一:flask的背景介绍
Flask是一个基于Python开发并且依赖jinja2模板和Werkzeug WSGI服务的一个微型框架,对于Werkzeug本质是Socket服务端,其用于接收http请求并对请求进行预处理,然后触发Flask框架,开发人员基于Flask框架提供的功能对请求进行相应的处理,并返回给用户,如果要返回给用户复杂的内容时,需要借助jinja2模板来实现对模板的处理,即:将模板和数据进行渲染,将渲染后的字符串返回给用户浏览器。
“微”(micro) 并不表示你需要把整个 Web 应用塞进单个 Python 文件(虽然确实可以 ),也不意味着 Flask 在功能上有所欠缺。微框架中的“微”意味着 Flask 旨在保持核心简单而易于扩展。Flask 不会替你做出太多决策——比如使用何种数据库。而那些 Flask 所选择的——比如使用何种模板引擎——则很容易替换。除此之外的一切都由可由你掌握。如此,Flask 可以与您珠联璧合。
默认情况下,Flask 不包含数据库抽象层、表单验证,或是其它任何已有多种库可以胜任的功能。然而,Flask 支持用扩展来给应用添加这些功能,如同是 Flask 本身实现的一样。众多的扩展提供了数据库集成、表单验证、上传处理、各种各样的开放认证技术等功能。Flask 也许是“微小”的,但它已准备好在需求繁杂的生产环境中投入使用。
二:基本功能使用
1.补充:学习flask首先要了解装饰器的使用方式
a:不带参数的装饰器
1 定义一个装饰器函数:
2 def wrapper(func):
3 def inner(*args, **kwargs):
4 return func(*args, **kwargs)
5 return inner
6
7 用装饰器wrapper函数装饰index函数
8 @wrapper
9 def index(request):
10 pass
11
12 说明:执行@wrapper装饰器等价于:index = wrapper(index),返回值是inner
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b:带参数的装饰器
1 定义一个带参数的装饰器函数:
2 def route(option):
3 def inner(func,*args, **kwargs):
4 url_map[option['path']] = func
5 return inner
6
7 用route函数装饰index函数,并传入参数
8 @route({'path':'/index'})
9 def index(request):
10
11 说明:
12 1.首先会执行route函数,将对应的参数{'path':'/index'}传入,得到route函数的返回值inner
13 2.执行@inner等价于:inner = inner(index),此时:inner函数中的func = index;*args, **kwarg里面的参数值等于我们传入的值{'path':'/index'},因为是参数是字典的格式,因此是通过**kwargs传入的。
14 3.执行url_map[option['path']] = func,等价于下面的路由关系
15 url_map = {
16 '/index': index
17 }
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c:设置元信息
1 mport functools
2
3 def wapper(func):
4
5 @functools.wraps(func) # 帮助我们设置函数的元信息
6 def inner(*args,**kwargs):
7 return func(*args,**kwargs)
8
9 return inner
10
11 @wapper
12 def f1():
13 pass
14
15 @wapper
16 def f2():
17 pass
18
19 print(f1.__name__)
20 print(f2.__name__)
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2.三大python主流的框架对比:
Django:重武器,内部包含了非常多组件:ORM、Form、ModelForm、缓存、Session、中间件、信号等...
Flask:短小精悍,内部没有太多组件。第三方组件非常丰富。路由比较特殊:基于装饰器来实现,但是究其本质还是通过add_url_rule来实现。
Tornado:异步非阻塞框架(node.js)
3.安装:pip3 install flask
4.本质:Werkzeug WSGI
1 werkzeug示例:
2 from werkzeug.wrappers import Request, Response
3 @Request.application
4 def hello(request):
5 return Response('Hello World!')
