flask

一、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，

短小精悍，可快速搭建一个小项目，而大项目就需要借助各种第三方组件来进行搭建

安装：打开cmd，输入pip3  install  flask命令

wsgi:

• werkzeug示例

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)

• wsgiref示例

from wsgiref.simple_server import make_server
                 
                def runserver(environ, start_response):
                    start_response('200 OK', [('Content-Type', 'text/html')])
                    return [bytes('<h1>Hello, web!</h1>', encoding='utf-8'), ]
                 
                 
                if __name__ == '__main__':
                    # obj = WSGIHandler()
                    httpd = make_server('', 8000, runserver)
                    httpd.serve_forever()

• 本质

import socket
                  
                def handle_request(client):
                    buf = client.recv(1024)
                    client.send("HTTP/1.1 200 OK\r\n\r\n")
                    client.send("Hello, Seven")
                  
                def main():
                    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
                    sock.bind(('localhost',8000))
                    sock.listen(5)
                  
                    while True:
                        connection, address = sock.accept()
                        handle_request(connection)
                        connection.close()
                  
                if __name__ == '__main__':
                    main()

flask简单使用

from  flask import Flask
# 实例化Flask对象
app = Flask(__name__)


#将'/'和函数index的对应关系添加到路由中
"""
{
'/':index
}
"""
@app.route('/')     #---->1.v=app.route('/')   2.v(hello_world)
def hello_world():
    return 'Hello World!'


if __name__ == '__main__':
    # 监听用户请求
    # 如果有用户请求到来，则执行app的__call__方法
    # app.__call__
    app.run()

二、flask实现登录认证

 自定义装饰器实现：

from  flask import Flask,render_template,request,redirect,session,url_for
# 实例化Flask对象
app = Flask(__name__)
app.debug=True
app.secret_key='dffffffffgre'
USER_DICT={
   1:{ 'name':'aa','age':18,'txt':'.....................................'},
   2:{ 'name':'bb','age':18,'txt':'.....................................'},
    3:{'name':'cc','age':18,'txt':'.....................................'}

}

def wrapper(func):
    def inner(*args,**kwargs):
        user = session.get('user_info')
        if not user:
            url = url_for('login')
            return redirect(url)

        return func(*args,**kwargs)

    return inner


@app.route('/detail/<int:nid>',methods=['GET','POST'],endpoint='detail')
@wrapper
def detail(nid):
    # user = session.get('user_info')
    # if not user:
    #     url = url_for('login')
    #     return redirect(url)

    info=USER_DICT[nid]
    return render_template('detail.html',info=info)

@app.route('/index',methods=['GET','POST'],endpoint='index')
@wrapper
def index():
    # user=session.get('user_info')
    # if not user:
    #     url=url_for('login')
    #     return redirect(url)

    return render_template('index.html',user_dict=USER_DICT)


@app.route('/login',methods=['GET','POST'],endpoint='login')
def login():
    if request.method=='GET':
        return render_template('login.html')
    else:
        user=request.form.get('user')
        pwd=request.form.get('pwd')
        print(user,pwd)
        if user=='aa' and pwd=='123':
            session['user_info']=user
            url=url_for('index')
            return redirect(url)
        return render_template('login.html',error='用户名或密码错误')


if __name__ == '__main__':
    # 监听用户请求
    # 如果有用户请求到来，则执行app的__call__方法
    # app.__call__
    app.run()

 使用flask的请求扩展实现：

 

from  flask import Flask,render_template,request,redirect,session,url_for
# 实例化Flask对象
app = Flask(__name__)
app.debug=True
app.secret_key='dffffffffgre'
USER_DICT={
   1:{ 'name':'aa','age':18,'txt':'.....................................'},
   2:{ 'name':'bb','age':18,'txt':'.....................................'},
    3:{'name':'cc','age':18,'txt':'.....................................'}

}
@app.before_request
def process_request():
    if request.path=='/login':
        return None

    user = session.get('user_info')
    print(user)
    if not user:
        url = url_for('n1')
        return redirect(url)
    else:
        return None



@app.route('/detail/<int:nid>',methods=['GET','POST'],endpoint='n3')
def detail(nid):
    # user = session.get('user_info')
    # if not user:
    #     url = url_for('login')
    #     return redirect(url)

    info=USER_DICT[nid]
    return render_template('detail.html',info=info)

