1 在web.xml中配置filter(要放在字符集过滤器之后，否则字符过滤会失效)

      
             
      
       LoginFilter
              
      
       LoginFilter
              
      
       com.xxx.common.LoginFilter
       
      
             
      
       LoginFilter
              
      
       /*
       
     

2.拦截器类(登录，注册，静态文件.js.css等不进行过滤,放过去)

package com.xxx.common;import java.io.IOException;import java.io.Writer;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 net.sf.json.JSONObject;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.ApplicationContext;import org.springframework.stereotype.Component;import org.springframework.web.context.support.WebApplicationContextUtils;import com.xxx.entity.User;import com.xxx.service.LoginService;import com.xxx.util.CommonUtil;public class LoginFilter implements Filter {    private LoginService loginService;    public LoginService getLoginService() {        return loginService;    }    public void setLoginService(LoginService loginService) {        this.loginService = loginService;    }    public LoginFilter() {    }    /**     * 初始化     */    public void init(FilterConfig config) throws ServletException {        ServletContext context = config.getServletContext();        ApplicationContext ctx = WebApplicationContextUtils                .getWebApplicationContext(context);        loginService = (LoginService) ctx.getBean(LoginService.class);    }    public void destroy() {        loginService = null;    }    /**     * 登录拦截     */    public void doFilter(ServletRequest req, ServletResponse res,            FilterChain chain) throws IOException, ServletException {        HttpServletRequest httpRequest = (HttpServletRequest) req;        HttpServletResponse httpResponse = (HttpServletResponse) res;        String path = CommonUtil.getRequestURL(httpRequest);                if (path.indexOf("/tologin") != -1 || path.indexOf("/login") != -1                || path.indexOf("/include") != -1) {            chain.doFilter(req, res);        } else {            User user = loginService.getCurrentUser();            if (user == null) {                boolean isAjaxRequest = isAjaxRequest(httpRequest);                if (isAjaxRequest) {                    httpResponse.setCharacterEncoding("UTF-8");                    Writer out = httpResponse.getWriter();                    JSONObject jsonObj = new JSONObject();                    jsonObj.put("success", false);                    jsonObj.put("code", "noLogin");                    jsonObj.put("message", "请您先登录系统!");                    out.write(jsonObj.toString());                    out.flush();                    out.close();                } else {                    httpResponse.sendRedirect("/项目路径/Login/tologin");                }            } else {                chain.doFilter(req, res);            }        }    }    /**     * 判断是否为Ajax请求     *     * @param request     *            HttpServletRequest     * @return 是true, 否false     */    public static boolean isAjaxRequest(HttpServletRequest request) {        String requestType = request.getHeader("X-Requested-With");        return requestType != null && "XMLHttpRequest".equals(requestType);    }}