ajax异步session值不唯一 总是改变 解决办法

public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {

        HttpServletResponse res = (HttpServletResponse) servletResponse;

        HttpServletRequest request=(HttpServletRequest)servletRequest;

        res.setContentType("textml;charset=UTF-8");

        res.setHeader("Access-Control-Allow-Origin", request.getHeader("Origin"));

        res.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");

        res.setHeader("Access-Control-Max-Age", "0");

        res.setHeader("Access-Control-Allow-Headers", "Origin, No-Cache, X-Requested-With, If-Modified-Since, Pragma, Last-Modified, Cache-Control, Expires, Content-Type, X-E4M-With,userId,token");

        res.setHeader("Access-Control-Allow-Credentials", "true");

        res.setHeader("XDomainRequestAllowed","1");

        filterChain.doFilter(servletRequest,servletResponse);

    }

在ajax 请求是也要加相应的东西

$.ajax({

url:url,

//加上这句话

xhrFields: {

           withCredentials: true

       },

       crossDomain: true,

success:function(result){

alert("test");

},

error:function(){

}

});

这样我们再跨域测试的时候，就会发现我们的sessionId是一样的了，这样就实现了跨域并且保证在同一个session下。