Flask(二)

一.threading.local

多个线程修改同一个数据,复制多份变量给每个线程用,为每个线程开辟一块空间进行数据存储

不用threading.local (多线程资源共享,sleep后执行取到的都是最后一次修改的值)

# 不用local
from threading import Thread
import time
cxw = -1
def task(arg):
    global cxw
    cxw = arg
    # time.sleep(2)
    print(cxw)
​
for i in range(10):
    t = Thread(target=task,args=(i,))
    t.start()

###threading.local使用 (给每一个线程都指定了一个id存储各自修改的属性值,彼此数据隔离)

from threading import Thread
from threading import local
import time
from threading import get_ident
# 特殊的对象
cxw = local()
def task(arg):
    # 对象.val = 1/2/3/4/5
    cxw.value = arg
    time.sleep(2)
    print(cxw.value)
for i in range(10):
    t = Thread(target=task,args=(i,))
    t.start()

通过字典自定义threading.local(函数)

from threading import get_ident,Thread
import time
storage = {}
def set(k,v):
    ident = get_ident()
    if ident in storage:
        storage[ident][k] = v
    else:
        storage[ident] = {k:v}
def get(k):
    ident = get_ident()
    return storage[ident][k]
def task(arg):
    set('val',arg)
    v = get('val')
    print(v)
​
for i in range(10):
    t = Thread(target=task,args=(i,))
    t.start()

 

面向对象版

from threading import get_ident,Thread
import time
class Local(object):
    storage = {}
    def set(self, k, v):
        ident = get_ident()
        if ident in Local.storage:
            Local.storage[ident][k] = v
        else:
            Local.storage[ident] = {k: v}
    def get(self, k):
        ident = get_ident()
        return Local.storage[ident][k]
obj = Local()
def task(arg):
    obj.set('val',arg) 
    v = obj.get('val')
    print(v)
for i in range(10):
    t = Thread(target=task,args=(i,))
    t.start()

 

通过setattr和getattr实现

from threading import get_ident,Thread
import time
class Local(object):
    storage = {}
    def __setattr__(self, k, v):
        ident = get_ident()
        if ident in Local.storage:
            Local.storage[ident][k] = v
        else:
            Local.storage[ident] = {k: v}
    def __getattr__(self, k):
        ident = get_ident()
        return Local.storage[ident][k]
obj = Local()
def task(arg):
    obj.val = arg
    print(obj.val)
for i in range(10):
    t = Thread(target=task,args=(i,))
    t.start()

 

每个对象有自己的存储空间(字典)

from threading import get_ident,Thread
import time
class Local(object):
    def __init__(self):
        object.__setattr__(self,'storage',{})
        self.storage={}
    def __setattr__(self, k, v):
        ident = get_ident()
        if ident in self.storage:
            self.storage[ident][k] = v
        else:
            self.storage[ident] = {k: v}
    def __getattr__(self, k):
        ident = get_ident()
        return self.storage[ident][k]
obj = Local()
def task(arg):
    obj.val = arg
    obj.xxx = arg
    print(obj.val)
for i in range(10):
    t = Thread(target=task,args=(i,))
    t.start()

 

兼容线程和协程(源码到request中去看,看local的getattr,setattr)

try:
    from greenlet import getcurrent as get_ident
except Exception as e:
    from threading import get_ident
from threading import Thread
import time
class Local(object):
    def __init__(self):
        object.__setattr__(self,'storage',{})
    def __setattr__(self, k, v):
        ident = get_ident()
        if ident in self.storage:
            self.storage[ident][k] = v
        else:
            self.storage[ident] = {k: v}
    def __getattr__(self, k):
        ident = get_ident()
        return self.storage[ident][k]
obj = Local()
def task(arg):
    obj.val = arg
    obj.xxx = arg
    print(obj.val)
for i in range(10):
    t = Thread(target=task,args=(i,))
    t.start()   

partial偏函数

#偏函数的第二个部分(可变参数),按原有函数的参数顺序进行补充,参数将作用在原函数上,最后偏函数返回一个新函数
from functools import partial
def test(a,b,c,d):
    return a+b+c+d
​
tes=partial(test,1,2)
print(tes(3,4))

