类型“ HttpResponse <any>”上不存在属性“ blob”

Question

我正在尝试将angular 4升级到5，为此我不得不从@ angular / common / http导入HttpClient，HttpResponse和HttpHeaders，而不是从'@ angular / http'导入Http，Response，Headers，RequestOptions，ResponseContentType。 ;

但是在我之前的代码中，我使用的是let headers = new Headers（）;我用let headers = new HttpHeaders（）替换了它；和responseType：ResponseContentType.Blob替换为responseType：'blob'

现在在方法getData（）res.blob（）中说，类型'HttpResponse'上不存在属性'blob'。

ExcelDownload(_getRequestUrl: string) {
            let headers = new HttpHeaders();
            headers.append('Content-Type', 'application/json' ); 
            return this.http.get(this.getUrlWithEmpId(_getRequestUrl), {
                headers : headers,
                responseType: 'blob'
        }).map(response => this.getData(response)) .catch(error => this.handleError(error));
        }   
        public getData(res: HttpResponse<any>) {
            let headers = res.headers;
            let contentType = headers.get('Content-Type');
            var blob;
            try {
                if(contentType === 'pdf' || contentType === 'application/pdf') {
                    //chek this
                    blob = new Blob([res.blob()], { type: "application/pdf"});
                } else {
                    //check thi
                    blob = new Blob([res.blob()], { type: "application/vnd.ms-excel"});
                }
            }
            catch (e) {
              
            }
            return blob;
        }