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。
安装Flask
pip3 install flask
Werkzeug :
from werkzeug.wrappers import Request, Response@Request.applicationdef hello(request): ???return Response(‘Hello World!‘)if __name__ == ‘__main__‘: ???from werkzeug.serving import run_simple ???run_simple(‘localhost‘, 4000, hello)
基本使用
from flask import Flaskapp = Flask(__name__) @app.route(‘/‘)def hello_world(): ???return ‘Hello World!‘ if __name__ == ‘__main__‘: ???app.run()
配置文件
flask中的配置文件是一个flask.config.Config对象（继承字典）,默认配置为： ???{ ???????‘DEBUG‘: ???????????????????????????????get_debug_flag(default=False), ?是否开启Debug模式 ???????‘TESTING‘: ?????????????????????????????False, ?????????????????????????是否开启测试模式 ???????‘PROPAGATE_EXCEPTIONS‘: ????????????????None, ?????????????????????????????????‘PRESERVE_CONTEXT_ON_EXCEPTION‘: ???????None, ???????‘SECRET_KEY‘: ??????????????????????????None, ???????‘PERMANENT_SESSION_LIFETIME‘: ??????????timedelta(days=31), ???????‘USE_X_SENDFILE‘: ??????????????????????False, ???????‘LOGGER_NAME‘: ?????????????????????????None, ???????‘LOGGER_HANDLER_POLICY‘: ??????????????‘always‘, ???????‘SERVER_NAME‘: ?????????????????????????None, ???????‘APPLICATION_ROOT‘: ????????????????????None, ???????‘SESSION_COOKIE_NAME‘: ?????????????????‘session‘, ???????‘SESSION_COOKIE_DOMAIN‘: ???????????????None, ???????‘SESSION_COOKIE_PATH‘: ?????????????????None, ???????‘SESSION_COOKIE_HTTPONLY‘: ?????????????True, ???????‘SESSION_COOKIE_SECURE‘: ???????????????False, ???????‘SESSION_REFRESH_EACH_REQUEST‘: ????????True, ???????‘MAX_CONTENT_LENGTH‘: ??????????????????None, ???????‘SEND_FILE_MAX_AGE_DEFAULT‘: ???????????timedelta(hours=12), ???????‘TRAP_BAD_REQUEST_ERRORS‘: ?????????????False, ???????‘TRAP_HTTP_EXCEPTIONS‘: ????????????????False, ???????‘EXPLAIN_TEMPLATE_LOADING‘: ????????????False, ???????‘PREFERRED_URL_SCHEME‘: ????????????????‘http‘, ???????‘JSON_AS_ASCII‘: ???????????????????????True, ???????‘JSON_SORT_KEYS‘: ??????????????????????True, ???????‘JSONIFY_PRETTYPRINT_REGULAR‘: ?????????True, ???????‘JSONIFY_MIMETYPE‘: ????????????????????‘application/json‘, ???????‘TEMPLATES_AUTO_RELOAD‘: ???????????????None, ???} 方式一： ???app.config[‘DEBUG‘] = True ????PS： 由于Config对象本质上是字典，所以还可以使用app.config.update(...) 方式二： ???app.config.from_pyfile("python文件名称") ???????如： ???????????settings.py ???????????????DEBUG = True ????????????app.config.from_pyfile("settings.py") ????app.config.from_envvar("环境变量名称") ???????环境变量的值为python文件名称名称，内部调用from_pyfile方法 ?????app.config.from_json("json文件名称") ???????JSON文件名称，必须是json格式，因为内部会执行json.loads ????app.config.from_mapping({‘DEBUG‘:True}) ???????字典格式 ????app.config.from_object("python类或类的路径") ????????app.config.from_object(‘pro_flask.settings.TestingConfig‘) ????????settings.py ????????????class Config(object): ???????????????DEBUG = False ???????????????TESTING = False ???????????????DATABASE_URI = ‘sqlite://:memory:‘ ????????????class ProductionConfig(Config): ???????????????DATABASE_URI = ‘mysql://user@localhost/foo‘ ????????????class DevelopmentConfig(Config): ???????????????DEBUG = True ????????????class TestingConfig(Config): ???????????????TESTING = True ????????PS: 从sys.path中已经存在路径开始写 ?????????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目录路由系统
- @app.route(‘/user/<username>‘)
- @app.route(‘/post/<int:post_id>‘)
- @app.route(‘/post/<float:post_id>‘)
- @app.route(‘/post/<path:path>‘)
- @app.route(‘/login‘, methods=[‘GET‘, ‘POST‘])
常用路由系统有以上五种，所有的路由系统都是基于一下对应关系来处理：
DEFAULT_CONVERTERS = { ???‘default‘: ?????????UnicodeConverter, ???‘string‘: ??????????UnicodeConverter, ???‘any‘: ?????????????AnyConverter, ???‘path‘: ????????????PathConverter, ???‘int‘: ?????????????IntegerConverter, ???‘float‘: ???????????FloatConverter, ???‘uuid‘: ????????????UUIDConverter,}a.注册路由
