Flask是一個基于Python開發并且依賴jinja2模板和Werkzeug WSGI服務的一個微型框架，對于Werkzeug本質是Socket服務端，其用于接收http請求并對請求進行預處理，然后觸發Flask框架，開發人員基于Flask框架提供的功能對請求進行相應的處理，并返回給用戶，如果要返回給用戶復雜的內容時，需要借助jinja2模板來實現對模板的處理，即：將模板和數據進行渲染，將渲染后的字符串返回給用戶瀏覽器。

“微”(micro) 并不表示你需要把整個 Web 應用塞進單個 Python 文件（雖然確實可以 ），也不意味著 Flask 在功能上有所欠缺。微框架中的“微”意味著 Flask 旨在保持核心簡單而易于擴展。Flask 不會替你做出太多決策——比如使用何種數據庫。而那些 Flask 所選擇的——比如使用何種模板引擎——則很容易替換。除此之外的一切都由可由你掌握。如此，Flask 可以與您珠聯璧合。

默認情況下，Flask 不包含數據庫抽象層、表單驗證，或是其它任何已有多種庫可以勝任的功能。然而，Flask 支持用擴展來給應用添加這些功能，如同是 Flask 本身實現的一樣。眾多的擴展提供了數據庫集成、表單驗證、上傳處理、各種各樣的開放認證技術等功能。Flask 也許是“微小”的，但它已準備好在需求繁雜的生產環境中投入使用。

pip3 install flask from werkzeug.wrappers import Request, Response@Request.application def hello(request):return Response('Hello World!')if __name__ == '__main__':from werkzeug.serving import run_simplerun_simple('localhost', 4000, hello) werkzeug

一. 基本使用

from flask import Flask app = Flask(__name__)@app.route('/') def hello_world():return 'Hello World!'if __name__ == '__main__':app.run()

flask添加裝飾器

from flask import Flask import functoolsdef auth(func):@functools.wraps(func) # 保留函數的元信息def inner(*args,**kwargs):print('before')ret = func(*args,**kwargs)print('after')return retreturn innerapp = Flask(__name__)@app.route('/index') @auth def index():print('index')return 'index'if __name__ == '__main__':app.run()

指定端口號

from werkzeug.wrappers import Request, Response from werkzeug.serving import run_simple@Request.application def hello(request):# ...# Flask框架# return Response('Hello World!')if __name__ == '__main__':run_simple('localhost', 4000, hello) # hello()

示例：before_request和after_request

from flask import Flask,render_template,request,redirect,sessionapp = Flask(__name__)app.secret_key = '39jrlasdfoajslfu8af'# [b1,b2] @app.before_request def b1():print('b1')return 'gun'@app.before_request def b2():print('b2')# [a1,a2] -> [a2,a1] @app.after_request def a1(response):print('a1')return response@app.after_request def a2(response):print('a2')return response@app.route('/index') def index():print('index')return 'index'if __name__ == '__main__':app.run()

基于裝飾器做用戶認證

from flask import Flask,render_template,request,redirect,session app = Flask(__name__) app.secret_key = '39jrlasdfoajslfu8af' import functoolsdef auth(func):@functools.wraps(func) # 保留函數的元信息 一定要記得添加這行代碼def inner(*args,**kwargs):if not session.get('user_info'):return redirect('/login')ret = func(*args,**kwargs)return retreturn inner@app.route('/login',methods=['GET','POST']) def login():if request.method == 'GET':return render_template('login.html')user = request.form.get('user')pwd = request.form.get('pwd')if user == 'xiao' and pwd == 'xiao':session['user_info'] = userreturn redirect('/index')return render_template('login.html',msg="用戶名或密碼錯誤")@app.route('/index') @auth def index():kuang_list = [{'id':1,'name':'name1','address':'昌平'},{'id':2,'name':'name2','address':'昌平'},{'id':3,'name':'name3','address':'昌平'},]return render_template('index.html',klist=kuang_list)# return render_template('index.html',**{'klist':kuang_list}) @app.route('/detail') @auth def detail():nid = request.args.get('nid')return render_template('detail.html')@app.route('/logout') def logout():del session['user_info']return redirect('/login')if __name__ == '__main__':app.run()

