问角度2等待，直到变量设置完毕

EN

@Injectable()
export class interaction{
private host: string="";
private port: string = "";
constructor(private http: Http) {

    this.http.get("/interaction.json").subscribe((data: Response) => {
        this.host = data.json().host;
        this.port = data.json().port;

    });  
}

interact(data:Request): Promise<Response>{       
    return this.http.post("http://" + this.host + ":" + this.port, data)
        .toPromise()
        .then(data => data.json() as Response)
        .catch(this.handleError);
}