登陆控制过滤器(Java版)

package com.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;

public class LoginFilter implements Filter {

String loginPage;

String homePage;

public void destroy() {

}

public void doFilter(ServletRequest request, ServletResponse response,

FilterChain chain) throws IOException, ServletException { // 获得在下面代码中要是的request,response,session对象

HttpServletRequest servletRequest = (HttpServletRequest) request;

HttpServletResponse servletResponse = (HttpServletResponse) response;

HttpSession session = servletRequest.getSession();

// 获得用户请求的uri

String requri = servletRequest.getRequestURI();

System.out.println(requri);

// 应用程序的名字

String contextPath = servletRequest.getContextPath();

System.out.println(contextPath);

// 访问网页的名字

String uri = requri.substring(contextPath.length());

System.out.println(uri);

if (loginPage.equals(uri)) {

String logon = request.getParameter("action");

if (!"logon".equals(logon)) {

chain.doFilter(servletRequest, servletResponse);

} else {

String name = servletRequest.getParameter("name");

String password = servletRequest.getParameter("password");

if ("admin".equals(name) && "admin".equals(password)) {

session.setAttribute("isLogin", "true");

session.setAttribute("name", name);

String olduri = servletRequest.getParameter("uri");

if (null != olduri && !"".equals(olduri)) {

RequestDispatcher dis = servletRequest

.getRequestDispatcher(olduri);

dis.forward(servletRequest, servletResponse);

} else {

RequestDispatcher dis = servletRequest

.getRequestDispatcher(homePage);

dis.forward(servletRequest, servletResponse);

}

} else {

String origin = servletRequest.getParameter("uri");

if (null != origin && !"".equals(origin)) {

servletRequest.setAttribute("uri", origin);

}

RequestDispatcher dis = servletRequest

.getRequestDispatcher(loginPage);

dis.forward(servletRequest, servletResponse);

}

}

} else {

// 判断是否登录

String isLogin = (String) session.getAttribute("isLogin");

// 如果已经登录，直接显示网页内容

if ("true".equals(isLogin)) {

chain.doFilter(servletRequest, servletResponse);

} else {

// 否则跳回登录页

servletRequest.setAttribute("uri", uri);

RequestDispatcher dis = servletRequest

.getRequestDispatcher(loginPage);

dis.forward(servletRequest, servletResponse);

}

}

}

public void init(FilterConfig config) throws ServletException {

//从web.xml中读取信息。

loginPage = config.getInitParameter("login");

homePage = config.getInitParameter("home");

}

}