问在jhipster中实现下载按钮

EN

yarn add file-saver
yarn add xlsx

import { Injectable } from '@angular/core';
import * as FileSaver from 'file-saver';
import * as XLSX from 'xlsx';

const EXCEL_TYPE = 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet;charset=UTF-8';
const EXCEL_EXTENSION = '.xlsx';

@Injectable()
export class ExcelService {

  constructor() { }

public exportAsExcelFile(json: any[], excelFileName: string): void {
    const worksheet: XLSX.WorkSheet = XLSX.utils.json_to_sheet(json);
    excelFileName = this.convertToSlug(excelFileName);

    const range = XLSX.utils.decode_range(worksheet['!ref']);
    for (let C = range.s.r; C <= range.e.r; ++C) {
        const address = XLSX.utils.encode_col(C) + '1'; // <-- first row, column number C
        if (!worksheet[address]) { continue; }
        worksheet[address].v = worksheet[address].v.toUpperCase();
    }

    const workbook: XLSX.WorkBook = { Sheets: { 'data': worksheet }, SheetNames: ['data'] };
    // const excelBuffer: any = XLSX.write(workbook, { bookType: 'xlsx', type: 'buffer' });
    const excelBuffer: any = XLSX.write(workbook, { bookType: 'xlsx', type: 'array' });

    this.saveAsExcelFile(excelBuffer, excelFileName);
}

private saveAsExcelFile(buffer: any, fileName: string): void {
    const data: Blob = new Blob([buffer], {
        type: EXCEL_TYPE
    });
    const date =  new Date();

    FileSaver.saveAs(data, fileName + '_export_' + this.dateToYMD(date) + '_' + date.getTime() + EXCEL_EXTENSION);
}

dateToYMD(date: Date) {
    const d = date.getDate();
    const m = date.getMonth() + 1; // Month from 0 to 11
    const y = date.getFullYear();
    return '' + y + '-' + (m <= 9 ? '0' + m : m) + '-' + (d <= 9 ? '0' + d : d);
}

convertToSlug(Text) {
    return Text
        .toLowerCase()
        .replace(/ /g, '-')
        .replace(/[^\w-]+/g, '')
        ;
}
}

 entities: IEntities[];
  this.excelService.exportAsExcelFile(entities, 'download');