Detailed explanation of flask framework

1、 First we import Flask class . Examples of this class will become our WSGI application .
2、 Then we create an instance of this class . The first parameter is the name of the application module or package . If you use The first mock exam （ Like this example ）, Then you should use  name , Because the name will be based on this Whether a module is used as an application or imported as a module changes （ May be ‘main’ , It could also be the name of the actual import ）. This parameter is required , such Flask To know where to Find templates, static files, etc
3、 And then we use route() Decorator to tell Flask Trigger function URL .
4、 Function names are used to generate associated URL . The function finally returns the information that needs to be displayed in the user's browser . 

rule The parameter represents the connection with the function URL binding .

options It's going to be forwarded to the foundation Rule Object's parameter list .
In the example above ,'/ ' URL And hello_world() Function binding . therefore , When opened in a browser web Server's home page , The output of the function is rendered .
Last ,Flask Class run() Method to run the application on the local development server .

All parameters are optional

host： The host name to listen on . The default is 127.0.0.1（localhost）. Set to “0.0.0.0” To make the server available externally

port ： The default value is 5000

debug： The default is false. If set to true, Provides debugging information , Can automatically reload code and display debug information

options： To forward to the bottom Werkzeug The server .