基于before_request實現用戶認證

from flask import Flask,render_template,request,redirect,session app = Flask(__name__) app.secret_key = '39jrlasdfoajslfu8af'@app.before_request def xxxxxxxxxxxxxx():if request.path == '/login':return Noneif not session.get('user_info'):return redirect('/login')@app.route('/login',methods=['GET','POST']) def login():print('我是login')if request.method == 'GET':return render_template('login.html')user = request.form.get('user')pwd = request.form.get('pwd')if user == 'xiao' and pwd == 'xiao':session['user_info'] = userreturn redirect('/index')return render_template('login.html',msg="用戶名或密碼錯誤")@app.route('/index') def index():print('我是index')kuang_list = [{'id':1,'name':'name1','address':'昌平'},{'id':2,'name':'name2','address':'昌平'},{'id':3,'name':'name3','address':'昌平'},]return render_template('index.html',klist=kuang_list) # 這種傳參方式，要注意# return render_template('index.html',**{'klist':kuang_list}) # 這種傳參方式，要加**打散 @app.route('/detail') def detail():nid = request.args.get('nid')return render_template('detail.html')@app.route('/logout') def logout():del session['user_info']return redirect('/login')if __name__ == '__main__':app.run()

二、配置文件

flask中的配置文件是一個flask.config.Config對象（繼承字典）,默認配置為：{'DEBUG': get_debug_flag(default=False), 是否開啟Debug模式'TESTING': False, 是否開啟測試模式'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'] = TruePS： 由于Config對象本質上是字典，所以還可以使用app.config.update(...)方式二：app.config.from_pyfile("python文件名稱")如：settings.pyDEBUG = Trueapp.config.from_pyfile("settings.py")app.config.from_envvar("環境變量名稱")環境變量的值為python文件名稱名稱，內部調用from_pyfile方法app.config.from_json("json文件名稱")JSON文件名稱，必須是json格式，因為內部會執行json.loadsapp.config.from_mapping({'DEBUG':True})字典格式app.config.from_object("python類或類的路徑") # 寫在flask啟動的py文件里面進行配置版本app.config.from_object('pro_flask.settings.TestingConfig')settings.pyclass Config(object): # 基礎版本DEBUG = FalseTESTING = FalseDATABASE_URI = 'sqlite://:memory:'class ProductionConfig(Config): # 生產環境,線下環境DATABASE_URI = 'mysql://user@localhost/foo'class DevelopmentConfig(Config): # 開發環境DEBUG = Trueclass TestingConfig(Config): # 測試環境 各個環境下連接的數據庫是不一樣的TESTING = TruePS: 從sys.path中已經存在路徑開始寫PS: settings.py文件默認路徑要放在程序root_path目錄，如果instance_relative_config為True，則就是instance_path目錄

三、路由系統

• @app.route('/user/<username>') ?# 傳字符串 ? 他們的內部都對應一個轉換器
• @app.route('/post/<int:post_id>') ? # 傳數字
• @app.route('/post/<float:post_id>') ?# 浮點數
• @app.route('/post/<path:path>') ? # 路徑，拼url
• @app.route('/login', methods=['GET', 'POST'])，method列表里面添加的允許的請求方式，如果不添加method列表，則只允許GET請求。

常用路由系統有以上五種，所有的路由系統都是基于一下對應關系來處理：

DEFAULT_CONVERTERS = {'default': UnicodeConverter,'string': UnicodeConverter,'any': AnyConverter,'path': PathConverter,'int': IntegerConverter,'float': FloatConverter,'uuid': UUIDConverter, } def auth(func):def inner(*args, **kwargs):print('before')result = func(*args, **kwargs)print('after')return resultreturn inner@app.route('/index.html',methods=['GET','POST'],endpoint='index')@authdef index():return 'Index'或def index():return "Index"self.add_url_rule(rule='/index.html', endpoint="index", view_func=index, methods=["GET","POST"])orapp.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 resultreturn innerclass 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參數：rule, URL規則view_func, 視圖函數名稱defaults=None, 默認值,當URL中無參數，函數需要參數時，使用defaults={'k':'v'}為函數提供參數endpoint=None, 名稱，用于反向生成URL，即： url_for('名稱')methods=None, 允許的請求方式，如：["GET","POST"]strict_slashes=None, 對URL最后的 / 符號是否嚴格要求，如：@app.route('/index',strict_slashes=False)，訪問 http://www.xx.com/index/ 或 http://www.xx.com/index均可@app.route('/index',strict_slashes=True)僅訪問 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, 子域名訪問from flask import Flask, views, url_forapp = Flask(import_name=__name__)app.config['SERVER_NAME'] = 'wupeiqi.com:5000'@app.route("/", subdomain="admin")def static_index():"""Flask supports static subdomainsThis 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 supportedTry going to user1.your-domain.tld/dynamic"""return username + ".your-domain.tld"if __name__ == '__main__':app.run() a.注冊路由原理 from flask import Flask, views, url_forfrom werkzeug.routing import BaseConverterapp = Flask(import_name=__name__)class RegexConverter(BaseConverter):"""自定義URL匹配正則表達式"""def __init__(self, map, regex):super(RegexConverter, self).__init__(map)self.regex = regexdef to_python(self, value):"""路由匹配時，匹配成功后傳遞給視圖函數中參數的值:param value: :return: """return int(value)def to_url(self, value):"""使用url_for反向生成URL時，傳遞的參數經過該方法處理，返回的值用于生成URL中的參數: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. 自定制正則路由匹配 app.url_map.converters['regex'] = RegexConverter # 這個寫在啟動py文件里，告訴flask我自己要定義一個路由轉換器啦，名字叫regex # 轉換器對應的類就是RegexConverterclass RegexConverter(BaseConverter):"""自定義URL匹配正則表達式"""def __init__(self, map, regex):# 參數regex接收傳過來的nid參數super(RegexConverter, self).__init__(map)self.regex = regexdef to_python(self, value):"""路由匹配時，匹配成功后傳遞給視圖函數中參數的值:param value::return:"""return int(value)def to_url(self, value):"""使用url_for反向生成URL時，傳遞的參數經過該方法處理，返回的值用于生成URL中的參數:param value::return:"""val = super(RegexConverter, self).to_url(value)return valapp.url_map.converters['xxx'] = RegexConverter@app.route('/index/<xxx("\d+"):nid>',methods=['GET','POST']) # 定義好轉換器之后，就這樣寫了。 def index(nid):print(nid,type(nid))v = url_for('index',nid=999) # /index/999print(v)return "Index"

