java前后端交互解决跨域问题

        //后台跨域处理        //EG:"Access-Control-Allow-Origin", "*"         response.addHeader("Access-Control-Allow-Origin", "http://127.0.0.1:8020");         response.addHeader("Access-Control-Allow-Methods", "GET, POST, DELETE, PUT");        response.addHeader("Access-Control-Allow-Headers", "Content-Type, Cookie");        response.setHeader("Access-Control-Allow-Credentials", "true");        //前端跨域处理        function GetAjaxInfo(url,data,obj){            var defaultsParam = {                async:true,                type:"POST",                callback:function(res){                },                error:function(){                    common.alert("系统异常");                }            }            $.extend(defaultsParam, obj);            var callbackRes = {};                $.ajax({                    type : defaultsParam.type,                    url : baseURL+url,                    **xhrFields**:{//这句话是必须加的这个地方加这个后台必须指定url地址不能用*                        withCredentials:true                    },                    datatype : 'json',                    data:data,                    async:defaultsParam.async,                    success : function(res) {                        defaultsParam.callback(res);                    },                    error : function(){                        defaultsParam.error();//系统异常默认处理                    }                });                return callbackRes;}