6
7 if __name__ == '__main__':
8 from werkzeug.serving import run_simple
9 run_simple('localhost', 4000, hello)
10
11 wsgiref示例:
12 from wsgiref.simple_server import make_server
13 def runserver(environ, start_response):
14 start_response('200 OK', [('Content-Type', 'text/html')])
15 return [bytes('<h1>Hello, web!</h1>',encoding='utf-8'), ]
16
17 if __name__ == '__main__':
18 # obj = WSGIHandler()
19 httpd = make_server('', 8000, runserver)
20 httpd.serve_forever()
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本质的本质:Werkzeug本质是Socket服务端
1 import socket
2
3 def handle_request(client):
4 buf = client.recv(1024)
5 client.send("HTTP/1.1 200 OK\r\n\r\n")
6 client.send("Hello, Seven")
7
8 def main():
9 sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
10 sock.bind(('localhost',8000))
11 sock.listen(5)
12
13 while True:
14 connection, address = sock.accept()
15 handle_request(connection)
16 connection.close()
17
18 if __name__ == '__main__':
19 main()
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5.基本使用
1 from flask import Flask
2
3 # 实例化Flask对象app
4
5 app = Flask(__name__)
6
7 # 设置路由关系
8
9 {
10
11 '/':index
12
13 }
14
15 @app.route("/")
16
17 def hello_world():
18 return "hello world"
19 if __name__=="__main__":
20 app.run()
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6.配置文件
1 flask中的配置文件是一个flask.config.Config对象(继承字典),默认配置为:
2 {
3 'DEBUG': get_debug_flag(default=False), 是否开启Debug模式
4 'TESTING': False, 是否开启测试模式
5 'PROPAGATE_EXCEPTIONS': None,
6 'PRESERVE_CONTEXT_ON_EXCEPTION': None,
7 'SECRET_KEY': None,
8 'PERMANENT_SESSION_LIFETIME': timedelta(days=31),
9 'USE_X_SENDFILE': False,
10 'LOGGER_NAME': None,
11 'LOGGER_HANDLER_POLICY': 'always',
12 'SERVER_NAME': None,
13 'APPLICATION_ROOT': None,
14 'SESSION_COOKIE_NAME': 'session',
15 'SESSION_COOKIE_DOMAIN': None,
16 'SESSION_COOKIE_PATH': None,
17 'SESSION_COOKIE_HTTPONLY': True,
18 'SESSION_COOKIE_SECURE': False,
19 'SESSION_REFRESH_EACH_REQUEST': True,
20 'MAX_CONTENT_LENGTH': None,
21 'SEND_FILE_MAX_AGE_DEFAULT': timedelta(hours=12),
22 'TRAP_BAD_REQUEST_ERRORS': False,
23 'TRAP_HTTP_EXCEPTIONS': False,
24 'EXPLAIN_TEMPLATE_LOADING': False,
25 'PREFERRED_URL_SCHEME': 'http',
26 'JSON_AS_ASCII': True,
27 'JSON_SORT_KEYS': True,
28 'JSONIFY_PRETTYPRINT_REGULAR': True,
29 'JSONIFY_MIMETYPE': 'application/json',
30 'TEMPLATES_AUTO_RELOAD': None,
31 }
32
33 方式一:
34 app.config['DEBUG'] = True
35
36 PS: 由于Config对象本质上是字典,所以还可以使用app.config.update(...)
37
38 方式二:
39 app.config.from_pyfile("python文件名称")
40 如:
41 settings.py
42 DEBUG = True
43
44 app.config.from_pyfile("settings.py")
45
46 app.config.from_envvar("环境变量名称")
47 环境变量的值为python文件名称名称,内部调用from_pyfile方法
48
49
50 app.config.from_json("json文件名称")
51 JSON文件名称,必须是json格式,因为内部会执行json.loads
52
53 app.config.from_mapping({'DEBUG':True})
54 字典格式
55
56 一般的情况下使用对象的情况较多
57 app.config.from_object("python类或类的路径")
58
59 app.config.from_object('pro_flask.settings.TestingConfig')
60
61 settings.py
62
63 class Config(object):
64 DEBUG = False
65 TESTING = False
66 DATABASE_URI = 'sqlite://:memory:'
67
68 class ProductionConfig(Config):
69 DATABASE_URI = 'mysql://user@localhost/foo'
70
71 class DevelopmentConfig(Config):
72 DEBUG = True
73
74 class TestingConfig(Config):
75 TESTING = True
76
77 PS: 从sys.path中已经存在路径开始写
78
79
80 PS: settings.py文件默认路径要放在程序root_path目录,如果instance_relative_config为True,则就是instance_path目录
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代码示例:
写一个setting.py的文件用来项目所需要的配置:
1 class Config(object):
2 DEBUG = False
3 TESTING = False
4 DATABASE_URI = 'sqlite://:memory:'
5
6 # 生产环境
7 class ProductionConfig(Config):
8 DATABASE_URI = 'mysql://user@localhost/foo'
9
10 #开发环境
11 class DevelopmentConfig(Config):
12 DEBUG = True
13
14 #测试环境
15 class TestingConfig(Config):
16 TESTING = True
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使用:
1 from flask import Flask
2
3 app = Flask(__name__)
4 app.debug = True
5 app.secret_key = "asdfasdf"
6
7 # 通过app.confgi.from_object
8 app.config.from_object("settings.DevelopmentConfig")
9
10 @app.route('/')
11 def index():
12 return 'Hello World!'
