from flask import Flask, send_file, Response, send_from_directory
import io

app = Flask(__name__)


def file_send(file_path):  # 发送大文件可以该方法
    with open(file_path, 'rb') as f:
        while 1:
            data = f.read(20 * 1024 * 1024)  # 每次读取20M
            if not data:
                break
            yield data


@app.route("/download1")
def download1():
    return send_file('test.xlsx', as_attachment=True, attachment_filename='test.xlsx')  # 或使用下行代码
    # return send_from_directory('./', 'test.xlsx', as_attachment=True)


@app.route("/download2")
def download2():
    with open('test.xlsx', 'rb') as f:
        stream = f.read()
    response = Response(stream, content_type='application/octet-stream')
    response.headers['Content-disposition'] = 'attachment; filename=test.xlsx'
    return response


@app.route("/download3")
def download3():
    file = io.BytesIO()  # 本地没有文件，将内容写入内存发送
    file.write("你好".encode('utf-8'))
    file.seek(0)
    return send_file(file, as_attachment=True, attachment_filename="hi.txt")  # 用下面3行代码也可

    # response = Response(file, content_type='application/octet-stream')
    # response.headers['Content-disposition'] = 'attachment; filename=test.xlsx'
    # return response


@app.route("/download4")
def download4():
    file_name = "MEM3.mp4"
    response = Response(file_send(file_name), content_type='application/octet-stream')
    response.headers["Content-disposition"] = f'attachment; filename={file_name}'
    return response


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