模块级函数

logging.getLogger([name]):返回一个logger对象，如果没有指定名字将返回root logger
logging.debug()、logging.info()、logging.warning()、logging.error()、logging.critical()：设定root logger的日志级别
logging.basicConfig():用默认Formatter为日志系统建立一个StreamHandler，设置基础配置并加到root logger中

示例：logging_level_example.py

复制代码 代码如下:
import logging
import sys

LEVELS = {\’debug\’: logging.DEBUG,
          \’info\’: logging.INFO,
          \’warning\’: logging.WARNING,
          \’error\’: logging.ERROR,
          \’critical\’: logging.CRITICAL}

if len(sys.argv) > 1:
    level_name = sys.argv[1]
    level = LEVELS.get(level_name, logging.NOTSET)
    logging.basicConfig(level=level)

logging.debug(\’This is a debug message\’)
logging.info(\’This is an info message\’)
logging.warning(\’This is a warning message\’)
logging.error(\’This is an error message\’)
logging.critical(\’This is a critical error message\’)

输出：
复制代码 代码如下:
$ python logging_level_example.py debug
DEBUG:root:This is a debug message
INFO:root:This is an info message
WARNING:root:This is a warning message
ERROR:root:This is an error message
CRITICAL:root:This is a critical error message

$ python logging_level_example.py info
INFO:root:This is an info message
WARNING:root:This is a warning message
ERROR:root:This is an error message
CRITICAL:root:This is a critical error message

Loggers

Logger.setLevel(lel):指定最低的日志级别，低于lel的级别将被忽略。debug是最低的内置级别，critical为最高
Logger.addFilter(filt)、Logger.removeFilter(filt):添加或删除指定的filter
Logger.addHandler(hdlr)、Logger.removeHandler(hdlr)：增加或删除指定的handler
Logger.debug()、Logger.info()、Logger.warning()、Logger.error()、Logger.critical()：可以设置的日志级别

示例：simple_logging_module.py

复制代码 代码如下:
import logging

# create logger
logger = logging.getLogger(\”simple_example\”)
logger.setLevel(logging.DEBUG)

# create console handler and set level to debug
ch = logging.StreamHandler()
ch.setLevel(logging.DEBUG)

# create formatter
formatter = logging.Formatter(\”%(asctime)s – %(name)s – %(levelname)s – %(message)s\”)

# add formatter to ch
ch.setFormatter(formatter)

# add ch to logger
logger.addHandler(ch)

# \”application\” code
logger.debug(\”debug message\”)
logger.info(\”info message\”)
logger.warn(\”warn message\”)
logger.error(\”error message\”)
logger.critical(\”critical message\”)

输出：
复制代码 代码如下:
$ python simple_logging_module.py
2005-03-19 15:10:26,618 – simple_example – DEBUG – debug message
2005-03-19 15:10:26,620 – simple_example – INFO – info message
2005-03-19 15:10:26,695 – simple_example – WARNING – warn message
2005-03-19 15:10:26,697 – simple_example – ERROR – error message
2005-03-19 15:10:26,773 – simple_example – CRITICAL – critical message

Handlers

handler对象负责发送相关的信息到指定目的地。可以通过addHandler()方法添加多个多handler
Handler.setLevel(lel):指定被处理的信息级别，低于lel级别的信息将被忽略
Handler.setFormatter()：给这个handler选择一个格式
Handler.addFilter(filt)、Handler.removeFilter(filt)：新增或删除一个filter对象

Formatters

Formatter对象设置日志信息最后的规则、结构和内容，默认的时间格式为%Y-%m-%d %H:%M:%S，下面是Formatter常用的一些信息

最后来个完整例子：

复制代码 代码如下:
import logging

# set up logging to file – see previous section for more details
logging.basicConfig(level=logging.DEBUG,
                    format=\’%(asctime)s %(name)-12s %(levelname)-8s %(message)s\’,
                    datefmt=\’%m-%d %H:%M\’,
                    filename=\’/temp/myapp.log\’,
                    filemode=\’w\’)
# define a Handler which writes INFO messages or higher to the sys.stderr
console = logging.StreamHandler()
console.setLevel(logging.INFO)
# set a format which is simpler for console use
formatter = logging.Formatter(\’%(name)-12s: %(levelname)-8s %(message)s\’)
# tell the handler to use this format
console.setFormatter(formatter)
# add the handler to the root logger
logging.getLogger(\’\’).addHandler(console)

# Now, we can log to the root logger, or any other logger. First the root…
logging.info(\’Jackdaws love my big sphinx of quartz.\’)

# Now, define a couple of other loggers which might represent areas in your
# application:

logger1 = logging.getLogger(\’myapp.area1\’)
logger2 = logging.getLogger(\’myapp.area2\’)

logger1.debug(\’Quick zephyrs blow, vexing daft Jim.\’)
logger1.info(\’How quickly daft jumping zebras vex.\’)
logger2.warning(\’Jail zesty vixen who grabbed pay from quack.\’)
logger2.error(\’The five boxing wizards jump quickly.\’)

运行后，在终端看到的结果

复制代码 代码如下:
root        : INFO     Jackdaws love my big sphinx of quartz.
myapp.area1 : INFO     How quickly daft jumping zebras vex.
myapp.area2 : WARNING  Jail zesty vixen who grabbed pay from quack.
myapp.area2 : ERROR    The five boxing wizards jump quickly.

在日志文件中的结果

复制代码 代码如下:
10-22 22:19 root         INFO     Jackdaws love my big sphinx of quartz.
10-22 22:19 myapp.area1  DEBUG    Quick zephyrs blow, vexing daft Jim.
10-22 22:19 myapp.area1  INFO     How quickly daft jumping zebras vex.
10-22 22:19 myapp.area2  WARNING  Jail zesty vixen who grabbed pay from quack.
10-22 22:19 myapp.area2  ERROR    The five boxing wizards jump quickly.
发现DEBUG信息只有在文件中出现，这是因为StreamHandler中setLevel是INFO，可以看出Logger.setLevel()和handler.setLevel()的区别

详细信息请参阅 http://docs.python.org/library/logging.html