13
14 if __name__ == '__main__':
15 app.run()
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7.路由系统
- @app.route('/user/<username>') # 带字符串的参数
- @app.route('/post/<int:post_id>')# 带int类型的参数
- @app.route('/post/<float:post_id>')# 带float类型的参数
- @app.route('/post/<path:path>')# 带其他的路径
- @app.route('/login', methods=['GET', 'POST']) # 带提交请求的方式
a.路由的源码:
1 源码:
2 def route(self, rule, **options):
3 def decorator(f):
4 endpoint = options.pop('endpoint', None)
5 self.add_url_rule(rule, endpoint, f, **options)
6 return f
7 return decorator
8
9 说明:1.当视图函数被app.route函数执行的时候,实际上视图函数被route装饰器装饰,返回的值为decorator;相当于decorator = app.route('/',methods=['GET','POST'],endpoint='n1')
10
11 2.然后再执行@decorator,将参数传进去
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b.示例代码:
1 from flask import Flask
2
3 app = Flask(__name__)
4 app.debug = True
5 app.secret_key = "asdfasdf"
6
7 """
8 1. decorator = app.route('/',methods=['GET','POST'],endpoint='n1')
9 def route(self, rule, **options):
10 # self:app对象
11 # rule= /
12 # options = {methods=['GET','POST'],endpoint='n1'}
13 def decorator(f):
14 endpoint = options.pop('endpoint', None)
15 self.add_url_rule(rule, endpoint, f, **options)
16 return f
17 return decorator
18 2. @decorator
19 decorator(index)
20 """
21 @app.route('/',methods=['GET','POST'],endpoint='n1')
22 def index():
23 return 'Hello World!'
24
25
26 def login():
27 return '登录'
28
29 app.add_url_rule('/login', 'n2', login, methods=['GET',"POST"])
30
31
32 if __name__ == '__main__':
33 app.run()
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c.注册路由的基本原理与路由用到的参数
1 1.基于CBV的路由:
2 def auth(func):
3 def inner(*args, **kwargs):
4 print('before')
5 result = func(*args, **kwargs)
6 print('after')
7 return result
8
9 return inner
10
11 class IndexView(views.View):
12 methods = ['GET']
13 decorators = [auth, ]
14
15 def dispatch_request(self):
16 print('Index')
17 return 'Index!'
18
19 app.add_url_rule('/index', view_func=IndexView.as_view(name='index')) # name=endpoint
20
21 2.路由的基本参数:
22 @app.route和app.add_url_rule参数:
23 rule, URL规则
24 view_func, 视图函数名称
25 defaults=None, 默认值,当URL中无参数,函数需要参数时,使用defaults={'k':'v'}为函数提供参数
26 endpoint=None, 名称,用于反向生成URL,即: url_for('名称')
27 methods=None, 允许的请求方式,如:["GET","POST"]
28
29
30 strict_slashes=None, 对URL最后的 / 符号是否严格要求,
31 如:
32 @app.route('/index',strict_slashes=False),
33 访问 http://www.xx.com/index/ 或 http://www.xx.com/index均可
34 @app.route('/index',strict_slashes=True)
35 仅访问 http://www.xx.com/index
36 redirect_to=None, 重定向到指定地址
37 如:
38 @app.route('/index/<int:nid>', redirect_to='/home/<nid>')
39 或
40 def func(adapter, nid):
41 return "/home/888"
42 @app.route('/index/<int:nid>', redirect_to=func)
43 subdomain=None, 子域名访问
44 from flask import Flask, views, url_for
45
46 app = Flask(import_name=__name__)
47 app.config['SERVER_NAME'] = 'wupeiqi.com:5000'
48
49
50 @app.route("/", subdomain="admin")
51 def static_index():
52 """Flask supports static subdomains
53 This is available at static.your-domain.tld"""
54 return "static.your-domain.tld"
55
56
57 @app.route("/dynamic", subdomain="<username>")
58 def username_index(username):
59 """Dynamic subdomains are also supported
60 Try going to user1.your-domain.tld/dynamic"""
61 return username + ".your-domain.tld"
62
63
64 if __name__ == '__main__':
65 app.run()
66
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d.CVB示例代码:
1 from flask import Flask,views
2
3 app = Flask(__name__)
4 app.debug = True
5 app.secret_key = "asdfasdf"
6
7
8 def auth(func):
9 def inner(*args, **kwargs):
10 result = func(*args, **kwargs)
11 return result
12 return inner
13
14 class IndexView(views.MethodView):
15 methods = ['GET']
16 decorators = [auth, ]
17
18 def get(self):
19 return 'Index.GET'
20
21 def post(self):
22 return 'Index.POST'
23
24 app.add_url_rule('/index', view_func=IndexView.as_view(name='index')) # name=endpoint
25
26
27 if __name__ == '__main__':
28 app.run()
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e.路由参数中redirect_to与defaults的示例代码:
1 from flask import Flask
2
3 app = Flask(__name__)
4 app.debug = True
5 app.secret_key = "asdfasdf"
6
7
8 # @app.route('/',methods=['GET','POST'],endpoint='n1',defaults={'nid':888})
9 # def index(nid):
10 # print(nid)
11 # return 'Hello World!'
