filter 过滤器

<!--配置过滤器-->
	<filter>
		<filter-name>MergeFilter</filter-name>
		<filter-class>com.commons.filter.MergeFilter</filter-class>
	</filter>

	<!--映射过滤器-->
	<filter-mapping>
		<filter-name>MergeFilter</filter-name>
		<url-pattern>/selfhelp/*</url-pattern>
		<dispatcher>REQUEST</dispatcher>  
		<dispatcher>FORWARD</dispatcher>
		<dispatcher>ERROR</dispatcher>
		<dispatcher>INCLUDE</dispatcher>
	</filter-mapping>

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import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

public class MergeFilter implements Filter {

	@Override
	public void destroy() {

	}

	@Override
	public void doFilter(final ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		request.setCharacterEncoding("UTF-8");
		response.setCharacterEncoding("UTF-8");
		response.setContentType("text/html;charset=UTF-8");
        
        chain.doFilter(new HttpServletRequestWrapper((HttpServletRequest) request) {  
            @Override  
            public String getRequestURI() {  
            	String url = ((HttpServletRequest) request).getRequestURI();
                if (url.contains("/selfhelp") && !url.contains("/selfhelp/selfhelp")) {
        			url = url.replace("/selfhelp", "/selfhelp/selfhelp");
        		}
            	return url;
            }  
        }, response);
	}

	@Override
	public void init(FilterConfig arg0) throws ServletException {

	}

}

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用<jsp:include page="success.jsp"></jsp:include> 就可以过滤了， 

jsp中include[1]有两种形式,分别是 
<%@ include file=” ”%> 
<jsp:include page=” ” flush=”true”/> 
前者是指令元素、后者是行为元素。通常当应用程序中所有的页面的某些部分（例如标题、页脚和导航栏）都相同的时候，就可以考虑用include。<%@ include file=” ”%>,jsp的include指令元素读入指定页面的内容。并把这些内容和原来的页面融合到一起。(这个过程是在翻译阶段:也就是jsp被转化成servlet的阶段进行的。) 
include与jsp:include主要有两个方面的不同; 
一:执行时间上: 
<%@ include file=”relativeURI”%> 是在翻译阶段执行 
<jsp:include page=”relativeURI” flush=”true” /> 在请求处理阶段执行. 
二:引入内容的不同: 
<%@ include file=”relativeURI”%> 
引入静态文本(html,jsp),在JSP页面被转化成servlet之前和它融和到一起. 
<jsp:include page=”relativeURI” flush=”true” />引入执行页面或servlet所生成的应答文本. 
另外在两种用法中file和page属性都被解释为一个相对的URI.如果它以斜杠开头,那么它就是一个环境相关的路径.将根据赋给应用程序的URI的前缀进行解释,如果它不是以斜杠开头,那么就是页面相关的路径,就根据引入这个文件的页面所在的路径进行解释

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filter 过滤器

原文：http://knight-black-bob.iteye.com/blog/2248026