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添加路由的兩種方式

# 路由方式一（*）： @app.route('/index',methods=['GET','POST']) def index():return "Index"# 路由方式二： def order():return 'Order'app.add_url_rule('/order',view_func=order)

反向生成url

@app.route('/index',methods=['GET','POST'],endpoint='n1') # endpoint 給路由起別名。如果不起別名，就用函數名 def index():v1 = url_for('n1')v2 = url_for('login') # url_for 反向生成urlv3 = url_for('logout')print(v1,v2,v3)return "Index"@app.route('/login',methods=['GET','POST']) def login():return "login"@app.route('/logout',methods=['GET','POST']) def logout():return "logout"

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四、模板

1、模板的使用

Flask使用的是Jinja2模板，所以其語法和Django無差別

2、自定義模板方法

Flask中自定義模板方法的方式和Bottle相似，創建一個函數并通過參數的形式傳入render_template，如：

<!DOCTYPE html> <html> <head lang="en"><meta charset="UTF-8"><title></title> </head> <body><h1>自定義函數</h1>{{ww()|safe}}</body> </html> html #!/usr/bin/env python # -*- coding:utf-8 -*- from flask import Flask,render_template app = 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() run.py <!DOCTYPE html> <html lang="en"> <head><meta charset="UTF-8"><title>Title</title> </head> <body>{% macro input(name, type='text', value='') %}<input type="{{ type }}" name="{{ name }}" value="{{ value }}">{% endmacro %}{{ input('n1') }}{% include 'tp.html' %}<h1>asdf{{ v.k1}}</h1> </body> </html> 其他

注意：Markup等價django的mark_safe

五、請求和響應

from flask import Flask from flask import request from flask import render_template from flask import redirect from flask import make_responseapp = Flask(__name__)@app.route('/login.html', methods=['GET', "POST"]) def login():# 請求相關信息# request.method 請求的方法# request.args 獲取GET請求的內容# request.args.get("id") 獲取id的值# request.args。getlist（'ids') 獲取多個值# data = request.args# data_dict = data.to_dict() 通過to_dict()方法轉化成字典# request.remote_addr 獲取ip# request.form 獲取POST請求的值，獲取form表單里面的內容# request.values 所有的請求參數# request.cookies 獲取cookies# request.headers 獲取headers信息，是個list# request.path 僅獲取端口號和參數中間的路由 /testrequest# request.full_path# request.script_root 什么都沒獲取到# request.url 獲取完整的url，帶參數 http://192.168.1.183:5000/testrequest?a&b# request.base_url 獲取除參數外的url部分 http://192.168.1.183:5000/testrequest# request.url_root 僅獲取地址和端口號 http://192.168.1.183:5000/# request.host_url# request.host# request.files 隨請求上傳的文件# obj = request.files['the_file_name']# obj.save('/var/www/uploads/' + secure_filename(f.filename))# request.data 是請求的數據# 響應相關信息# return "字符串" 實際上是調用make_response# return render_template('html模板路徑',**{}) **{'obj'：obj}形式# return render_template('html模板路徑',obj=obj)# return redirect('/index.html')# return jsonify(**{'obj'：obj}) 返回json數據 from flask import jsonify# response = make_response(render_template('index.html'))# response是flask.wrappers.Response類型# response.delete_cookie('key')# response.set_cookie('key', 'value')# response.headers['X-Something'] = 'A value'# return responsereturn "內容"if __name__ == '__main__':app.run()