@app.route('/index',methods=['GET','POST'],endpoint='n2')
def index():
    # user=session.get('user_info')
    # if not user:
    #     url=url_for('login')
    #     return redirect(url)

    return render_template('index.html',user_dict=USER_DICT)


@app.route('/login',methods=['GET','POST'],endpoint='n1')
def login():
    if request.method=='GET':
        return render_template('login.html')
    else:
        user=request.form.get('user')
        pwd=request.form.get('pwd')
        print(user,pwd)
        if user=='aa' and pwd=='123':
            session['user_info']=user
            url=url_for('n2')
            return redirect(url)
        return render_template('login.html',error='用户名或密码错误')


if __name__ == '__main__':
    # 监听用户请求
    # 如果有用户请求到来，则执行app的__call__方法
    # app.__call__
    app.run()

 

login.html
<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">
    <title>Title</title>
</head>

<form method="post">
<input type="text" name="user">
<input type="password" name="pwd">  <span style="color: red">{{ error }}</span>
<input type="submit" value="login">
</form>
</body>
</html>

index.html
<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">
    <title>Title</title>
</head>
<body>
<table>
    {% for key,value in user_dict.items() %}
    <tr>
        <td>{{ key }}</td>
        <td>{{ value.name }}</td>
        <td>{{ value['name']}}</td>
        <td>{{ value.get('name') }}</td>
       <td><a href="/detail/{{ key }}">查看详细</a></td>

    </tr>
    {% endfor %}

</table>


</body>
</html>

detail.html
<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">
    <title>Title</title>
</head>
<body>

<h2>详细信息{{info.name}}</h2>
<h4>{{ info.txt }}</h4>

</body>
</html>

三、flask的配置文件

flask中的配置文件是一个flask.config.Config对象（继承字典）

方式一：

　　app.config[DEBUG]=True

　　由于Config对象本质上是字典，可以使用app.config.update(...)

方式二：

　　app.config.form_pyfile("python文件名称"）

方式三：

　　app.config.form_envvar('环境变量名称')

　　环境变量的值为python文件名称，内部调用form_pyfile方法

方式四：

　　app.config.form_json("json文件名称")

　　json文件必须是json格式，内部会执行json.loads

方式五：

　　app.config.from_mapping({'DEBUG':True})

　　字典格式

方式六(最常用)：

　　app.config.from_object('python类或类的路径')   #默认从根目录开始

　　在flask程序中写入：

　 app.config.from_object('settings.DevelopmentConfig') #在settings中导入适合的配置类
　　

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

 

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,
    }

四、flask的路由系统

@app.route('/',methods=['GET','POST'],endpoint='n1')
def index():
    return 'Hello World!'


实际执行顺序为：

1.
 decorator = app.route('/',methods=['GET','POST'],endpoint='n1')
    def route(self, rule, **options):
        # app对象
        # rule= /
        # options = {methods=['GET','POST'],endpoint='n1'}
        def decorator(f):
            endpoint = options.pop('endpoint', None)
            self.add_url_rule(rule, endpoint, f, **options)
            return f
        return decorator
2. @decorator
    decorator(index)



其实也就是执行了app.add_url_rule('/login', 'n2', login, methods=['GET',"POST"])这句代码，这就跟django框架一样了

常用路由
@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'])

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,
}

 @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，

flask中的CBV
from  flask import Flask,views
# 实例化Flask对象
app = Flask(__name__)
app.config.from_object('settings.DevelopmentConfig')
# CBV

def auth(func):
    def inner(*args,**kwargs):
        result=func(*args,**kwargs)
        return result
    return inner

class IndexView(views.MethodView):
    methods = ['GET','POST']
    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就是别名

if __name__ == '__main__':
    # 监听用户请求
    # 如果有用户请求到来，则执行app的__call__方法
    # app.__call__
    app.run()

路由应用

from  flask import Flask
# 实例化Flask对象
app = Flask(__name__)

# redirect_to='/index2'参数就可使访问一个老api时跳到新api
@app.route('/index',methods=['GET','POST'],endpoint='n1',redirect_to='/index2')     
def index():
    return '老首页'
@app.route('/index2',methods=['GET','POST'],endpoint='n2')     
def index():
    return '新首页'

if __name__ == '__main__':
    # 监听用户请求
    # 如果有用户请求到来，则执行app的__call__方法
    # app.__call__
    app.run()

 

路由的子域名

from flask import Flask, views, url_for

app = Flask(import_name=__name__)
app.config['SERVER_NAME'] = 'oldboyedu.com:5000'   #配置必须有


