【拦截器、过滤器实现单用户登录】

1、拦截器

package com.wkrj.interceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;

import wkrjsystem.user.bean.WkrjUser;
import wkrjsystem.wkrjlogin.service.WkrjLonginService;
//继承HandlerInterceptorAdapter 
public class Singleuserlogin extends HandlerInterceptorAdapter {
	@Autowired
	private WkrjLonginService wkrjLonginService;
	
	@Override
	public boolean preHandle(HttpServletRequest request,
			HttpServletResponse response, Object handler) throws Exception {
		String url=request.getRequestURI();
		//如果拦截到的是登录的页面的话放行
		if(url.indexOf("wkrjlogin/checkLogin")>=0||url.indexOf("wkrjlogin/login")>=0
				||url.indexOf("/img/tx.png")>0){
            return true;
        }
		//如果用户名存在放心（即登录放行）
		
		WkrjUser user = (WkrjUser) request.getSession().getAttribute("user");
		WkrjUser userDev = (WkrjUser) request.getSession().getAttribute("userDev");
		if(userDev !=null){
			
		}
		 if(user!=null){
			 String id=request.getSession().getId();
			 	String sessionid = wkrjLonginService.getSessionByUserid(user.getUser_id());
	            if(sessionid.equals(request.getSession().getId())){
	                return true;
	            } else{
	            //获取完整路径
	            	String basePath = request.getScheme() + "://" + request.getServerName() + ":"  + request.getServerPort()+request.getContextPath();
	            //判断ajax请求
	            	if("XMLHttpRequest".equals(request.getHeader("X-Requested-With"))){
	                    //告诉ajax我是重定向
	                    response.setHeader("REDIRECT", "REDIRECT");
	                    //告诉ajax我重定向的路径
	                    response.setHeader("CONTENTPATH", basePath+"/system/login.jsp");
	                    response.setStatus(HttpServletResponse.SC_FORBIDDEN);
	                    return false;
	                }else{
	                    response.sendRedirect(basePath + "/system/login.jsp");
	                    return false;
	                }
	            }
	        }
		return super.preHandle(request, response, handler);
	}
}

配置
spring-mvc.xml

<mvc:interceptors>
	<mvc:interceptor>
		<mvc:mapping path="/**"/>
		<bean id="Singleuserlogin" class="com.wkrj.interceptor.Singleuserlogin"></bean>
	</mvc:interceptor>
</mvc:interceptors> 

2、过滤器

package com.wkrj.interceptor;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;

import wkrjsystem.user.bean.WkrjUser;
import wkrjsystem.wkrjlogin.service.WkrjLonginService;



public class LoginFilter implements Filter{
	private String unauthorizedUrl = "/unauthorized.jsp";  
    private String loginUrl = "/system/login.jsp";
    @Autowired
	private JdbcTemplate jdbcTemplate;
    @Autowired
   	private WkrjLonginService wkrjLonginService;
	@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;
		//HttpServletResponse resq = (HttpServletResponse)response;
		ServletContext context = request.getServletContext();
        WebApplicationContext ctx = WebApplicationContextUtils.getWebApplicationContext(context);
        WkrjLonginService LonginService = ctx.getBean(WkrjLonginService.class);
		/*String contextPath = req.getContextPath();
        String requestURI = req.getRequestURI();
        HttpSession session = req.getSession(false);*/
		String url=req.getRequestURI();
		//如果拦截到的是登录的页面的话放行
		if(url.indexOf(loginUrl)>=0||url.indexOf("wkrjlogin/login")>=0
				){
            //return true;
			chain.doFilter(request, response);
			 return;
        }
		//如果用户名存在放心（即登录放行）
		
		WkrjUser user = (WkrjUser) req.getSession().getAttribute("user");
		WkrjUser userDev = (WkrjUser) req.getSession().getAttribute("userDev");
		if(userDev !=null){
			
		}
		 if(user!=null){
			 	String id=user.getUser_id();
			 	//Map<String, Object> user1 = jdbcTemplate.queryForMap("select * from wkrj_sys_user where user_id ='"+id+"'");
			 	String sessionid = LonginService.getSessionByUserid(id);
			 	//String sessionid=user1.get("sessionid")+"";
	            if(sessionid.equals(req.getSession().getId())){
	               // return true;
	            	chain.doFilter(request, response);
	            	 return;
	            } else{
	                request.getRequestDispatcher("/system/login.jsp").forward(req, response);
	            	//resq.sendRedirect("/system/login.jsp");
	                //return false;
	            }
	        }
	}
	@Override
	public void destroy() {
		
	}
    
	/*@Override
	protected boolean isAccessAllowed(ServletRequest arg0,
			ServletResponse arg1, Object arg2) throws Exception {
		// TODO Auto-generated method stub
		return false;
	}
	@Override
	protected boolean onAccessDenied(ServletRequest request, ServletResponse response)
			throws Exception {
		HttpServletRequest req = (HttpServletRequest)request;
		String url=req.getRequestURI();
		//如果拦截到的是登录的页面的话放行
		if(url.indexOf(loginUrl)>=0||url.indexOf(unauthorizedUrl)>=0
				){
            return true;
        }
		//如果用户名存在放心（即登录放行）
		
		WkrjUser user = (WkrjUser) req.getSession().getAttribute("user");
		WkrjUser userDev = (WkrjUser) req.getSession().getAttribute("userDev");
		if(userDev !=null){
			
		}
		 if(user!=null){
			 String id=req.getSession().getId();
			 	String sessionid = user.getSessionid();
	            if(sessionid.equals(req.getSession().getId())){
	                return true;
	            } else{
	                request.getRequestDispatcher("/system/login.jsp").forward(req, response);
	                //return false;
	            }
	        }
		return false;
	}*/
}

配置
web.xml

<filter>
	<filter-name> loginFilter</filter-name>
	<filter-class>
	com.wkrj.interceptor.LoginFilter
	</filter-class>
  </filter>
  <filter-mapping>
	<filter-name>loginFilter</filter-name>
	<url-pattern>*.jsp</url-pattern>
  </filter-mapping>