springmvc之filter的基本用法

1. 建filter类

package com.ssm.blog.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.web.filter.OncePerRequestFilter;

/**
 * OncePerRequestFilter 
 *		确保一个请求只经过一个filter,而不需要重复执行
 * @author huangdb
 *
 */
public class SessionFilter extends OncePerRequestFilter{

	@Override
	protected void doFilterInternal(HttpServletRequest request,HttpServletResponse response, FilterChain filterChain)
			throws ServletException, IOException {
			
			System.out.println("====测试Filter功能====拦截用户登陆====");
			  
        	String[] notFilter = new String[] { "login.jsp"}; // 不过滤的uri
        	String strUri = request.getRequestURI() ;  
        	
        	if( strUri.indexOf("admin")!=-1 && request.getSession().getAttribute("userSession")==null ){
        		//进入后台,必须先登陆
        		if( strUri.indexOf("login.action")==-1 && strUri.indexOf("index.action")==-1 ){//点击的是登陆页面
        			response.sendRedirect("login.action") ;
            	}else{
            		filterChain.doFilter(request, response);//不执行过滤,继续执行操作
            		return ;
            	}
        	}else{
        		filterChain.doFilter(request, response);//不执行过滤,继续执行操作
        		//filterChain.doFilter(new MyFilter((HttpServletRequest)request), response);//调用下一个filter
        		return ;
        	}
	}

}

2. 在web.xml中对filter进行配置

	
    	sessionFilter  
    	com.ssm.blog.filter.SessionFilter  
	  
	  
	    sessionFilter  
	    *.action