logging 文件日志
1. 例子
import logging
logging.basicConfig(filename='log.txt', #文件名
level=logging.DEBUG, #级别
format=u'时间:%(asctime)s\n级别:%(levelname)s\n消息:%(message)s\n', #日志格式
datefmt='%Y-%m-%d %H:%M:%S') # 时间格式
logging.debug(u'第一条记录')
logging.info(u'第二条记录')
2. 级别
日志所记录的消息可以划分为不同的级别，一般用以下几种预定义的级别。
每种级别有对应的值，可以用来比较级别的高低。
| 级别 | 值 |
|---|---|
| CRITICAL | 50 |
| ERROR | 40 |
| WARNING | 30 |
| INFO | 20 |
| DEBUG | 10 |
| NOTSET | 0 |
每个级别都有对应的方法，用小写字母，比如 logging.debug() , logging.info()，分别用来记录 DEBUG 级别和 INFO 级别的消息。
logging.basicConfig 中配置的级别可以用来过滤消息，比配置级别低的消息将被忽略，不会写入文件。
比如，如果一开始配置的是 level=logging.INFO ，那么调用 logging.debug() 处理的消息将被忽略，不会记录到文件。只有用 info() 或者 warning() 以及更高级别才会被记录。
3. 日志格式
格式化字符串支持如下参数:
| 参数 | 解释 |
|---|---|
| %(asctime)s | Human-readable time when the LogRecord was created. By default this is of the form '2003-07-08 16:49:45,896'. |
| %(created)f | Time when the LogRecord was created (as returned by time.time()). |
| %(filename)s | Filename portion of pathname. |
| %(funcName)s | Name of function containing the logging call. |
| %(levelname)s | Text logging level for the message ('DEBUG', 'INFO', 'WARNING', 'ERROR', 'CRITICAL'). |
| %(levelno)s | Numeric logging level for the message (DEBUG, INFO, WARNING, ERROR, CRITICAL). |
| %(lineno)d | Source line number where the logging call was issued (if available). |
| %(module)s | Module (name portion of filename). |
| %(msecs)d | Millisecond portion of the time when the LogRecord was created. |
| %(message)s | The logged message. |
| %(name)s | Name of the logger used to log the call. |
| %(pathname)s | Full pathname of the source file where the logging call was issued (if available). |
| %(process)d | Process ID (if available). |
| %(processName)s | Process name (if available). |
| %(relativeCreated)d | Time in milliseconds when the LogRecord was created, relative to the time the logging module was loaded. |
| %(thread)d | Thread ID (if available). |
| %(threadName)s | Thread name (if available). |
3. 时间格式
时间格式化字符串与time.strftime()使用相同的参数
| 参数 | 解释 |
|---|---|
| %a | Locale's abbreviated weekday name. |
| %A | Locale's full weekday name. |
| %b | Locale's abbreviated month name. |
| %B | Locale's full month name. |
| %c | Locale's appropriate date and time representation. |
| %d | Day of the month as a decimal number [01,31]. |
| %H | Hour (24-hour clock) as a decimal number [00,23]. |
| %I | Hour (12-hour clock) as a decimal number [01,12]. |
| %j | Day of the year as a decimal number [001,366]. |
| %m | Month as a decimal number [01,12]. |
| %M | Minute as a decimal number [00,59]. |
| %p | Locale's equivalent of either AM or PM. |
| %S | Second as a decimal number [00,61]. |
| %U | Week number of the year (Sunday as the first day of the week) as a decimal number [00,53]. |
| %w | Weekday as a decimal number [0(Sunday),6]. |
| %W | Week number of the year (Monday as the first day of the week) as a decimal number [00,53]. |
| %x | Locale's appropriate date representation. |
| %X | Locale's appropriate time representation. |
| %y | Year without century as a decimal number [00,99]. |
| %Y | Year with century as a decimal number. |
| %Z | Time zone name (no characters if no time zone exists). |
| %% | A literal '%' character. |
4. 另一种写法
麻烦一点，但是可以定制多个logger
import logging
logger = logging.getLogger(u'mylogger')
handler = logging.FileHandler(u'log1.txt')
formatter = logging.Formatter(u'时间:%(asctime)s\n级别:%(levelname)s\n消息:%(message)s\n')
handler.setFormatter(formatter)
logger.addHandler(handler)
logger.setLevel(logging.DEBUG)
logger.debug(u'第一条记录')
logger.info(u'第二条记录')
logger2 = logging.getLogger(u'mylogger2')
handler2 = logging.FileHandler(u'log2.txt')
formatter2 = logging.Formatter(u'时间:%(asctime)s\n级别:%(levelname)s\n消息:%(message)s\n')
handler2.setFormatter(formatter2)
logger2.addHandler(handler2)
logger2.setLevel(logging.DEBUG)
logger2.debug(u'第一条记录')
logger2.info(u'第二条记录')