二.请求上下文

'''
全局的变量
_request_ctx_stack = LocalStack()
_app_ctx_stack = LocalStack()
current_app = LocalProxy(_find_app)
#local就是我们的partial(_lookup_req_object, "request")
request = LocalProxy(partial(_lookup_req_object, "request"))
session = LocalProxy(partial(_lookup_req_object, "session"))
g = LocalProxy(partial(_lookup_app_object, "g"))

self.wsgi_app(environ, start_response)源码:
    def wsgi_app(self, environ, start_response):
        #ctx是ResquestContext的对象,里面request
        ctx = self.request_context(environ)
        error = None
        try:
            try:
                #就是ctx放到了Local对象
                ctx.push()
                #所有请求的执行函数的,包括请求扩展,真正的视图函数
                response = self.full_dispatch_request()
            except Exception as e:
                error = e
                response = self.handle_exception(e)
            except:  # noqa: B001
                error = sys.exc_info()[1]
                raise
            # 请求之后的函数
            return response(environ, start_response)
        finally:
            if self.should_ignore_error(error):
                error = None
            ctx.auto_pop(error)
1 ctx = self.request_context(environ) environ,请求相关的,ctx现在是包含request,session的RequestContext的对象
    源码:
        1.1RequestContext(self, environ) self ,是app对象 environ,请求相关的
        1.2 RequestContext在实例化的时候的源码:
        def __init__(self, app, environ, request=None, session=None):
            self.app = app
            if request is None:
                request = app.request_class(environ)
            self.request = request
            self.url_adapter = None
            try:
                self.url_adapter = app.create_url_adapter(self.request)
            except HTTPException as e:
                self.request.routing_exception = e
            self.flashes = None
            self.session = session
            self._implicit_app_ctx_stack = []
            self.preserved = False
            self._after_request_functions = []
        这个RequestContext对象封装了,request 和seesoin

2  ctx.push()这个ctx是RequestContext,那就执行RequestContext.push方法
    2.1RequestContext.push()的源码
        def push(self):
            #_request_ctx_stack是localStack的对象
            #self是ctx,把self也就ctx放入到local对象里面
            _request_ctx_stack.push(self)
            if self.session is None:
                session_interface = self.app.session_interface
                self.session = session_interface.open_session(self.app, self.request)

                if self.session is None:
                    self.session = session_interface.make_null_session(self.app)

            if self.url_adapter is not None:
                self.match_request()
        2.1.1 _request_ctx_stack.push(self)现在的self是ctx
        2.1.2 _request_ctx_stack是LocalStack()的对象
        2.1.3 LocalStack()的push把ctx传过来
        2.1.4 LocalStack()的push方法
            源码:
            #obj是ctx
            def push(self, obj):
                #obj是ctx,requestContext的对象
                rv = getattr(self._local, "stack", None)
                if rv is None:
                    # self._local是Local()的对象
                    # storage[“线程id或者协程id”][stack] = [ctx,]
                    self._local.stack = rv = []
                rv.append(obj)
                return rv

    2的最终也就是ctx.push()他的最终目的:把当前的ctx放入到Local()里面

3  response = self.full_dispatch_request()
    源码:
        def full_dispatch_request(self):
            #这是服务器第一次请求时候执行的函数
            self.try_trigger_before_first_request_functions()
            try:
                request_started.send(self)
                #执行请求之前所有的函数,并且拿到请求之前的返回值
                rv = self.preprocess_request()
                if rv is None:
                    #这个是真正视图函数,如果我的请求之前函数没有返回值才会执行
                    rv = self.dispatch_request()
            except Exception as e:
                rv = self.handle_user_exception(e)
            return self.finalize_request(rv)
    3.1 return self.finalize_request(rv)的源码:
        def finalize_request(self, rv, from_error_handler=False):
            response = self.make_response(rv)
            try:
                #请求之后的函数,after_request
                response = self.process_response(response)
                request_finished.send(self, response=response)
            except Exception:
                if not from_error_handler:
                    raise
                self.logger.exception(
                    "Request finalizing failed with an error while handling an error"
                )
            return response
4 我们的现在已经在2步的时候把我们request已经方法Locald对象中了,我们第三步的任意一个地方
都能使用我们的request,session,那他是怎么获取的?
    4.1 我们在flask导入request,这个request是一个全局的变量,我们怎么通过request区分我当前的request对象(environ)
     我们发现request是LocalProxy的对象
    4.2 当我们用全局的request.属性的时候,就会去找LocalProxy的对象,但是我们发现里面根本就没有
        那他一定执行LocalProxy对象的__getattr__方法
    4.3 我们现在来看LocalProxy对象的__getattr__方法的源码:
        #name我们要获取属性名
        def __getattr__(self, name):
            if name == "__members__":
                return dir(self._get_current_object())
            #form
            #self._get_current_object()就是ctx里面的request,
            return getattr(self._get_current_object(), name)
        4.3.1 通过反射self._get_current_object()对象,来找我们属性,也就是name
           self._get_current_object()的源码:
                def _get_current_object(self):
                    if not hasattr(self.__local, "__release_local__"):
                        return self.__local()
                    try:
                        #self.__local就实例化传过来的偏函数,
                        return getattr(self.__local, self.__name__)
                    except AttributeError:
                        raise RuntimeError("no object bound to %s" % self.__name__)

