express+multer上传图片打开乱码问题及解决

const fs=require('fs')
router.post('/imageUpload',upload.single('avatar'),function (req, res) {
    console.log(req.file)
    //获取文件后缀名
    var appendName=req.file.originalname.split('.')[1]
    //fs重命名文件，第一个参数为上传文件绝对路径，第二个参数为相对路径
    //第三个参数可选
    fs.rename(req.file.path,`tmp/uploads/${req.file.filename}.${appendName}`,function (err) {
        if (err) throw err
    })
    res.json({msg:'success'})
})

<div class="upload-file btn btn-sm btn-primary mb-2">
  <span><i class="fa fa-upload"></i> Upload</span>
  <input type="file" class="btn btn-sm btn-primary mb-2" (change)="fileChange($event, topic)" placeholder="Upload file" accept=".csv,.xls">
</div>

fileChange(event, topic) {
  this.topic = topic;
  const fileList: FileList = event.target.files;
  const file: File = fileList[0];
  const formData: FormData = new FormData();
  formData.append('_id', topic._id);
  formData.append('file', file, file.name);
  this.topicService.uploadMark(formData).subscribe((res) => {
    this.topic.marks = res;
    this.toast.setMessage('item import successfully.', 'success');
  }, error => console.log(error));
}

uploadMark(fileData: FormData): Observable<any> {
  return this.http.post('/api/upload', fileData);
}

export default function setRoutes(app) {
  const router = express.Router();
// file uplaod
router.route('/upload').post(uploadCtrl.uploadFile);
// Apply the routes to our application with the prefix /api
app.use('/api', router);
}

npm install multer --save
import * as path from 'path';
import * as multer from 'multer';
import TopicService from '../services/topic';
export default class UploadCtrl {
  uploadFile = (req, res) => {
    const topicService = new TopicService();
    // 获取上传文件
    const uploading = multer({
      dest: path.join(__dirname, '../public/uploads'),
    }).single('file'); // 这里的file是formData.append('file', file, file.name)里的名称
    uploading(req, res, (err) => {
      if (err) {
        return console.error(err);
      }
      const topicId = req.body._id;
      const uploadFile = req.file;
      // 保存数据
      const save = async () => {
        const markList = await topicService.parseMark(uploadFile.path);
        const db = await topicService.saveDB(topicId, markList);
        return {
          markList: markList,
          db: db,
        };
      };
      save().then((result) => {
        res.status(200).json(result.markList);
      }, error => {
        console.error(error);
      });
    });
  }
}

npm install iconv-lite --save
import * as iconv from 'iconv-lite';
import * as Buffer from 'bufferhelper';
export default class IconvHelper {
  /**
   * 用于文件上传的转码
   * @param fileStr
   * @returns {string}
   */
  static iconv2utf8 = (fileStr) => {
    return iconv.decode(fileStr, 'gbk');
  }
  /**
   * 用于文件下载的转码
   * @param fileStr
   * @returns {NodeBuffer}
   */
  static iconv2gbk = (fileStr) => {
    return iconv.encode(fileStr, 'gbk');
  }
}

parseMark = (filePath) => {
  return new Promise((resolve, reject) => {
    // 读取文件内容
    fs.readFile(filePath, (error, data) => {
      if (error) {
        return reject(error);
      }
      const text = IconvHelper.iconv2utf8(data);
      const markList = [];
      // 将文件按行拆成数组
      text.split(/\r?\n/).forEach((line, index) => {
        const arr = line.split(',');
        if (index > 0 && arr[0]) {
          markList.push({
            userId: arr[0],
            username: arr[1],
            donePageCount: arr[2],
            areaCount: arr[4],
            name: arr[6],
          });
        }
      });
      resolve(markList);
    });
  });
}

res.setHeader('Content-disposition', `attachment; filename='${result.name}-member.csv'`);
res.setHeader('Content-type', 'text/csv; charset=GBK');
res.end(IconvHelper.iconv2gbk(content));

const msExcelBuffer = Buffer.concat([
  new Buffer('\xEF\xBB\xBF', 'binary'),
  new Buffer(IconvHelper.iconv2gbk(content))
]);

res.end(IconvHelper.iconv2gbk(content));