现代Web应用中，文件上传是一个常见的需求。前端通过HTTP POST请求将文件发送到后端服务器，后端接收并处理这些文件。Python作为后端开发语言，结合一些Web框架，可以轻松实现文件上传功能。本文将介绍如何使用Flask和FastAPI这两个流行的Python Web框架来接收前端上传的文件，并提供多个实际案例。
1. 使用Flask接收上传文件
Flask是一个轻量级的Python Web框架，适合快速开发和原型设计。我们首先介绍如何使用Flask接收前端上传的文件。
案例1：基本文件上传
首先，我们需要安装Flask：
pip install Flask然后，创建一个简单的Flask应用来接收文件上传：
from flask import Flask, request, redirect, url_for
import os
app = Flask(__name__)
UPLOAD_FOLDER = 'uploads'
# 确保上传文件夹存在
if not os.path.exists(UPLOAD_FOLDER):
os.makedirs(UPLOAD_FOLDER)
app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER
@app.route('/')
def index():
return '''
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Upload File</title>
</head>
<body>
<h1>Upload File</h1>
<form method="POST" action="/upload" enctype="multipart/form-data">
<input type="file" name="file">
<input type="submit" value="Upload">
</form>
</body>
</html>
'''
@app.route('/upload', methods=['POST'])
def upload_file():
if 'file' not in request.files:
return "No file part"
file = request.files['file']
if file.filename == '':
return "No selected file"
if file:
filepath = os.path.join(app.config['UPLOAD_FOLDER'], file.filename)
file.save(filepath)
return f"File uploaded successfully: {file.filename}"
if __name__ == '__main__':
app.run(debug=True)案例2：文件类型和大小校验
为了确保上传的文件符合要求，我们可以添加文件类型和大小的验证。
from werkzeug.utils import secure_filename
ALLOWED_EXTENSIONS = {'txt', 'pdf', 'png', 'jpg', 'jpeg', 'gif'}
MAX_CONTENT_LENGTH = 16 * 1024 * 1024 # 16 MB
app.config['MAX_CONTENT_LENGTH'] = MAX_CONTENT_LENGTH
def allowed_file(filename):
return '.' in filename and \
filename.rsplit('.', 1)[1].lower() in ALLOWED_EXTENSIONS
@app.route('/upload', methods=['POST'])
def upload_file():
if 'file' not in request.files:
return "No file part"
file = request.files['file']
if file.filename == '':
return "No selected file"
if file and allowed_file(file.filename):
filename = secure_filename(file.filename)
filepath = os.path.join(app.config['UPLOAD_FOLDER'], filename)
file.save(filepath)
return f"File uploaded successfully: {filename}"
else:
return "File type not allowed or file too large"2. 使用FastAPI接收上传文件
FastAPI是一个现代、快速的Web框架，适合构建高性能的API。使用FastAPI接收文件上传也非常简单。
安装FastAPI和Uvicorn
pip install fastapi uvicorn案例1：基本文件上传
创建一个FastAPI应用来接收文件上传：
from fastapi import FastAPI, File, UploadFile
import os
app = FastAPI()
UPLOAD_FOLDER = 'uploads'
# 确保上传文件夹存在
if not os.path.exists(UPLOAD_FOLDER):
os.makedirs(UPLOAD_FOLDER)
@app.post("/upload/")
async def upload_file(file: UploadFile = File(...)):
filepath = os.path.join(UPLOAD_FOLDER, file.filename)
with open(filepath, "wb") as buffer:
buffer.write(await file.read())
return {"filename": file.filename}
if __name__ == '__main__':
import uvicorn
uvicorn.run(app, host="0.0.0.0", port=8000)案例2：文件类型和大小校验
在FastAPI中，我们可以使用Pydantic定义校验规则。
from fastapi import FastAPI, File, UploadFile, HTTPException
from pydantic import BaseModel
import os
app = FastAPI()
UPLOAD_FOLDER = 'uploads'
ALLOWED_EXTENSIONS = {'txt', 'pdf', 'png', 'jpg', 'jpeg', 'gif'}
MAX_CONTENT_LENGTH = 16 * 1024 * 1024 # 16 MB
# 确保上传文件夹存在
if not os.path.exists(UPLOAD_FOLDER):
os.makedirs(UPLOAD_FOLDER)
def allowed_file(filename):
return '.' in filename and \
filename.rsplit('.', 1)[1].lower() in ALLOWED_EXTENSIONS
@app.post("/upload/")
async def upload_file(file: UploadFile = File(...)):
if not allowed_file(file.filename):
raise HTTPException(status_code=400, detail="File type not allowed")
if len(await file.read()) > MAX_CONTENT_LENGTH:
raise HTTPException(status_code=400, detail="File too large")
filepath = os.path.join(UPLOAD_FOLDER, file.filename)
with open(filepath, "wb") as buffer:
buffer.write(await file.read())
return {"filename": file.filename}
if __name__ == '__main__':
import uvicorn
uvicorn.run(app, host="0.0.0.0", port=8000)结语
在Python中接收前端POST上传的文件可以使用多种框架来实现，Flask和FastAPI是其中的两个流行选择。本文介绍了如何使用这两个框架实现基本的文件上传功能，并进行了文件类型和大小的校验。希望这些案例能帮助你在实际项目中更好地处理文件上传需求。