           4.3.1.1 return getattr(self.__local, self.__name__)那这里self.__local是谁?
                    def __init__(self, local, name=None):
                          object.__setattr__(self, "_LocalProxy__local", local)
                    self.___local为local
                    这个local为实例化的时候传的
                4.3.1.1.1 这个实例化的时候的操作
                   request = LocalProxy(partial(_lookup_req_object, "request"))
                   4.3.1.1的local就是 partial(_lookup_req_object, "request")的地址
                4.3.1.1.2 _lookup_req_object的源码:
                    #调用的时候 partial(_lookup_req_object, "request")
                    #现在的name就是"request"
                    def _lookup_req_object(name):
                        # top是当前线程的ctx
                        top = _request_ctx_stack.top
                        if top is None:
                            raise RuntimeError(_request_ctx_err_msg)
                        #找top里面的request
                        # ctx找request
                        return getattr(top, name)
                4.3.1.1.2 我们来看这个_request_ctx_stack.top的top方法
                        def top(self):
                            try:
                                return self._local.stack[-1]
                            except (AttributeError, IndexError):
                                return None
                        我们发现这个self._local是Local()对象,这样就把ctx拿到了

'''

 

三.蓝图

对程序进行目录结构划分

不使用蓝图,自己分文件

目录结构:

-templates
-views
-__init__.py
   -user.py
   -order.py
-app.py

app.py

from views import app
if __name__ == '__main__':
    app.run()

init.py

from flask import Flask,request
app = Flask(__name__)
#不导入这个不行
from . import account
from . import order
from . import user

user.py

from . import app
@app.route('/user')
def user():
    return 'user'

order.py

from . import app
@app.route('/order')
def order():
    return 'order'

使用蓝图之中小型系统

详见代码:pro_flask_简单应用程序目录示例.zip

目录结构:

-flask_pro
-flask_test
  -__init__.py
  -static
       -templates
       -views
      -order.py
           -user.py
    -manage.py
       

_init.py

from flask import  Flask
app=Flask(__name__)
from flask_test.views import user
from flask_test.views import order
app.register_blueprint(user.us)
app.register_blueprint(order.ord)

manage.py

from flask_test import  app
if __name__ == '__main__':
    app.run(port=8008)

user.py

from flask import Blueprint
us=Blueprint('user',__name__)
​
@us.route('/login')
def login():
    return 'login'

order.py

from flask import Blueprint
ord=Blueprint('order',__name__)
​
@ord.route('/test')
def test():
    return 'order test'

使用蓝图之大型系统

详见代码:pro_flask_大型应用目录示例.zip

总结:

1 xxx = Blueprint('account', __name__,url_prefix='/xxx') :蓝图URL前缀,表示url的前缀,在该蓝图下所有url都加前缀

2 xxx = Blueprint('account', name,url_prefix='/xxx',template_folder='tpls'):给当前蓝图单独使用templates,向上查找,当前找不到,会找总templates

3 蓝图的befort_request,对当前蓝图有效

4 大型项目,可以模拟出类似于django中app的概念

四.g对象

from flask import Flask,views,session,request,g
app=Flask(__name__)
''''
session 只要设置,在任意请求中都能拿到,无论你拿多少次
flash   一旦设置,可在任意一次请求中获取,但是只能取一次
g     一旦设置,只能在当前请求中获取,其它的请求都不能获取