12 #
13 #
14 # def login():
15 # return '登录'
16 # app.add_url_rule('/login', 'n2', login, methods=['GET',"POST"])
17
18
19 @app.route('/index', methods=['GET', 'POST'], endpoint='n1', redirect_to="/index2")
20 def index():
21 return '公司老首页'
22
23
24 @app.route('/index2', methods=['GET', 'POST'], endpoint='n2')
25 def index2():
26 return '公司新首页'
27
28
29 if __name__ == '__main__':
30 app.run()
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f:路由参数中subdomain的示例代码:
1 from flask import Flask, views, url_for
2
3 app = Flask(import_name=__name__)
4 app.config['SERVER_NAME'] = 'chenjunkan.com:5000'
5
6
7 @app.route("/", subdomain="admin")
8 def static_index():
9 """Flask supports static subdomains
10 This is available at static.your-domain.tld"""
11 return "xxxxxx.your-domain.tld"
12
13
14 @app.route("/dynamic", subdomain="<username>")
15 def username_index(username):
16 """Dynamic subdomains are also supported
17 Try going to user1.your-domain.tld/dynamic"""
18 return username + ".your-domain.tld"
19
20
21 if __name__ == '__main__':
22 app.run()
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g:自定义正则路由匹配
1 from flask import Flask, views, url_for
2 from werkzeug.routing import BaseConverter
3
4 app = Flask(import_name=__name__)
5
6
7 class RegexConverter(BaseConverter):
8 """
9 自定义URL匹配正则表达式
10 """
11 def __init__(self, map, regex):
12 super(RegexConverter, self).__init__(map)
13 self.regex = regex
14
15 def to_python(self, value):
16 """
17 路由匹配时,匹配成功后传递给视图函数中参数的值
18 :param value:
19 :return:
20 """
21 return int(value)
22
23 def to_url(self, value):
24 """
25 使用url_for反向生成URL时,传递的参数经过该方法处理,返回的值用于生成URL中的参数
26 :param value:
27 :return:
28 """
29 val = super(RegexConverter, self).to_url(value)
30 return val
31
32 # 添加到flask中
33 app.url_map.converters['regex'] = RegexConverter
34
35
36 @app.route('/index/<regex("\d+"):nid>')
37 def index(nid):
38 print(url_for('index', nid='888'))
39 return 'Index'
40
41
42 if __name__ == '__main__':
43 app.run()
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8.模板
1、模板的使用
Flask使用的是Jinja2模板,所以其语法和Django无差别
2、自定义模板方法
Flask中自定义模板方法的方式和Bottle相似,创建一个函数并通过参数的形式传入render_template
注意:Markup等价django的mark_safe
9.请求跟响应
1 from flask import Flask
2 from flask import request
3 from flask import render_template
4 from flask import redirect
5 from flask import make_response
6
7 app = Flask(__name__)
8
9
10 @app.route('/login.html', methods=['GET', "POST"])
11 def login():
12
13 # 请求相关信息
14 # request.method
15 # request.args
16 # request.form
17 # request.values
18 # request.cookies
19 # request.headers
20 # request.path
21 # request.full_path
22 # request.script_root
23 # request.url
24 # request.base_url
25 # request.url_root
26 # request.host_url
27 # request.host
28 # request.files
29 # obj = request.files['the_file_name']
30 # obj.save('/var/www/uploads/' + secure_filename(f.filename))
31
32 # 响应相关信息
33 # return "字符串"
34 # return render_template('html模板路径',**{})
35 # return redirect('/index.html')
36
37 # response = make_response(render_template('index.html'))
38 # response是flask.wrappers.Response类型
39 # response.delete_cookie('key')
40 # response.set_cookie('key', 'value')
41 # response.headers['X-Something'] = 'A value'
42 # return response
43
44
45 return "内容"
46
47 if __name__ == '__main__':
48 app.run()
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10:session的使用
除请求对象之外,还有一个 session 对象。它允许你在不同请求间存储特定用户的信息。它是在 Cookies 的基础上实现的,并且对 Cookies 进行密钥签名要使用会话,你需要设置一个密钥。
- 设置:session['username'] = 'xxx'
- 删除:session.pop('username', None)
a.基本使用
1 from flask import Flask, session, redirect, url_for, escape, request
