避免发回 Base64 编码的图像(多个图像 + 大文件 + 大编码字符串 = 性能非常慢)。我强烈建议创建一个仅处理图像上传和任何其他图像相关的获取/发布/放置/删除请求的微服务。将其与主应用程序分开。
例如:
- 我使用 multer 创建图像缓冲区
- 然后使用 Sharp 或 fs 保存图像(取决于文件类型)
- 然后我将文件路径发送到我的控制器以保存到我的数据库中
- 然后,前端在尝试访问时会发出 GET 请求:
http://localhost:4000/uploads/timestamp-randomstring-originalname.fileext
简单来说,我的微服务就像一个专门用于图像的 CDN。
例如,用户发送一个post请求到http://localhost:4000/api/avatar/create
一些 FormData:
它首先经过一些 Express 中间件:
库/middlewares.js
...
app.use(cors({credentials: true, origin: "http://localhost:3000" })) // allows receiving of cookies from front-end
app.use(morgan(`tiny`)); // logging framework
app.use(multer({
limits: {
fileSize: 10240000,
files: 1,
fields: 1
},
fileFilter: (req, file, next) => {
if (!/\.(jpe?g|png|gif|bmp)$/i.test(file.originalname)) {
req.err = `That file extension is not accepted!`
next(null, false)
}
next(null, true);
}
}).single(`file`))
app.use(bodyParser.json()); // parses header requests (req.body)
app.use(bodyParser.urlencoded({ limit: `10mb`, extended: true })); // allows objects and arrays to be URL-encoded
...etc
然后,点击avatars
route:
路线/avatars.js
app.post(`/api/avatar/create`, requireAuth, saveImage, create);
然后它通过一些用户身份验证,然后通过我的saveImage
中间件:
服务/saveImage.js
const createRandomString = require('../shared/helpers');
const fs = require("fs");
const sharp = require("sharp");
const randomString = createRandomString();
if (req.err || !req.file) {
return res.status(500).json({ err: req.err || `Unable to locate the requested file to be saved` })
next();
}
const filename = `${Date.now()}-${randomString}-${req.file.originalname}`;
const filepath = `uploads/${filename}`;
const setFilePath = () => { req.file.path = filepath; return next();}
(/\.(gif|bmp)$/i.test(req.file.originalname))
? fs.writeFile(filepath, req.file.buffer, (err) => {
if (err) {
return res.status(500).json({ err: `There was a problem saving the image.`});
next();
}
setFilePath();
})
: sharp(req.file.buffer).resize(256, 256).max().withoutEnlargement().toFile(filepath).then(() => setFilePath())
如果文件已保存,则会发送一个req.file.path
to my create
控制器。这将作为文件路径和图像路径保存到我的数据库中(avatarFilePath
or /uploads/imagefile.ext
保存用于删除目的,并且avatarURL
or [http://localhost:4000]/uploads/imagefile.ext
保存并用于前端GET请求):
控制器/avatars.js(我使用的是 Postgres,但你可以用 Mongo 代替)
create: async (req, res, done) => {
try {
const avatarurl = `${apiURL}/${req.file.path}`;
await db.result("INSERT INTO avatars(userid, avatarURL, avatarFilePath) VALUES ($1, $2, $3)", [req.session.id, avatarurl, req.file.path]);
res.status(201).json({ avatarurl });
} catch (err) { return res.status(500).json({ err: err.toString() }); done();
}
然后当前端尝试访问uploads
文件夹通过<img src={avatarURL} alt="image" />
or <img src="[http://localhost:4000]/uploads/imagefile.ext" alt="image" />
,它由微服务提供:
库/server.js
const express = require("express");
const path = app.get("path");
const PORT = 4000;
//============================================================//
// EXPRESS SERVE AVATAR IMAGES
//============================================================//
app.use(`/uploads`, express.static(`uploads`));
//============================================================//
/* CREATE EXPRESS SERVER */
//============================================================//
app.listen(PORT);
记录请求时的样子:
19:17:54 INSERT INTO avatars(userid, avatarURL, avatarFilePath) VALUES ('08861626-b6d0-11e8-9047-672b670fe126', 'http://localhost:4000/uploads/1536891474536-k9c7OdimjEWYXbjTIs9J4S3lh2ldrzV8-android.png', 'uploads/1536891474536-k9c7OdimjEWYXbjTIs9J4S3lh2ldrzV8-android.png')
POST /api/avatar/create 201 109 - 61.614 ms
GET /uploads/1536891474536-k9c7OdimjEWYXbjTIs9J4S3lh2ldrzV8-android.png 200 3027 - 3.877 ms
用户在成功 GET 请求后看到的内容: