myfilter.java

oa rar it is the jsp

package com.accp.oa.control.filter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.RequestDispatcher;
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;

/*
 * 此过滤器用于
 * 控制没有登录的
 * 人员进入系统的
 * 相应页面
 */
public class MyFilter implements Filter {
	private FilterConfig config;

	public void destroy() {

	}

	/*
	 * 在此方法中进行处理
	 * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)
	 */
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		//获得HttpServletRequest和HttpServletResponse对象
		HttpServletRequest re = (HttpServletRequest) request;
		HttpServletResponse res = (HttpServletResponse)response;
		//获理HttpSession对象
		HttpSession session = re.getSession(false);
		if (session != null) {//Session不为空
			if (session.getAttribute("username") != null) {//用户登录成功
				chain.doFilter(request, response);
			} else {//用户没登录成功
				res.sendRedirect(re.getContextPath()+"/login.jsp");	
			}
		} else {//session为空
			res.sendRedirect(re.getContextPath()+"/login.jsp");
		}

	}

	public void init(FilterConfig config) throws ServletException {
		this.config = config;
	}

}