2
3 app = Flask(__name__)
4
5 @app.route('/')
6 def index():
7 if 'username' in session:
8 return 'Logged in as %s' % escape(session['username'])
9 return 'You are not logged in'
10
11 @app.route('/login', methods=['GET', 'POST'])
12 def login():
13 if request.method == 'POST':
14 session['username'] = request.form['username']
15 return redirect(url_for('index'))
16 return '''
17 <form action="" method="post">
18 <p><input type=text name=username>
19 <p><input type=submit value=Login>
20 </form>
21 '''
22
23 @app.route('/logout')
24 def logout():
25 # remove the username from the session if it's there
26 session.pop('username', None)
27 return redirect(url_for('index'))
28
29 # set the secret key. keep this really secret:
30 app.secret_key = 'A0Zr98j/3yX R~XHH!jmN]LWX/,?RT'
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b.自定义session,后续的请求上下文中会详细介绍Flask-Session
1 pip3 install Flask-Session
2
3 run.py
4 from flask import Flask
5 from flask import session
6 from pro_flask.utils.session import MySessionInterface
7 app = Flask(__name__)
8
9 app.secret_key = 'A0Zr98j/3yX R~XHH!jmN]LWX/,?RT'
10 app.session_interface = MySessionInterface()
11
12 @app.route('/login.html', methods=['GET', "POST"])
13 def login():
14 print(session)
15 session['user1'] = 'alex'
16 session['user2'] = 'alex'
17 del session['user2']
18
19 return "内容"
20
21 if __name__ == '__main__':
22 app.run()
23
24 session.py
25 #!/usr/bin/env python
26 # -*- coding:utf-8 -*-
27 import uuid
28 import json
29 from flask.sessions import SessionInterface
30 from flask.sessions import SessionMixin
31 from itsdangerous import Signer, BadSignature, want_bytes
32
33
34 class MySession(dict, SessionMixin):
35 def __init__(self, initial=None, sid=None):
36 self.sid = sid
37 self.initial = initial
38 super(MySession, self).__init__(initial or ())
39
40
41 def __setitem__(self, key, value):
42 super(MySession, self).__setitem__(key, value)
43
44 def __getitem__(self, item):
45 return super(MySession, self).__getitem__(item)
46
47 def __delitem__(self, key):
48 super(MySession, self).__delitem__(key)
49
50
51
52 class MySessionInterface(SessionInterface):
53 session_class = MySession
54 container = {}
55
56 def __init__(self):
57 import redis
58 self.redis = redis.Redis()
59
60 def _generate_sid(self):
61 return str(uuid.uuid4())
62
63 def _get_signer(self, app):
64 if not app.secret_key:
65 return None
66 return Signer(app.secret_key, salt='flask-session',
67 key_derivation='hmac')
68
69 def open_session(self, app, request):
70 """
71 程序刚启动时执行,需要返回一个session对象
72 """
73 sid = request.cookies.get(app.session_cookie_name)
74 if not sid:
75 sid = self._generate_sid()
76 return self.session_class(sid=sid)
77
78 signer = self._get_signer(app)
79 try:
80 sid_as_bytes = signer.unsign(sid)
81 sid = sid_as_bytes.decode()
82 except BadSignature:
83 sid = self._generate_sid()
84 return self.session_class(sid=sid)
85
86 # session保存在redis中
87 # val = self.redis.get(sid)
88 # session保存在内存中
89 val = self.container.get(sid)
90
91 if val is not None:
92 try:
93 data = json.loads(val)
94 return self.session_class(data, sid=sid)
95 except:
96 return self.session_class(sid=sid)
97 return self.session_class(sid=sid)
98
99 def save_session(self, app, session, response):
100 """
101 程序结束前执行,可以保存session中所有的值
102 如:
103 保存到resit
104 写入到用户cookie
105 """
106 domain = self.get_cookie_domain(app)
107 path = self.get_cookie_path(app)
108 httponly = self.get_cookie_httponly(app)
109 secure = self.get_cookie_secure(app)
110 expires = self.get_expiration_time(app, session)
111
