??? 最近做了个一个项目，需要配置权限访问，就随便网上查了下资料，总结了下，这三种常用配置方式。首先明白这点filter主要拦截url地址，interceptor拦截访问的action。

一、jsp 配置filter 过滤器，

???? （1）配置过滤器，过滤url地址

????? web.xml 中配置

??????

    <!-- 配置过滤器，控制jsp目录下的访问权限 -->
    <filter> 
        <filter-name>perimission filter</filter-name> 
        <filter-class> 
           com.flower.filter.PermissionFilter
        </filter-class> 
    </filter> 
    <filter-mapping> 
        <filter-name>perimission filter</filter-name> 
        <url-pattern>/jsp/*</url-pattern> 
    </filter-mapping>

??? filter配置如下

???

package com.flower.filter;

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.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * 配置filter过滤器，判断用户是否登陆，没有登陆跳转到index.jsp
 * @author Administrator
 *
 */
public class PermissionFilter implements Filter{

	public void destroy() {
		
	}

	public void doFilter(ServletRequest arg0, ServletResponse arg1,
			FilterChain chain) throws IOException, ServletException {
		
		HttpServletRequest request=(HttpServletRequest) arg0;
		
		HttpSession session=request.getSession();
		HttpServletResponse response=(HttpServletResponse) arg1;
		

		
		//判断后台是否登陆，如果没登陆跳转到index.jsp
		if(session.getAttribute("falgAdmin")==null||((Integer)session.getAttribute("falgAdmin")!=2)){
			
			System.out.println("用户未登陆，跳转到index.jsp");
			response.sendRedirect(request.getContextPath());
			return ;
		}
		
		System.out.println("用户登陆");
		chain.doFilter(arg0, arg1); //如果登陆直接向下执行
	}

	public void init(FilterConfig filterConfig) throws ServletException {
		
	}

}

?（2）、配置字符过滤器

? web.xml 配置如下

 <filter>  
    <filter-name>CharacterEncodingFilter</filter-name>  
    <filter-class>com.test.filter.CharacterEncodingFilter</filter-class>    
       <init-param>  
         <param-name>encoding</param-name>  
         <param-value>utf-8</param-value>  
     </init-param>  
   </filter>  
  <filter-mapping>     
     <filter-name>CharacterEncodingFilter</filter-name>  
     <url-pattern>/*</url-pattern>  
   </filter-mapping> 

?

filter配置如下

package com.test.filter;

 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;  
   
 public class CharacterEncodingFilter implements Filter {  
   
     protected FilterConfig filterConfig = null;       
     protected String encoding = "";  
   
     public void destroy() {  
         filterConfig = null;  
         encoding = null;  
     }  
   
     public void doFilter(ServletRequest request, ServletResponse response,  
             FilterChain filterChain) throws IOException, ServletException {  
         if (encoding != null) { 
        	 //设置request和response的编程格式，注意两个都要设，若没设response的
             //charset，则在输出页面会显示乱码。
             request.setCharacterEncoding(this.encoding); 
             response.setContentType("text/html;charset=utf-8");
         }  
         //继续执行下一个过滤器
         filterChain.doFilter(request, response);  
     }  
   
     public void init(FilterConfig filterConfig) throws ServletException {  
         this.filterConfig = filterConfig;  
        this.encoding = filterConfig.getInitParameter("encoding");  
        
     }  
 }