def auth(func): ???????????def inner(*args, **kwargs): ???????????????print(‘before‘) ???????????????result = func(*args, **kwargs) ???????????????print(‘after‘) ???????????????return result ???????return inner ???????@app.route(‘/index.html‘,methods=[‘GET‘,‘POST‘],endpoint=‘index‘) ???????@auth ???????def index(): ???????????return ‘Index‘ ???????或 ???????????????def index(): ???????????return "Index" ???????self.add_url_rule(rule=‘/index.html‘, endpoint="index", view_func=index, methods=["GET","POST"]) ???????or ???????app.add_url_rule(rule=‘/index.html‘, endpoint="index", view_func=index, methods=["GET","POST"]) ???????app.view_functions[‘index‘] = index ???????或 ???????def auth(func): ???????????def inner(*args, **kwargs): ???????????????print(‘before‘) ???????????????result = func(*args, **kwargs) ???????????????print(‘after‘) ???????????????return result ???????return inner ???????class IndexView(views.View): ???????????methods = [‘GET‘] ???????????decorators = [auth, ] ???????????def dispatch_request(self): ???????????????print(‘Index‘) ???????????????return ‘Index!‘ ???????app.add_url_rule(‘/index‘, view_func=IndexView.as_view(name=‘index‘)) ?# name=endpoint ???????或 ???????class IndexView(views.MethodView): ???????????methods = [‘GET‘] ???????????decorators = [auth, ] ???????????def get(self): ???????????????return ‘Index.GET‘ ???????????def post(self): ???????????????return ‘Index.POST‘ ???????app.add_url_rule(‘/index‘, view_func=IndexView.as_view(name=‘index‘)) ?# name=endpoint ???????@app.route和app.add_url_rule参数： ???????????rule, ??????????????????????URL规则 ???????????view_func, ?????????????????视图函数名称 ???????????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 ???????????endpoint=None, ?????????????名称，用于反向生成URL，即： url_for(‘名称‘) ???????????methods=None, ??????????????允许的请求方式，如：["GET","POST"] ???????????????????????strict_slashes=None, ???????对URL最后的 / 符号是否严格要求， ???????????????????????????????????????如： ???????????????????????????????????????????@app.route(‘/index‘,strict_slashes=False)， ???????????????????????????????????????????????访问 http://www.xx.com/index/ 或 http://www.xx.com/index均可 ???????????????????????????????????????????@app.route(‘/index‘,strict_slashes=True) ???????????????????????????????????????????????仅访问 http://www.xx.com/index ????????????redirect_to=None, ??????????重定向到指定地址 ???????????????????????????????????????如： ???????????????????????????????????????????@app.route(‘/index/<int:nid>‘, redirect_to=‘/home/<nid>‘) ???????????????????????????????????????????或 ???????????????????????????????????????????def func(adapter, nid): ???????????????????????????????????????????????return "/home/888" ???????????????????????????????????????????@app.route(‘/index/<int:nid>‘, redirect_to=func) ???????????subdomain=None, ????????????子域名访问 ???????????????????????????????????????????????from flask import Flask, views, url_for ???????????????????????????????????????????????app = Flask(import_name=__name__) ???????????????????????????????????????????????app.config[‘SERVER_NAME‘] = ‘wupeiqi.com:5000‘ ???????????????????????????????????????????????@app.route("/", subdomain="admin") ???????????????????????????????????????????????def static_index(): ???????????????????????????????????????????????????"""Flask supports static subdomains ???????????????????????????????????????????????????This is available at static.your-domain.tld""" ???????????????????????????????????????????????????return "static.your-domain.tld" ???????????????????????????????????????????????@app.route("/dynamic", subdomain="<username>") ???????????????????????????????????????????????def username_index(username): ???????????????????????????????????????????????????"""Dynamic subdomains are also supported ???????????????????????????????????????????????????Try going to user1.your-domain.tld/dynamic""" ???????????????????????????????????????????????????return username + ".your-domain.tld" ???????????????????????????????????????????????if __name__ == ‘__main__‘: ???????????????????????????????????????????????????app.run() ???????a.注册路由原理b.自定义正则路由匹配
from flask import Flask, views, url_for ???????????from werkzeug.routing import BaseConverter ???????????app = Flask(import_name=__name__) ???????????class RegexConverter(BaseConverter): ???????????????""" ???????????????自定义URL匹配正则表达式 ???????????????""" ???????????????def __init__(self, map, regex): ???????????????????super(RegexConverter, self).__init__(map) ???????????????????self.regex = regex ???????????????def to_python(self, value): ???????????????????""" ???????????????????路由匹配时，匹配成功后传递给视图函数中参数的值 ???????????????????:param value: ????????????????????:return: ????????????????????""" ???????????????????return int(value) ???????????????def to_url(self, value): ???????????????????""" ???????????????????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 ???????????????????:param value: ????????????????????:return: ????????????????????""" ???????????????????val = super(RegexConverter, self).to_url(value) ???????????????????return val ???????????# 添加到flask中 ???????????app.url_map.converters[‘regex‘] = RegexConverter ???????????@app.route(‘/index/<regex("\d+"):nid>‘) ???????????def index(nid): ???????????????print(url_for(‘index‘, nid=‘888‘)) ???????????????return ‘Index‘ ???????????if __name__ == ‘__main__‘: ???????????????app.run()b. 自定制正则路由匹配模板
