使用servlet制作简单登陆filter过滤器

水深无声 2024-04-19 12:28 60阅读 0赞

package cn.zsyy.admin;
    
    import java.io.IOException;
    import java.util.ArrayList;
    import java.util.HashMap;
    
    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.annotation.WebFilter;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpSession;
    
    import cn.zsyy.db.Dao;
    
    /**
     * Servlet Filter implementation class AdminFilter
     */
    @WebFilter("/admin/*")
    public class AdminFilter implements Filter {
    
        /**
         * Default constructor. 
         */
        public AdminFilter() {
            // TODO Auto-generated constructor stub
        }
    
    	/**
    	 * @see Filter#destroy()
    	 */
    	public void destroy() {
    		// TODO Auto-generated method stub
    	}
    
    	/**
    	 * @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
    	 */
    	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
    		System.out.println("-------admin  filter-------");
    		//获取路径信息
    		HttpServletRequest req = (HttpServletRequest) request;
    		String servletPath = req.getServletPath();
    		
    		System.out.println(servletPath);
    		//通过路径匹配放行，注册页面和登录页面。其余页面一律需要判断登录信息和权限
    		if(servletPath.equals("/admin/register")||servletPath.equals("/admin/login")) {
    			chain.doFilter(request, response);
    		}else {
    			//获取session对象
    			HttpSession session = req.getSession();
    			if(session.getAttribute("username")!=null) {
    				//以登录即放行
    				//chain.doFilter(request, response);
    				String username =(String) session.getAttribute("username");
    				//查找此用户的用户类型
    				String sqlStr = "select * from user where username = ?";
    				String[] params = {username};
    				ArrayList<HashMap<String, Object>> res = Dao.query(sqlStr, params);
    				HashMap<String, Object> user = res.get(0);
    				//根据是否有访问权限，如果有直接访问，如果没有，告知没有访问权限，并且跳转至登录页
    				System.out.println(user.get("userType"));
    				if(user.get("userType").equals("admin")) {
    					chain.doFilter(request, response);
    					//System.out.println("servlet path:"+req.getServletPath());
    				}else {
    					req.setAttribute("httpUrl", "/admin/login");
    					req.setAttribute("info", "您没有权限访问！请联系管理人员。即将跳转至登录页面。");
    					req.setAttribute("title", "访问失败！");
    					req.getRequestDispatcher("/admin/info.jsp").forward(req, response);
    				}
    				
    			}else {
    				//如果没有登录，那么跳转至登录页面
    				req.setAttribute("httpUrl", "/admin/login");
    				req.setAttribute("info", "您尚未登录！即将跳转至登录页面。");
    				req.setAttribute("title", "未登录！");
    				req.getRequestDispatcher("/admin/info.jsp").forward(req, response);
    			}
    		}
    		
    	}
    
    	/**
    	 * @see Filter#init(FilterConfig)
    	 */
    	public void init(FilterConfig fConfig) throws ServletException {
    		// TODO Auto-generated method stub
    	}
    
    }

以上为代码 小心空指针异常的处理 要不然会报错