大文件上传

前端代码（文件名需要判断是否存在  -  ，存在会后台出错）

axios

import axios from "axios";

const baseURL = 'http://localhost:3001';

export const uploadFile = (url, formData, onUploadProgress = () => { }) => {
  return axios({
    method: 'post',
    url,
    baseURL,
    headers: {
      'Content-Type': 'multipart/form-data'
    },
    data: formData,
    onUploadProgress
  });
}

export const mergeChunks = (url, data) => {
  return axios({
    method: 'post',
    url,
    baseURL,
    headers: {
      'Content-Type': 'application/json'
    },
    data
  });
}

后端代码

const router = require('koa-router')()
const koaBody = require('koa-body')
const fs = require('fs')
const path = require('path')

router.prefix('/file')
const outputPath = './src/server/resources/'
// 上传请求
router.post(
  '/upload',
  // 处理文件 form-data 数据
  koaBody({
    multipart: true,
    formidable: {
      uploadDir: outputPath,
      onFileBegin: (name, file) => {
        console.log(name)
        const [filename, fileHash, index] = name.split('-');
        const dir = path.join(outputPath, filename);
        // 保存当前 chunk 信息，发生错误时进行返回
        currChunk = {
          filename,
          fileHash,
          index
        };

        // 检查文件夹是否存在如果不存在则新建文件夹
        if (!fs.existsSync(dir)) {
          fs.mkdirSync(dir);
        }

        // 覆盖文件存放的完整路径
        file.path = `${dir}/${fileHash}-${index}`;
        console.log(file.path)
      },
      onError: (error) => {
        app.status = 400;
        app.body = { code: 400, msg: "上传失败", data: currChunk };
        return;
      },
    },
  }),
  // 处理响应
  async (ctx) => {
    ctx.set("Content-Type", "application/json");
    ctx.body = JSON.stringify({
      code: 2000,
      message: 'upload successfully！'
    });
  });
// 合并请求
router.post('/mergeChunks', async (ctx) => {
  const { filename, size } = ctx.request.body;
  // 合并 chunks
  await mergeFileChunk(path.join(outputPath, '_' + filename), filename, size);

  // 处理响应
  ctx.set("Content-Type", "application/json");
  ctx.body = JSON.stringify({
    data: {
      code: 2000,
      filename,
      size,
　　　 path:`/src/server/resources/_${filename}`

    },
    message: 'merge chunks successful！'
  });
});

// 通过管道处理流 
const pipeStream = (path, writeStream) => {
  return new Promise(resolve => {
    const readStream = fs.createReadStream(path);
    readStream.pipe(writeStream);
    readStream.on("end", () => {
      fs.unlinkSync(path);
      resolve();
    });
  });
}

// 合并切片
const mergeFileChunk = async (filePath, filename, size) => {
  const chunkDir = path.join(outputPath, filename);
  
  const chunkPaths = fs.readdirSync(chunkDir);

  if (!chunkPaths.length) return;

  // 根据切片下标进行排序，否则直接读取目录的获得的顺序可能会错乱
  chunkPaths.sort((a, b) => a.split("-")[1] - b.split("-")[1]);
  console.log("chunkPaths = ", chunkPaths);

  await Promise.all(
    chunkPaths.map((chunkPath, index) =>
      pipeStream(
        path.resolve(chunkDir, chunkPath),
        // 指定位置创建可写流
        fs.createWriteStream(filePath, {
          start: index * size,
          end: (index + 1) * size
        })
      )
    )
  );

  // 合并后删除保存切片的目录
  fs.rmdirSync(chunkDir);
};

module.exports = router