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，如：
html
<!DOCTYPE html><html><head lang="en"> ???<meta charset="UTF-8"> ???<title></title></head><body> ???<h1>自定义函数</h1> ???{{ww()|safe}}</body></html>run.py
#!/usr/bin/env python# -*- coding:utf-8 -*-from flask import Flask,render_templateapp = Flask(__name__) ?def wupeiqi(): ???return ‘<h1>Wupeiqi</h1>‘ @app.route(‘/login‘, methods=[‘GET‘, ‘POST‘])def login(): ???return render_template(‘login.html‘, ww=wupeiqi) app.run()
请求和响应
复制代码 ??from flask import Flask ???from flask import request ???from flask import render_template ???from flask import redirect ???from flask import make_response ???app = Flask(__name__) ???@app.route(‘/login.html‘, methods=[‘GET‘, "POST"]) ???def login(): ???????# 请求相关信息 ???????# request.method ???????# request.args ???????# request.form ???????# request.values ???????# request.cookies ???????# request.headers ???????# request.path ???????# request.full_path ???????# request.script_root ???????# request.url ???????# request.base_url ???????# request.url_root ???????# request.host_url ???????# request.host ???????# request.files ???????# obj = request.files[‘the_file_name‘] ???????# obj.save(‘/var/www/uploads/‘ + secure_filename(f.filename)) ???????# 响应相关信息 ???????# return "字符串" ???????# return render_template(‘html模板路径‘,**{}) ???????# return redirect(‘/index.html‘) ???????# response = make_response(render_template(‘index.html‘)) ???????# response是flask.wrappers.Response类型 ???????# response.delete_cookie(‘key‘) ???????# response.set_cookie(‘key‘, ‘value‘) ???????# response.headers[‘X-Something‘] = ‘A value‘ ???????# return response ???????return "内容" ???if __name__ == ‘__main__‘: ???????app.run()Session
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)
基本使用：
from flask import Flask, session, redirect, url_for, escape, request app = Flask(__name__) @app.route(‘/‘)def index(): ???if ‘username‘ in session: ???????return ‘Logged in as %s‘ % escape(session[‘username‘]) ???return ‘You are not logged in‘ @app.route(‘/login‘, methods=[‘GET‘, ‘POST‘])def login(): ???if request.method == ‘POST‘: ???????session[‘username‘] = request.form[‘username‘] ???????return redirect(url_for(‘index‘)) ???return ‘‘‘ ???????<form action="" method="post"> ???????????<p><input type=text name=username> ???????????<p><input type=submit value=Login> ???????</form> ???‘‘‘ @app.route(‘/logout‘)def logout(): ???# remove the username from the session if it‘s there ???session.pop(‘username‘, None) ???return redirect(url_for(‘index‘)) # set the secret key. ?keep this really secret:app.secret_key = ‘A0Zr98j/3yX R~XHH!jmN]LWX/,?RT‘
自定义session
pip3 install Flask-Session ???????????????run.py ???????????from flask import Flask ???????????from flask import session ???????????from pro_flask.utils.session import MySessionInterface ???????????app = Flask(__name__) ???????????app.secret_key = ‘A0Zr98j/3yX R~XHH!jmN]LWX/,?RT‘ ???????????app.session_interface = MySessionInterface() ???????????@app.route(‘/login.html‘, methods=[‘GET‘, "POST"]) ???????????def login(): ???????????????print(session) ???????????????session[‘user1‘] = ‘alex‘ ???????????????session[‘user2‘] = ‘alex‘ ???????????????del session[‘user2‘] ???????????????return "内容" ???????????if __name__ == ‘__main__‘: ???????????????app.run() ???????session.py ???????????#!/usr/bin/env python ???????????# -*- coding:utf-8 -*- ???????????import uuid ???????????import json ???????????from flask.sessions import SessionInterface ???????????from flask.sessions import SessionMixin ???????????from itsdangerous import Signer, BadSignature, want_bytes ???????????class MySession(dict, SessionMixin): ???????????????def __init__(self, initial=None, sid=None): ???????????????????self.sid = sid ???????????????????self.initial = initial ???????????????????super(MySession, self).