python高级之Flask框架
目录:
- Flask基本使用
- Flask配置文件
- Flask路由系统
- Flask模版
- Flask请求与响应
- Flask之Session
- Flask之蓝图
- Flask之message
- 中间件
- Flask插件
一、Flask基本使用
1、flask简介
lask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。
2、flask安装
pip3 install flask
3、flask之werkaeug
1 from werkzeug.wrappers import Request, Response 2 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)
4、flask基本使用
1 from flask import Flask 2 app = Flask(__name__) 3 4 @app.route('/') 5 def hello_world(): 6 return 'Hello World!' 7 8 if __name__ == '__main__': 9 app.run()
二、Flask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:
1 { 2 'DEBUG': get_debug_flag(default=False), 是否开启Debug模式 3 'TESTING': False, 是否开启测试模式 4 'PROPAGATE_EXCEPTIONS': None, 5 'PRESERVE_CONTEXT_ON_EXCEPTION': None, 6 'SECRET_KEY': None, 7 'PERMANENT_SESSION_LIFETIME': timedelta(days=31), 8 'USE_X_SENDFILE': False, 9 'LOGGER_NAME': None, 10 'LOGGER_HANDLER_POLICY': 'always', 11 'SERVER_NAME': None, 12 'APPLICATION_ROOT': None, 13 'SESSION_COOKIE_NAME': 'session', 14 'SESSION_COOKIE_DOMAIN': None, 15 'SESSION_COOKIE_PATH': None, 16 'SESSION_COOKIE_HTTPONLY': True, 17 'SESSION_COOKIE_SECURE': False, 18 'SESSION_REFRESH_EACH_REQUEST': True, 19 'MAX_CONTENT_LENGTH': None, 20 'SEND_FILE_MAX_AGE_DEFAULT': timedelta(hours=12), 21 'TRAP_BAD_REQUEST_ERRORS': False, 22 'TRAP_HTTP_EXCEPTIONS': False, 23 'EXPLAIN_TEMPLATE_LOADING': False, 24 'PREFERRED_URL_SCHEME': 'http', 25 'JSON_AS_ASCII': True, 26 'JSON_SORT_KEYS': True, 27 'JSONIFY_PRETTYPRINT_REGULAR': True, 28 'JSONIFY_MIMETYPE': 'application/json', 29 'TEMPLATES_AUTO_RELOAD': None, 30 }
1、调用方式
1 方式一: 2 app.config['DEBUG'] = True 3 4 PS: 由于Config对象本质上是字典,所以还可以使用app.config.update(...) 5 6 方式二: 7 app.config.from_pyfile("python文件名称") 8 如: 9 settings.py 10 DEBUG = True 11 12 app.config.from_pyfile("settings.py") 13 14 app.config.from_envvar("环境变量名称") 15 环境变量的值为python文件名称名称,内部调用from_pyfile方法 16 17 18 app.config.from_json("json文件名称") 19 JSON文件名称,必须是json格式,因为内部会执行json.loads 20 21 app.config.from_mapping({'DEBUG':True}) 22 字典格式 23 24 app.config.from_object("python类或类的路径") 25 26 app.config.from_object('pro_flask.settings.TestingConfig') 27 28 settings.py 29 30 class Config(object): 31 DEBUG = False 32 TESTING = False 33 DATABASE_URI = 'sqlite://:memory:' 34 35 class ProductionConfig(Config): 36 DATABASE_URI = 'mysql://user@localhost/foo' 37 38 class DevelopmentConfig(Config): 39 DEBUG = True 40 41 class TestingConfig(Config): 42 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
三、Flask路由系统
1、基本路由系统
- @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,
}
1 def auth(func): 2 def inner(*args, **kwargs): 3 print('before') 4 result = func(*args, **kwargs) 5 print('after') 6 return result 7 8 return inner 9 10 @app.route('/index.html',methods=['GET','POST'],endpoint='index') 11 @auth 12 def index(): 13 return 'Index' 14 15 或 16 17 def index(): 18 return "Index" 19 20 self.add_url_rule(rule='/index.html', endpoint="index", view_func=index, methods=["GET","POST"]) 21 or 22 app.add_url_rule(rule='/index.html', endpoint="index", view_func=index, methods=["GET","POST"]) 23 app.view_functions['index'] = index 24 25 26 或 27 def auth(func): 28 def inner(*args, **kwargs): 29 print('before') 30 result = func(*args, **kwargs) 31 print('after') 32 return result 33 34 return inner 35 36 class IndexView(views.View): 37 methods = ['GET'] 38 decorators = [auth, ] 39 40 def dispatch_request(self): 41 print('Index') 42 return 'Index!' 