112 val = json.dumps(dict(session))
113
114 # session保存在redis中
115 # self.redis.setex(name=session.sid, value=val, time=app.permanent_session_lifetime)
116 # session保存在内存中
117 self.container.setdefault(session.sid, val)
118
119 session_id = self._get_signer(app).sign(want_bytes(session.sid))
120
121 response.set_cookie(app.session_cookie_name, session_id,
122 expires=expires, httponly=httponly,
123 domain=domain, path=path, secure=secure)
View Code
c:第三方的session
1 """
2 pip3 install redis
3 pip3 install flask-session
4
5 """
6
7
8 from flask import Flask, session, redirect
9 from flask.ext.session import Session
10
11
12 app = Flask(__name__)
13 app.debug = True
14 app.secret_key = 'asdfasdfasd'
15
16
17 app.config['SESSION_TYPE'] = 'redis'
18 from redis import Redis
19 app.config['SESSION_REDIS'] = Redis(host='192.168.0.94',port='6379')
20 Session(app)
21
22
23 @app.route('/login')
24 def login():
25 session['username'] = 'alex'
26 return redirect('/index')
27
28
29 @app.route('/index')
30 def index():
31 name = session['username']
32 return name
33
34
35 if __name__ == '__main__':
36 app.run()
View Code
11:Blueprint
- 蓝图URL前缀:xxx = Blueprint('account', __name__,url_prefix='/xxx')
- 蓝图子域名:xxx = Blueprint('account', __name__,subdomain='admin')
示例代码:
12:message
message是一个基于Session实现的用于保存数据的集合,其特点是:使用一次就删除。
1 from flask import Flask, flash, redirect, render_template, request, get_flashed_messages
2
3 app = Flask(__name__)
4 app.secret_key = 'some_secret'
5
6
7 @app.route('/')
8 def index1():
9 messages = get_flashed_messages()
10 print(messages)
11 return "Index1"
12
13
14 @app.route('/set')
15 def index2():
16 v = request.args.get('p')
17 flash(v)
18 return 'ok'
19
20
21 if __name__ == "__main__":
22 app.run()
View Code
13:中间件
1 from flask import Flask, flash, redirect, render_template, request
2
3 app = Flask(__name__)
4 app.secret_key = 'some_secret'
5
6 @app.route('/')
7 def index1():
8 return render_template('index.html')
9
10 @app.route('/set')
11 def index2():
12 v = request.args.get('p')
13 flash(v)
14 return 'ok'
15
16 class MiddleWare:
17 def __init__(self,wsgi_app):
18 self.wsgi_app = wsgi_app
19
20 def __call__(self, *args, **kwargs):
21
22 return self.wsgi_app(*args, **kwargs)
23
24 if __name__ == "__main__":
25 app.wsgi_app = MiddleWare(app.wsgi_app)
26 app.run(port=9999)
View Code
14:请求扩展
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 from flask import Flask, Request, render_template
4
5 app = Flask(__name__, template_folder='templates')
6 app.debug = True
7
8
9 @app.before_first_request
10 def before_first_request1():
11 print('before_first_request1')
12
13
14 @app.before_first_request
15 def before_first_request2():
16 print('before_first_request2')
17
18
19 @app.before_request
20 def before_request1():
21 Request.nnn = 123
22 print('before_request1')
23
24
25 @app.before_request
26 def before_request2():
27 print('before_request2')
28
29
30 @app.after_request
31 def after_request1(response):
32 print('before_request1', response)
33 return response
34
35
36 @app.after_request
37 def after_request2(response):
38 print('before_request2', response)
39 return response
40
41
42 @app.errorhandler(404)
43 def page_not_found(error):
44 return 'This page does not exist', 404
45
46
47 @app.template_global()
48 def sb(a1, a2):
49 return a1 + a2
50
51
52 @app.template_filter()
53 def db(a1, a2, a3):
54 return a1 + a2 + a3
55
56
57 @app.route('/')
58 def hello_world():
59 return render_template('hello.html')
60
61
62 if __name__ == '__main__':
63 app.run()
View Code
15:flask插件
http://flask.pocoo.org/extensions/