@app.route("/", subdomain="admin")
def static_index():
    """Flask supports static subdomains
    This is available at static.your-domain.tld"""
    return "xxxxxx.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()

在本地C:\Windows\System32\drivers\etc此路径中找到hosts,更改如下

 

自定义url匹配正则表达式

from flask import Flask, views, url_for
from werkzeug.routing import BaseConverter

app = Flask(import_name=__name__)


# 1. 写RegexConverter类
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:
        """
        # "123"
        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


# 2. 将RegexConverter添加到flask中
app.url_map.converters['regex'] = RegexConverter


@app.route('/index/<regex("\d+"):nid>')
def index(nid):
    print(nid,type(nid))

    url_for('index',nid=89)
    return 'Index'


if __name__ == '__main__':
    app.run()

五、模板语法

　flask使用jinja2模板，语法和django基本无差别

　Markup和django的mark_safe相同　

 六、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

• 设置：session['user']='mmm'
• get:     user=session.get('user')
• del:     session.pop('user',None)

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)

#!/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 Session


app = 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 name


if __name__ == '__main__':
    app.run()

七、闪现（flash）

• • 基于session实现，对临时数据操作，如：显示错误信息
  • flash('')　　向某个地方设置一个值
  • get_flashed_messages()      从某个地方获取设置过的所有值，并清除

 

from flask import Flask,flash,get_flashed_messages,request,redirect

app = Flask(__name__)
app.secret_key = 'asdfasdf'      #必不可少


@app.route('/index')
def index():
    # 从某个地方获取设置过的所有值，并清除。
    val = request.args.get('v')
    if val == 'oldboy':
        return 'Hello World!'
    flash('超时错误',category="x1")
    return "ssdsdsdfsd"
    # return redirect('/error')


@app.route('/error')
def error():
    """
    展示错误信息
    :return:
    """
    data = get_flashed_messages(category_filter=['x1'])
    if data:
        msg = data[0]
    else:
        msg = "..."
    return "错误信息：%s" %(msg,)


if __name__ == '__main__':
    app.run()

 

八、请求扩展（装饰器实现）

类似于django中的中间件，其流程也与其相似，其中，process_request有返回值，则与django

以前版本相似，process_reponse必须有返回值

• @app.before_request
• @app.after_request
• @app.errorhandler                #状态码错误信息
• @app.before_first_request   #请求来只执行第一次

示例：
# 请求扩展
from flask import Flask
app = Flask(__name__)
app.debug=True

@app.before_request
def process_request1(*args,**kwargs):
    print('process_request1进来了')
@app.before_request
def process_request2(*args,**kwargs):
    print('process_request2进来了')

@app.after_request
def process_response1(response):
    print('process_response1走了')
    return response
@app.after_request
def process_response2(response):
    print('process_response2走了')
    return response

@app.before_first_request
def first(*args,**kwargs):
    print('first')

@app.errorhandler(404)
def error_404(arg):
    return "404错误了"

#可自定义模板

@app.template_global()
def sb(a1, a2):
    return a1 + a2          
#调用方式：{{sb(1,2)}}

@app.template_filter() 
def db(a1, a2, a3): 
　　return a1 + a2 + a3
#调用方式：{{ 1|db(2,3)}}

@app.route('/') 
def index():
 　　print('index函数') 
　　 return 'Hello World!' 

if __name__ == '__main__': 
　　app.run()

九、中间件

项目启动时一些额外操作

 

from flask import Flask

app = Flask(__name__)

@app.route('/')
def index():
    return 'Hello World!'

class Md(object):
    def __init__(self,old_wsgi_app):
        self.old_wsgi_app = old_wsgi_app

    def __call__(self,  environ, start_response):
        print('开始之前')
        ret = self.old_wsgi_app(environ, start_response)
        print('结束之后')
        return ret

if __name__ == '__main__':
    app.wsgi_app = Md(app.wsgi_app)
    app.run()

 

十、蓝图（blueprint）

•  自定义目录格式：示例
•  使用蓝图：

 　　　　简单程序目录格式：示例

 　　　　大型项目目录格式：示例

 自定义目录和使用蓝图的区别：

• • 使用蓝图可批量更改url，自定义不行
  • 使用蓝图方便更改模板和静态文件路径
  • 使用蓝图，可以针对app,也可以针对某个蓝图

注意：蓝图对象名称和函数名称不能重复

• 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

十一、flask插件

 http://flask.pocoo.org/extensions/