六、Session

除請求對象之外，還有一個 session 對象。它允許你在不同請求間存儲特定用戶的信息。它是在 Cookies 的基礎上實現的，并且對 Cookies 進行密鑰簽名要使用會話，你需要設置一個密鑰。

• 設置：session['username'] ＝ 'xxx'

• 刪除：session.pop('username', None)

from flask import Flask, session, redirect, url_for, escape, requestapp = 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 theresession.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' 基本使用 pip3 install Flask-Sessionrun.pyfrom flask import Flaskfrom flask import sessionfrom pro_flask.utils.session import MySessionInterfaceapp = 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 "內容"if __name__ == '__main__':app.run()session.py#!/usr/bin/env python# -*- coding:utf-8 -*-import uuidimport jsonfrom flask.sessions import SessionInterfacefrom flask.sessions import SessionMixinfrom itsdangerous import Signer, BadSignature, want_bytesclass MySession(dict, SessionMixin):def __init__(self, initial=None, sid=None):self.sid = sidself.initial = initialsuper(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 = MySessioncontainer = {}def __init__(self):import redisself.redis = redis.Redis()def _generate_sid(self):return str(uuid.uuid4())def _get_signer(self, app):if not app.secret_key:return Nonereturn Signer(app.secret_key, salt='flask-session',key_derivation='hmac')def open_session(self, app, request):"""程序剛啟動時執行，需要返回一個session對象"""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保存在內存中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):"""程序結束前執行，可以保存session中所有的值如：保存到resit寫入到用戶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保存在內存中 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) 自定義Session #!/usr/bin/env python # -*- coding:utf-8 -*- """ pip3 install redis pip3 install flask-session"""from flask import Flask, session, redirect from flask.ext.session import Sessionapp = Flask(__name__) app.debug = True app.secret_key = 'asdfasdfasd'app.config['SESSION_TYPE'] = 'redis' from redis import Redis app.config['SESSION_REDIS'] = Redis(host='192.168.0.94',port='6379') Session(app)@app.route('/login') def login():session['username'] = 'alex'return redirect('/index')@app.route('/index') def index():name = session['username']return nameif __name__ == '__main__':app.run() 第三方session

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七、藍圖

藍圖用于為應用提供目錄劃分：

小型應用程序：示例

大型應用程序：示例

其他：

• 藍圖URL前綴：xxx = Blueprint('account', __name__,url_prefix='/xxx')
• 藍圖子域名：xxx = Blueprint('account', __name__,subdomain='admin')
  # 前提需要給配置SERVER_NAME： app.config['SERVER_NAME'] = 'wupeiqi.com:5000'
  # 訪問時：admin.wupeiqi.com:5000/login.html

八、message

message是一個基于Session實現的用于保存數據的集合，其特點是：使用一次就刪除。閃現

from flask import Flask, flash, redirect, render_template, request, get_flashed_messagesapp = 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() View Code

九、中間件

from flask import Flask, flash, redirect, render_template, requestapp = 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_appdef __call__(self, *args, **kwargs):return self.wsgi_app(*args, **kwargs)if __name__ == "__main__":app.wsgi_app = MiddleWare(app.wsgi_app)app.run(port=9999) View Code

十、請求擴展

#!/usr/bin/env python # -*- coding:utf-8 -*- from flask import Flask, Request, render_templateapp = Flask(__name__, template_folder='templates') app.debug = True@app.before_first_request def before_first_request1():print('before_first_request1')@app.before_first_request def before_first_request2():print('before_first_request2')@app.before_request def before_request1():Request.nnn = 123print('before_request1')@app.before_request def before_request2():print('before_request2')@app.after_request def after_request1(response):print('before_request1', response)return response@app.after_request def after_request2(response):print('before_request2', response)return response@app.errorhandler(404) def page_not_found(error):return 'This page does not exist', 404@app.template_global() def sb(a1, a2):return a1 + a2@app.template_filter() def db(a1, a2, a3):return a1 + a2 + a3@app.route('/') def hello_world():return render_template('hello.html')if __name__ == '__main__':app.run() View Code 調用方式：{{sb(1,2)}} {{ 1|db(2,3)}}

十一、Flask插件

• WTForms ? ?
• SQLAchemy
• 等... ? ?http://flask.pocoo.org/extensions/

補充：

pip install pipreqs
安裝這個模塊之后項目里會自動生成一個requirements.txt文件，里面顯示的是這個項目安裝的模塊及其版本信息。
生成依賴文件requirements.txt 命令: pipreqs ./ (./表示當前文件)
安裝依賴文件requirements.txt 命令: pip install -r requirements.txt

?

轉載于:https://www.cnblogs.com/aaronthon/p/9362895.html

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