ajax 请求无法重定向

package com.wjz.demo;

import java.io.IOException;

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;

public class XMLHttpRequestTest implements Filter {

    @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 resp = (HttpServletResponse) response;
        resp.setHeader("Access-Control-Allow-Origin","*");
        resp.setHeader("Access-Control-Allow-Credentials","true");
        redirect(req,resp);
    }

    private void redirect(HttpServletRequest req,HttpServletResponse resp) throws IOException {
        if("XMLHttpRequest".equals(req.getHeader("X-Requested-With"))){
            //前端需要判断是否是重定向
            resp.setHeader("REDIRECT","true");
            //需要重定向的路径
            resp.setHeader("CONTENTPATH","http:127.0.0.1:8080/login.do");
            resp.setStatus(HttpServletResponse.SC_FORBIDDEN);
        }else{
            resp.sendRedirect("http:127.0.0.1:8080/login.do");
        }
    }

    @Override
    public void destroy() {
        
    }

}

$.ajaxSetup({ 
        complete:function(jqxhr,status){
            if("true" == jqxhr.getResponseHeader("REDIRECT")){ //若HEADER中含有REDIRECT说明后端想重定向，
                var win = window;
                while(win != win.top){
                    win = win.top;
                }
                win.location.href = jqxhr.getResponseHeader("CONTENTPATH");//将后端重定向的地址取出来,使用win.location.href去实现重定向的要求
            }
        }
    });