14-下载图片

下载文件的方式有好多种

1.download 直接下载

这个文件信息应该存数据库 我们这儿演示就写死 了

import { Controller, Post, UseInterceptors, UploadedFile, Get, Res } from '@nestjs/common';
import { UploadService } from './upload.service';
import { FileInterceptor, FilesInterceptor } from '@nestjs/platform-express'
import type { Response } from 'express'
import {join} from 'path'
@Controller('upload')
export class UploadController {
  constructor(private readonly uploadService: UploadService) { }
  @Post('album')
  @UseInterceptors(FileInterceptor('file'))
  upload(@UploadedFile() file) {
    console.log(file, 'file')
    return '峰峰35岁憋不住了'
  }
  @Get('export')
  downLoad(@Res() res: Response) {
    const url = join(__dirname,'../images/1662894316133.png')
    // res
    // console.log(url)
    res.download(url)
    // return  true
  }
}

2.使用文件流的方式下载

可以使用 compressing 把他压缩成一个 zip 包

import {zip} from 'compressing' npm 下载

  @Get('stream')
  async down (@Res() res:Response) {
    const url = join(__dirname,'../images/1662894316133.png')
    const tarStream  = new zip.Stream()
    await tarStream.addEntry(url)
    //固定语法
    res.setHeader('Content-Type', 'application/octet-stream');

    res.setHeader(
      'Content-Disposition',
      `attachment; filename=xiaoman`,
    );
    //此时是二进制文件，不能直接查看，需要前端做解析
    tarStream.pipe(res)

  }

前端接受流，并解析

增强安全性，可以进行一些操作

const useFetch = async (url: string) => {
  const res = await fetch(url).then(res => res.arrayBuffer())
  console.log(res)
  const a = document.createElement('a')
  a.href = URL.createObjectURL(new Blob([res],{
    // type:"image/png"
  }))
  a.download = 'xiaman.zip'
  a.click()
}

const download = () => {
  useFetch('http://localhost:3000/upload/stream')
}

下载完是一个压缩包