如何用Flask写一个文件（图片）上传下载的API？

文件上传完整代码

#!/usr/bin/python
# -*- coding: UTF-8 -*-
from flask import request, jsonify, send_from_directory, abort
from werkzeug.utils import secure_filename
from flask import Flask, render_template, jsonify, request
import time
import os
import base64

app = Flask(__name__)
UPLOAD_FOLDER = 'upload'
app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER
basedir = os.path.abspath(os.path.dirname(__file__))
ALLOWED_EXTENSIONS = set(['txt', 'png', 'jpg', 'xls', 'JPG', 'PNG', 'xlsx', 'gif', 'GIF'])


# 用于判断文件后缀
def allowed_file(filename):
    return '.' in filename and filename.rsplit('.', 1)[1] in ALLOWED_EXTENSIONS


# # 用于测试上传，稍后用到
# @app.route('/test/upload')
# def upload_test():
#     return render_template('upload.html')


@app.route("/api/download/<filename>", methods=['GET'])
def download(filename):
    if request.method == "GET":
        if os.path.isfile(os.path.join('upload', filename)):
            return send_from_directory('upload', filename, as_attachment=True)
        abort(404)


# 上传文件
@app.route('/api/upload', methods=['POST'], strict_slashes=False)
def api_upload():
    file_dir = os.path.join(basedir, app.config['UPLOAD_FOLDER'])
    if not os.path.exists(file_dir):
        os.makedirs(file_dir)
    f = request.files['myfile']  # 从表单的file字段获取文件，myfile为该表单的name值
    if f and allowed_file(f.filename):  # 判断是否是允许上传的文件类型
        fname = secure_filename(f.filename)
        print fname
        ext = fname.rsplit('.', 1)[1]  # 获取文件后缀
        unix_time = int(time.time())
        new_filename = str(unix_time) + '.' + ext  # 修改了上传的文件名
        f.save(os.path.join(file_dir, new_filename))  # 保存文件到upload目录
        token = base64.b64encode(new_filename)
        print token
        return jsonify({"code": 0, "errmsg": "上传成功", "token": token, "fileName": "/api/download/" + new_filename})
    else:
        return jsonify({"code": 1001, "errmsg": "上传失败"})


if __name__ == '__main__':
    app.run(debug=True)

新建一个upload.html测试

<form id="form1" method="post" action="http://127.0.0.1:5000/api/upload" enctype="multipart/form-data">
    <div>
        <input id="File1" type="file" name="myfile"/>
        <input type="submit">提交</input>
    </div>
</form>

如何下载？

上传完成后会返回fileName字段，用域名加fileName即可访问图片

如 http://127.0.0.1:5000/api/download/xxx.png

有一个坑值得注意，如果你的文件名是全中文，Flask是无法识别的（Flask底层源码设计的问题），处理方式也很简单，自己最好做好容错处理，重新定义一个名字