flask简明教程🏆

May 21 2020

搭建Flask

最小flask应用

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from flask import Flask
app = Flask(__name__)

@app.route("/")
def hello():
    return "<h1 style='color:blue'>Hello There!</h1>"

if __name__ == "__main__":
    app.run(host='0.0.0.0')

简单GET/POST请求

GET

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@app.route("/hello", methods=['GET'])
def hello_get():
  return 'hello'

POST

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@app.route("/hello", methods=['POST'])
def hello_post():
  img = request.files['img'] # 接受文件
  img.save('./save.jpg')
  return 'success'

return 类型

return类型支持字符串/json/元组/Response对象/重定向类型redirect。还可以附带状态码

返回字符串

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return 'str'

json

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from flask import jsonify
...
@app.route("/hello", methods=['GET'])
def hello_get():
  return jsonify({'code':200, 'msg': 'hello'})

元组,元组内容包括三个参数,response(响应体),status_code(状态码),headers(响应头)

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@app.route("/hello")
def hello():
    json_dict = {
    	'msg': 'hello'，
		  'code': 200
		}
    data = json.dumps(json_dict)
    return data, 200, {"ContentType":"application/json"}

Response对象

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from flask import make_response
...

@app.route("/hello")
def hello():
  response=make_response('say hello!')

  return response

重定向类型redirect

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from flask import redirect
...
@app.route("/hello")
def hello():

  return redirect('http://bouseng.com')

附带状态码

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@app.route("/hello")
def hello():
  return 'hello', 200

request

导入request

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from flask import request

POST表单数据：request.form

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# 获取单个字段的值：request.form[字段名]
name = request.form['name']

# 获取所有表单数据：request.form.to_dict()
all_value = request.form.to_dict()

GET请求参数：request.args

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# 获取某个字段的值：request.args.get(字段名)
name = request.args.get('name')
获取所有GET请求参数
all_args = request.args

接收POST图片处理

转为base64

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import base64

@app.route('/pic2base64', methods=['POST'])
def pic2base64():
    pic = request.files['pic']
    base64_data = base64.b64encode(pic.read())

转为cv2格式

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import cv2
import numpy as np

@app.route('/pic2cv', methods=['POST'])
def pic2base64():
    pic = request.files['pic']
    cv_image = cv2.imdecode(np.fromstring(pic.read(), np.uint8), cv2.IMREAD_COLOR)

转为PIL格式

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from PIL import Image

@app.route('/pic2pil', methods=['POST'])
def pic2base64():
    pic = request.files['pic']
    pil_image = Image.open(pic.stream).convert('RGB')

解决跨域

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app = Flask(__name__)

def after_request(response):
    response.headers['Access-Control-Allow-Origin'] = '*'
    response.headers['Access-Control-Allow-Methods'] = 'PUT,GET,POST,DELETE'
    response.headers['Access-Control-Allow-Headers'] = 'Content-Type,Authorization'
    response.headers['X-Content-Type-Options'] = 'nosniff'
    return response

app.after_request(after_request)

blueprint

合理使用blueprint，将程序各api模块化，使得程序不会臃肿不堪。

项目结构

———— main.py

———— applications

————————app1.py

main.py

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import sys
sys.path.append('applications')

from app1 import app_name

app = Flask(__name__)
app.register_blueprint(app_name, url_prefix='/app_name')

app1.py

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from flask import Blueprint

app_name = Blueprint('app_name', __name__)

@app_name.route('/')
def hello():
  return 'hello blueprint'

flask