如何在构造函数Angular 2上使用Async调用注入服务

这是问题:我有一个服务在构造函数中发出HTTP请求:

    constructor(public http: Http, public geolocation: Geolocation) {
        this.http = http;
        this.geolocation = geolocation;
        //Http request... this will set variable forecast of the class when complete.
        this.getForecast(16);
    }

    constructor(public connector: ApiConnector) {
         this.forecast = connector.forecast;
    }

@Component({
    selector: 'app',
    directives: [MainForecast, DailyForecast],
    template: `
        
        
    `,
})