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• 1.
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。
