设置表头

//form形式private sendHttpRequest(url : string, params : any): Promise
    
      {    let Interface_Address : string = "";  //接口地址    let body = new URLSearchParams();    // let commonUser = this.cookieService.getObject('loginUserId');    // console.info(commonUser)    for(let key in params){        body.set(key, params[key]);        //console.log(key);        //console.log(params[key]);    }    let headers = new Headers({'Content-Type' : 'application/x-www-form-urlencoded;charset=UTF-8'});    // headers.set("Cookies", this.cookieService.getObject('loginUserId'));    //继承登录的cookie withCredentials: true    let options = new RequestOptions({headers : headers, withCredentials: true});    return this.http               .post( Interface_Address+url , body , options)               .toPromise()               .then( this.extractData );}