43 44 app.add_url_rule('/index', view_func=IndexView.as_view(name='index')) # name=endpoint 45 46 47 48 或 49 50 51 class IndexView(views.MethodView): 52 methods = ['GET'] 53 decorators = [auth, ] 54 55 def get(self): 56 return 'Index.GET' 57 58 def post(self): 59 return 'Index.POST' 60 61 62 app.add_url_rule('/index', view_func=IndexView.as_view(name='index')) # name=endpoint 63 64 65 66 67 @app.route和app.add_url_rule参数: 68 rule, URL规则 69 view_func, 视图函数名称 70 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 71 endpoint=None, 名称,用于反向生成URL,即: url_for('名称') 72 methods=None, 允许的请求方式,如:["GET","POST"] 73 74 75 strict_slashes=None, 对URL最后的 / 符号是否严格要求, 76 如: 77 @app.route('/index',strict_slashes=False), 78 访问 http://www.xx.com/index/ 或 http://www.xx.com/index均可 79 @app.route('/index',strict_slashes=True) 80 仅访问 http://www.xx.com/index 81 redirect_to=None, 重定向到指定地址 82 如: 83 @app.route('/index/<int:nid>', redirect_to='/home/<nid>') 84 或 85 def func(adapter, nid): 86 return "/home/888" 87 @app.route('/index/<int:nid>', redirect_to=func) 88 subdomain=None, 子域名访问 89 from flask import Flask, views, url_for 90 91 app = Flask(import_name=__name__) 92 app.config['SERVER_NAME'] = 'wupeiqi.com:5000' 93 94 95 @app.route("/", subdomain="admin") 96 def static_index(): 97 """Flask supports static subdomains 98 This is available at static.your-domain.tld""" 99 return "static.your-domain.tld" 100 101 102 @app.route("/dynamic", subdomain="<username>") 103 def username_index(username): 104 """Dynamic subdomains are also supported 105 Try going to user1.your-domain.tld/dynamic""" 106 return username + ".your-domain.tld" 107 108 109 if __name__ == '__main__': 110 app.run() 111
3、自定义路由匹配(正则匹配)
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()
四、Flask模版
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:
1 <!DOCTYPE html> 2 <html> 3 <head lang="en"> 4 <meta charset="UTF-8"> 5 <title></title> 6 </head> 7 <body> 8 <h1>自定义函数</h1> 9 {{ww()|safe}} 10 11 </body> 12 </html> 13 复制代码
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 from flask import Flask,render_template 4 app = Flask(__name__) 5 6 7 def wangshuyang(): 8 return '<h1>Wupeiqi</h1>' 9 10 @app.route('/login', methods=['GET', 'POST']) 11 def login(): 12 return render_template('login.html', ww=wangshuyang) 13 14 app.run()
五、Flask请求与响应
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()
六、Flask之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)
1、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'
2、自定义session(Flask-Session插件)
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)
七、Flask之蓝图
蓝图用于为应用提供目录划分:
小型应用程序:示例
大型应用程序:示例
其他:
- 蓝图URL前缀:xxx = Blueprint('account', __name__,url_prefix='/xxx')
- 蓝图子域名:xxx = Blueprint('account', __name__,subdomain='admin')
# 前提需要给配置SERVER_NAME: app.config['SERVER_NAME'] = 'wupeiqi.com:5000'
# 访问时:admin.wupeiqi.com:5000/login.html
八、Flask之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。(也称为闪现)
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()
九、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 # 执行前操作 22 res = self.wsgi_app(*args, **kwargs) 23 # 执行后操作 24 return res 25 26 if __name__ == "__main__": 27 app.wsgi_app = MiddleWare(app.wsgi_app) 28 app.run(port=9999)
十、Flask插件
- Flask-Session
- WTForms
- SQLAchemy
- 等...
详见:http://flask.pocoo.org/extensions/