# 在linux系统里设置环境变量

export MAIL_USERNAME=me@greyli.com

# 用的时候取环境变量

import os

from flask import Flask

app = Flask(__name__)

app.config['MAIL_USERNAME'] = os.getenv('MAIL_USERNAME', 'me@greyli.com') # os.geteve(key,default=None)  Get an environment variable, return None if it 
# doesn't exist.The optional second argument can specify an alternate default.

from flask import Flask

app = Flask(__name__)

app.config['SECRET_KEY'] = 'some secret words'

app.config['DEBUG'] = True

app.config['ITEMS_PER_PAGE'] = 10

from flask import Flask

app = Flask(__name__)

app.config.update(

    DEBUG=True,

    SECRET_KEY='some secret words',

    ITEMS_PER_PAGE=10

)

SECRET_KEY = 'some secret words'

DEBUG = True

ITEMS_PER_PAGE = 10

import config

...

app = Flask(__name__)

app.config.from_object(configure)

...

 import os

 basedir = os.path.abspath(os.path.dirname(__file__))

 class BaseConfig:  # 基本配置类

     SECRET_KEY = os.getenv('SECRET_KEY', 'some secret words')

     ITEMS_PER_PAGE = 10

 class DevelopmentConfig(BaseConfig):

     DEBUG = True

     SQLALCHEMY_DATABASE_URI = os.getenv('DEV_DATABASE_URL', 'sqlite:///' + os.path.join(basedir, 'data-dev.sqlite')

 class TestingConfig(BaseConfig):

     TESTING = True

     SQLALCHEMY_DATABASE_URI = os.getenv('TEST_DATABASE_URL', 'sqlite:///' + os.path.join(basedir, 'data-test.sqlite')

     WTF_CSRF_ENABLED = False

 config = {

     'development': DevelopmentConfig,

     'testing': TestingConfig,

     'default': DevelopmentConfig

 }

config.py

from config import config  # 导入存储配置的字典

...

app = Flask(__name__)

app.config.from_object(config['development'])  # 获取相应的配置类

...