'''

@app.after_request
def test(response):
    print(g.name)
    return response



@app.route("/")
def index():
    g.name = "suv"
    return "ok"

@app.route("/index")
def index1():

    return "ojbk"



if __name__ == '__main__':

    app.run()

五.flask-session

作用:将默认保存的签名cookie中的值 保存到 redis/memcached/file/Mongodb/SQLAlchemy

安装:pip3 install flask-session

 

from flask import Flask,session
from flask_session import RedisSessionInterface
import redis
app = Flask(__name__)
conn=redis.Redis(host='127.0.0.1',port=6379)

#use_signer是否对key签名
#如果use_siginer为False,这表示不需要配置app.secret_key
#permanent=False表示关闭浏览器cookie失效
app.secret_key="aksdhkajs" app.session_interface=RedisSessionInterface(conn,key_prefix='lqz', use_signer=True,permanent=False) ''' 之前的session seesion名字为配置文件中的名字 存 seesion ->加密-->cookie 取 session -->值 ----》解密 redis的seesion: seesion名字为配置文件中的名字(默认为session)

前台cookie => session:session.id

redis => name:value name=self.key_prefix + session.sid, value=val 是redis的值
''' @app.route('/') def hello_world(): session['name']='lqz' return 'Hello World!' @app.route("/index") def index(): print(session['name']) return "ok" if __name__ == '__main__': app.run()

第二种简便方式:

from flask import Flask,session
from redis import Redis
from flask_session import Session
app = Flask(__name__)
app.config['SESSION_TYPE'] = 'redis'
app.config['SESSION_REDIS'] = Redis(host='127.0.0.1',port='6379')
Session(app)

@app.route('/')
def hello_world():
    session['name']='lqz'
    return 'Hello World!'

@app.route("/index")
def index():
    print(session['name'])
    return "ok"


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

 

六.信号

Flask框架中的信号基于blinker,其主要就是让开发者可是在flask请求过程中定制一些用户行为

安装:pip3 install blinker

内置信号:

```python
request_started = _signals.signal('request-started')                # 请求到来前执行
request_finished = _signals.signal('request-finished')              # 请求结束后执行
 
before_render_template = _signals.signal('before-render-template')  # 模板渲染前执行
template_rendered = _signals.signal('template-rendered')            # 模板渲染后执行
 
got_request_exception = _signals.signal('got-request-exception')    # 请求执行出现异常时执行
 
request_tearing_down = _signals.signal('request-tearing-down')      # 请求执行完毕后自动执行(无论成功与否)
appcontext_tearing_down = _signals.signal('appcontext-tearing-down')# 应用上下文执行完毕后自动执行(无论成功与否)
 
appcontext_pushed = _signals.signal('appcontext-pushed')            # 应用上下文push时执行
appcontext_popped = _signals.signal('appcontext-popped')            # 应用上下文pop时执行
message_flashed = _signals.signal('message-flashed')                # 调用flask在其中添加数据时,自动触发
```


使用信号:

from flask import Flask,signals,render_template

app = Flask(__name__)

# 往信号中注册函数
def func12123(*args,**kwargs):
    print('触发型号',args,kwargs)
signals.request_started.connect(func12123)

# 触发信号: signals.request_started.send()
@app.before_first_request
def before_first1(*args,**kwargs):
    pass
@app.before_first_request
def before_first2(*args,**kwargs):
    pass

@app.before_request
def before_first3(*args,**kwargs):
    pass

@app.route('/',methods=['GET',"POST"])
def index():
    print('视图')
    return "ok"


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

自定义信号:

from flask import Flask, current_app, flash, render_template
from flask.signals import _signals

app = Flask(import_name=__name__)

# 自定义信号
xxxxx = _signals.signal('xxxxx')


# 必须有一个位置参数,去接收他的发送者,
def func(sender,name):
    print(sender)
    print(name)
    print("123")



# 自定义信号中注册函数
xxxxx.connect(func)


@app.route("/x")
def index():
    # 触发信号,这里的第一是发送者,第二个参数可选的话,必须是键值对
    xxxxx.send("sb",name="wb")
    return 'Index'


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

 

 

 

posted @ 2019-10-02 13:33  纵横捭阖行  阅读(155)  评论(0编辑  收藏  举报