signonfilter.java

JSP高级程序员网络开发源代码

package com.jspdev.ch8;

import javax.servlet.FilterChain;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;
import javax.servlet.FilterConfig;
import javax.servlet.http.HttpSession;

public class SignonFilter implements Filter
{
	String LOGIN_PAGE="login_signon.jsp";
	protected FilterConfig filterConfig;
	
	//过滤处理的方法
	public void doFilter(final ServletRequest req,final ServletResponse res,FilterChain chain)throws IOException,ServletException
	{
		 HttpServletRequest hreq = (HttpServletRequest)req;
         HttpServletResponse hres = (HttpServletResponse)res;
         HttpSession session = hreq.getSession();
         String isLogin="";
         try
         {
         	isLogin=(String)session.getAttribute("isLogin");        
         
			 if(isLogin.equals("true"))
			 {
			 	System.out.println("在SignonFilter中验证通过");
			 	//验证成功，继续处理
			 	chain.doFilter(req,res);
			 }
			 else
			 {
			 	//验证不成功，让用户登录。
			 	hres.sendRedirect(LOGIN_PAGE);	 		 	
			 	System.out.println("被SignonFilter拦截一个未认证的请求");
			 }
		 }
         catch(Exception e)
         {         
         	e.printStackTrace();
         }
		 	
	}
	
	public void setFilterConfig(final FilterConfig filterConfig)
	{
		this.filterConfig=filterConfig;
	}
    
    //销毁过滤器
	public void destroy()
	{
		this.filterConfig=null;
	}
	 /**
     *初始化过滤器,和一般的Servlet一样，它也可以获得初始参数。
     */
    public void init(FilterConfig config) throws ServletException {
        this.filterConfig = config;       
    }
	
}