__init__(initial or ()) ???????????????def __setitem__(self, key, value): ???????????????????super(MySession, self).__setitem__(key, value) ???????????????def __getitem__(self, item): ???????????????????return super(MySession, self).__getitem__(item) ???????????????def __delitem__(self, key): ???????????????????super(MySession, self).__delitem__(key) ???????????class MySessionInterface(SessionInterface): ???????????????session_class = MySession ???????????????container = {} ???????????????def __init__(self): ???????????????????import redis ???????????????????self.redis = redis.Redis() ???????????????def _generate_sid(self): ???????????????????return str(uuid.uuid4()) ???????????????def _get_signer(self, app): ???????????????????if not app.secret_key: ???????????????????????return None ???????????????????return Signer(app.secret_key, salt=‘flask-session‘, ?????????????????????????????????key_derivation=‘hmac‘) ???????????????def open_session(self, app, request): ???????????????????""" ???????????????????程序刚启动时执行，需要返回一个session对象 ???????????????????""" ???????????????????sid = request.cookies.get(app.session_cookie_name) ???????????????????if not sid: ???????????????????????sid = self._generate_sid() ???????????????????????return self.session_class(sid=sid) ???????????????????signer = self._get_signer(app) ???????????????????try: ???????????????????????sid_as_bytes = signer.unsign(sid) ???????????????????????sid = sid_as_bytes.decode() ???????????????????except BadSignature: ???????????????????????sid = self._generate_sid() ???????????????????????return self.session_class(sid=sid) ???????????????????# session保存在redis中 ???????????????????# val = self.redis.get(sid) ???????????????????# session保存在内存中 ???????????????????val = self.container.get(sid) ???????????????????if val is not None: ???????????????????????try: ???????????????????????????data = json.loads(val) ???????????????????????????return self.session_class(data, sid=sid) ???????????????????????except: ???????????????????????????return self.session_class(sid=sid) ???????????????????return self.session_class(sid=sid) ???????????????def save_session(self, app, session, response): ???????????????????""" ???????????????????程序结束前执行，可以保存session中所有的值 ???????????????????如： ???????????????????????保存到resit ???????????????????????写入到用户cookie ???????????????????""" ???????????????????domain = self.get_cookie_domain(app) ???????????????????path = self.get_cookie_path(app) ???????????????????httponly = self.get_cookie_httponly(app) ???????????????????secure = self.get_cookie_secure(app) ???????????????????expires = self.get_expiration_time(app, session) ???????????????????val = json.dumps(dict(session)) ???????????????????# session保存在redis中 ???????????????????# self.redis.setex(name=session.sid, value=val, time=app.permanent_session_lifetime) ???????????????????# session保存在内存中 ???????????????????self.container.setdefault(session.sid, val) ???????????????????session_id = self._get_signer(app).sign(want_bytes(session.sid)) ???????????????????response.set_cookie(app.session_cookie_name, session_id, ???????????????????????????????????????expires=expires, httponly=httponly, ???????????????????????????????????????domain=domain, path=path, secure=secure)自定义Sessionmessage
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。
from flask import Flask, flash, redirect, render_template, request, get_flashed_messages ???????app = Flask(__name__) ???????app.secret_key = ‘some_secret‘ ???????@app.route(‘/‘) ???????def index1(): ???????????messages = get_flashed_messages() ???????????print(messages) ???????????return "Index1" ???????@app.route(‘/set‘) ???????def index2(): ???????????v = request.args.get(‘p‘) ???????????flash(v) ???????????return ‘ok‘ ???????if __name__ == "__main__": ???????????app.run()
中间件
from flask import Flask, flash, redirect, render_template, request app = Flask(__name__)app.secret_key = ‘some_secret‘ @app.route(‘/‘)def index1(): ???return render_template(‘index.html‘) @app.route(‘/set‘)def index2(): ???v = request.args.get(‘p‘) ???flash(v) ???return ‘ok‘ class MiddleWare: ???def __init__(self,wsgi_app): ???????self.wsgi_app = wsgi_app ????def __call__(self, *args, **kwargs): ????????return self.wsgi_app(*args, **kwargs) if __name__ == "__main__": ???app.wsgi_app = MiddleWare(app.wsgi_app) ???app.run(port=9999)
web框架之Flask
原文地址：http://www.cnblogs.com/Crazy-lyl/p/7758139.html