错误：无法解析客户服务的所有参数：(？)

Question

在这里我创建了两个 ts 文件，一个是服务，另一个是服务中的常规，我实现了一些服务并在通用 ts 文件中调用，同时我的页面正在加载其贯穿错误，如 NoProviderError.BaseError [作为构造函数]

服务网

@Component({
    templateUrl: "../../template/customer/customer.html",
    providers: [CustomerService]
})
    Url = "http://localhost:54873/Api/Home/GetEmp"
        public constructor(private _http: Http) {
        }
        getEmpData() {
            debugger;
            return this._http.get(this.Url).map(this.extractData).catch(this.handleError);
        }

组件.ts

@Component({
    templateUrl: "../../template/customer/customer.html",
   providers: [CustomerService]
})
@Injectable()
    export class CustomerComponent {
        Url = "http://localhost:54873/Api/Home/GetEmp"
        getfun: string;
        constructor(private _HttpService: CustomerService) { }
        getData() {
            return this._HttpService.getEmpData().subscribe(data => this.getfun = JSON.stringify(data), error => alert('This is error...'),
                  () => console.log());
        }

Answer 1

你不能在

service.ts 文件中有@Component，它应该如下所示，

@Injectable()
export class CustomerService {
    public constructor(private _http: Http) {
    }
    getEmpData(): Observable<Employee[]> {
        debugger;
        return this._http.get(this.Url).map(this.extractData).catch(this.handleError);
    }
    private extractData(res: Response) {
        let body = res.json();
        // this.Employees = res.json
        return body.data || {};
    }
    private handleError(error: Response | any) {
        // In a real world app, you might use a remote logging infrastructure
        let errMsg: string;
        if (error instanceof Response) {
            const body = error.json() || '';
            const err = body.error || JSON.stringify(body);
            errMsg = `${error.status} - ${error.statusText || ''} ${err}`;
        } else {
            errMsg = error.message ? error.message : error.toString();
        }
        console.error(errMsg);
        return Observable.throw(errMsg);
    }
}