Python 记录到 stdout 和 StringIO

Question

尝试 [see it running here]：

from sys import stdout, stderr
from cStringIO import StringIO
from logging import getLogger, basicConfig, StreamHandler

basicConfig(format='%(asctime)s %(name)-12s %(levelname)-8s %(message)s',
            datefmt='%m-%d %H:%M')

log = getLogger(__name__)
sio = StringIO()
console = StreamHandler(sio)

log.addHandler(console)
log.addHandler(StreamHandler(stdout))

log.info('Jackdaws love my big sphinx of quartz.')
print 'console.stream.read() = {!r}'.format(console.stream.read())

输出[标准输出]：

console.stream.read() = ''

预期输出 [stdout]：

[date] [filename] INFO Jackdaws love my big sphinx of quartz.
console.stream.read() = 'Jackdaws love my big sphinx of quartz.'

Answer 1

这里发生了两件事。

首先，root logger 实例化为 WARNING 级别，这意味着不会处理级别低于 WARNING 的消息。您可以使用Logger.setLevel(level) 设置级别，此处定义级别 - https://docs.python.org/2/library/logging.html#levels。

按照 cmets 的建议，日志级别也可以设置为：

basicConfig(level='INFO', ...)

其次，写入StringIO对象时，流中的位置设置在当前流的末尾。您需要倒回 StringIO 对象，然后才能从中读取。

console.stream.seek(0)
console.stream.read()

更简单，只需调用：

console.stream.getvalue()

完整代码：

from sys import stdout, stderr
from cStringIO import StringIO
from logging import getLogger, basicConfig, StreamHandler

basicConfig(format='%(asctime)s %(name)-12s %(levelname)-8s %(message)s',
            datefmt='%m-%d %H:%M')

log = getLogger(__name__)
log.setLevel("INFO")
sio = StringIO()
console = StreamHandler(sio)

log.addHandler(console)
log.addHandler(StreamHandler(stdout))

log.info('Jackdaws love my big sphinx of quartz.')
console.stream.seek(0)
print 'console.stream.read() = {!r}'.format(console.stream.read())