发送multipart/form-data内容类型请求

POST /upload HTTP/1.1
Host: example.com
Content-Type: multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW

------WebKitFormBoundary7MA4YWxkTrZu0gW
Content-Disposition: form-data; name="username"

John
------WebKitFormBoundary7MA4YWxkTrZu0gW
Content-Disposition: form-data; name="avatar"; filename="photo.jpg"
Content-Type: image/jpeg

<二进制文件数据>
------WebKitFormBoundary7MA4YWxkTrZu0gW--

const formData = new FormData();
formData.append('username', 'John');
formData.append('avatar', fileInput.files[0]); // 假设是文件输入框

fetch('/upload', {
  method: 'POST',
  body: formData, // 自动设置 Content-Type 和 boundary
});

const express = require('express');
const multer = require('multer');
const upload = multer({ dest: 'uploads/' });

app.post('/upload', upload.single('avatar'), (req, res) => {
  console.log(req.body.username); // 文本字段
  console.log(req.file); // 文件信息
  res.send('Upload success');
});

from flask import Flask, request

app = Flask(__name__)

@app.route('/upload', methods=['POST'])
def upload():
    username = request.form.get('username')
    file = request.files['avatar']
    file.save(f'uploads/{file.filename}')
    return 'Upload success'