一个登陆过滤器的小例子

1. 过滤的路径要有统一的可以表示的路径，以方便模块化过滤

例如：用户模块：/user/*，信息模块：/info/*

2. 过滤器要有能排除不过滤路径的功能；

3. 实现相关的业务需要；

import java.io.IOException;

import java.util.ArrayList;

import java.util.List;

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;

import org.apache.log4j.Logger;

import org.springframework.util.StringUtils;

import com.dbdata.constant.DBDataConstants;

public class LoginFilter implements Filter {

private static final Logger logger = Logger.getLogger(LoginFilter.class);

public LoginFilter() {

}

@Override

public void init(FilterConfig filterConfig) throws ServletException {

}

@Override

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {

HttpServletRequest req = (HttpServletRequest) request;

HttpSession session = req.getSession();

HttpServletResponse resp = (HttpServletResponse) response;

String url = req.getRequestURI();

logger.info("url:" + url);

//不需要过滤的链接

List<String> excludeLinks = new ArrayList<String>();

excludeLinks.add("/dbdatamanage/admin/login/valid");

if (!excludeLinks.contains(url)) {

String user_name = (String) session.getAttribute(DBDataConstants.USER_NAME);

String user_id = (String) session.getAttribute(DBDataConstants.USER_ID);

logger.info("user_name:" + user_name);

logger.info("user_id:" + user_id);

if (StringUtils.isEmpty(user_name) || StringUtils.isEmpty(user_id)) {

resp.sendRedirect(req.getContextPath() + "/jhub/login.jsp");

return;

}

}

chain.doFilter(request, response);

}

@Override

public void destroy() {

}

}