让OpenSessionInViewFilter更灵活的过滤URL 博客分类： Hibernate ServletJSPWebSpringHibernate

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;
	}


	@Override
	protected 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OpenSessionInViewFilter
			super.doFilterInternal(request, response, filterChain);
		}else{//不符合，则不应用
			filterChain.doFilter(request, response);
		}
	}


	@Override
	public 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。