如何将图像从 url 加载到 nodejs 的缓冲区中

how to load an image from url into buffer in nodejs

提问by CodeMonkeyB

I am new to nodejs and am trying to set up a server where i get the exif information from an image. My images are on S3 so I want to be able to just pass in the s3 url as a parameter and grab the image from it.

我是 nodejs 的新手，正在尝试设置一个服务器，我可以从图像中获取 exif 信息。我的图像在 S3 上，所以我希望能够将 s3 url 作为参数传入并从中获取图像。

I am u using the ExifImage project below to get the exif info and according to their documentation:

我正在使用下面的 ExifImage 项目来获取 exif 信息并根据他们的文档：

"Instead of providing a filename of an image in your filesystem you can also pass a Buffer to ExifImage."

“您还可以将缓冲区传递给 ExifImage，而不是在文件系统中提供图像的文件名。”

How can I load an image to the buffer in node from a url so I can pass it to the ExifImage function

如何将图像从 url 加载到节点中的缓冲区，以便我可以将其传递给 ExifImage 函数

ExifImage Project: https://github.com/gomfunkel/node-exif

ExifImage 项目：https: //github.com/gomfunkel/node-exif

Thanks for your help!

谢谢你的帮助！

回答by Dan Kohn

Try setting up request like this:

尝试像这样设置请求：

var request = require('request').defaults({ encoding: null });
request.get(s3Url, function (err, res, body) {
      //process exif here
});

Setting encodingto nullwill cause request to output a buffer instead of a string.

设置encoding为null将导致请求输出缓冲区而不是字符串。

回答by Yehonatan

I was able to solve this only after reading that encoding: nullis requiredand providing it as an parameter to request.

我可以只读取后，解决这个encoding: null是必需的，并提供其作为参数来请求。

This will download the image from url and produce a buffer with the image data.

这将从 url 下载图像并生成包含图像数据的缓冲区。

Using the request library -

使用请求库 -

const request = require('request');

let url = 'http://website.com/image.png';
request({ url, encoding: null }, (err, resp, buffer) => {
     // Use the buffer
     // buffer contains the image data
     // typeof buffer === 'object'
});

Note: omitting the encoding: nullwill result in an unusable string and not in a buffer. Buffer.from won't work correctly too.

注意：省略encoding: null将导致无法使用的字符串，而不是在缓冲区中。Buffer.from 也不会正常工作。

This was tested with Node 8

这是用 Node 8 测试的

回答by Timothy Strimple

Use the requestlibrary.

使用请求库。

request('<s3imageurl>', function(err, response, buffer) {
    // Do something
});

Also, node-image-headersmight be of interest to you. It sounds like it takes a stream, so it might not even have to download the full image from S3 in order to process the headers.

此外，您可能对node-image-headers感兴趣。听起来它需要一个流，因此它甚至可能不必从 S3 下载完整图像来处理标头。

Updated with correct callback signature.

更新了正确的回调签名。

回答by DeppWang

Use the axios:

使用axios：

const response = await axios.get(url,  { responseType: 'arraybuffer' })
const buffer = Buffer.from(response.data, "utf-8")