“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。
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_simple run_simple(\'localhost\', 4000, hello)
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()
二、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
三、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, }
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()
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()
四、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:
<!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>
#!/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()
五、请求和响应
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()
六、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)
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\'
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)
七、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、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。
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()
九、中间件
from flask import Flask, flash, redirect, render_template, request app = Flask(__name__) app.secret_key = \'Flask 编写http接口api及接口自动化测试