 <filter><filter-name>openSessionInViewFilterDelegate</filter-name><filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class></filter><filter-mapping><filter-name>openSessionInViewFilterDelegate</filter-name><url-pattern>/*</url-pattern></filter-mapping>

这里解释一下，org.springframework.web.filter.DelegatingFilterProxy会找到和<filter-name>名字相同的<bean>来处理符合filter-mapping的url，真正的url过滤放在了OpenSessionInViewFilterDelegate ,所以此处使用匹配所有路径。

spring配置：

<bean id="openSessionInViewFilterDelegate" class="com.your.servlet.filter.OpenSessionInViewFilterDelegate">     <property name="mappings">       <list>         <value>/viewlist/**.jsp</value>         <value>/do/**.jsp</value>         <value>/another/*/*.jsp</value>       </list>     </property>   </bean>

这里使用了ant路径方式，*匹配单层路径，**匹配任何多层路径。而且配置也没那么复杂了。 1 楼 freeroy 2012-05-18   呃～既然都是spring环境，可不直接使用DelegatingFilterProxy呢～用Ant表达式就OK了

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