折腾：
【已解决】CentOS服务器中搭建Python的Flask的REST API
期间，给Flask中添加log，且能输出到文件中。
参考：
直接去试试：
<code>app = Flask(__name__)
log = app.logger
log.debug("app=%s", app)
api = Api(app)
log.info("api=%s", api)
</code>结果调试时没有打印出log：
flask log
Logging — Flask Documentation (0.13-dev)
Application Errors — Flask Documentation (0.12)
flask app logger not work
python – Flask logging not working at all – Stack Overflow
好像是：
默认的logger是warning之上的才打印，所以此处info和debug没有输出？
果然是的：
此处Flask的app.logger，默认的level是WARNING
-》只有warning以上的才会输出
-〉所以此处的，warning以上的error能输出，而warning和info，没有输出
-》所以为了能让debug输出的话，则去设置level即可：
<code>import logging
# from flask_pymongo import PyMongo
app = Flask(__name__)
app.logger.setLevel(logging.INFO)
log = app.logger
log.error("app=%s", app)
log.warning("app=%s", app)
log.debug("app=%s", app)
</code>结果warning和info还是没有输出
然后再去解决：
【已解决】Flask的log输出异常：file和console中无法输出指定的level的log
然后接着去：
【总结】
此处通过：
<code>from flask import Flask
from flask import jsonify
from flask_restful import Resource, Api, reqparse
import logging
from logging.handlers import RotatingFileHandler
# from flask_pymongo import PyMongo
app = Flask(__name__)
FLASK_APP = "RobotQA"
LOG_FILE_FILENAME = "logs/" + FLASK_APP + ".log"
LOG_FORMAT = "[%(asctime)s %(levelname)s %(filename)s:%(lineno)d %(funcName)s] %(message)s"
app.config['LOG_FILE_FILENAME'] = LOG_FILE_FILENAME
app.config["LOG_FORMAT"] = LOG_FORMAT
logFormatterStr = app.config["LOG_FORMAT"]
logFormatter = logging.Formatter(logFormatterStr)
fileHandler = RotatingFileHandler(
app.config['LOG_FILE_FILENAME'],
maxBytes=2*1024*1024,
backupCount=3,
encoding="UTF-8")
fileHandler.setLevel(logging.DEBUG)
fileHandler.setFormatter(logFormatter)
app.logger.addHandler(fileHandler)
streamHandler = logging.StreamHandler()
streamHandler.setFormatter(logFormatter)
streamHandler.setLevel(logging.INFO)
app.logger.addHandler(streamHandler)
app.logger.setLevel(logging.DEBUG) # set root log level
log = app.logger
log.error("error: app=%s", app)
log.warning("warning: app=%s", app)
log.info("info: app=%s", app)
log.debug("debug: app=%s", app)
api = Api(app)
log.info("api=%s", api)
...
if __name__ == "__main__":
# app.debug = True
app.run()
</code>实现了log输出：
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