Question

我正在尝试调整照片的大小并同步上传到服务器。我相信关键将是使流功能同步。

let str = '"This" is my "new" key "string"';
let strArray = str.split("");
let open = true;
for (let i = 0; i < strArray.length; ++i) {
    if (strArray[i] == '"') {
        if (open === true) {
            strArray[i] = '{';
        }
        else {
           strArray[i] = '}';
        }
        open = (open == true) ? false : true;
    }
}
str = strArray.join("");
console.log(str)

Answer 1

在NodeJS中执行同步操作是不好-在同步方法结束时，它会停止处理事件队列。

据我了解，您将“ 同步”命名为具有回调。

将流转换为承诺怎么样？

const downloadAndResizePhotoByUrl = (photoUrl, size) => {
  return new Promise((resolve, reject) => {

    gm(request(photoUrl))
      .resize(size[0], size[1])
      .streamFn((error, stdout, stderr) => {
        if(error) return reject(error);

        let buffer = Buffer.from('');
        stdout.on('data', data => {
          buffer = Buffer.concat([buffer, data]);
        });
        stdout.on('end', () => resolve(buffer));
        stdout.on('error', error => reject(error));
      });

  });
}

const uploadPhotoFromUrlToS3 = async (photoUrl, uploadAs, size, cb) => {
  try {

    const data = await downloadAndResizePhotoByUrl(photoUrl, size);

    uploadToServerSynchronous(
      {
        Bucket: config.s3_bucket_photos,
        Key: uploadAs,
        Body: Buffer.from(data),
        ACL: 'public-read', 
        ContentType: "image/jpeg"
      }, 
      cb
    );
  } 
  catch (error) {
    cb(error);
  } 
}

使用magicmagick同步调整大小和上传

1 个答案: