Python捕获异常堆栈信息的几种方法

程序出错的时候，我们往往需要根据异常信息来找到具体出错的代码。简单地用print打印异常信息并不能很好地追溯出错的代码：

# -*- coding: utf-8 -*-
def foo(a, b):
    c = a + b
    raise ValueError('test')
    return c
def bar(a):
    print('a + 100:', foo(a, 100))
def main():
    try:
        bar(100)
    except Exception as e:
        print(repr(e))
if __name__ == '__main__':
    main()

输出：

ValueError('test',)

打印的异常信息不够详细，对错误追踪没有多大帮助。这时候异常堆栈信息就派上用场了。下面简单介绍几种打印异常堆栈信息的方法。

1.最简单的方法之一就是使用logging.exception

# -*- coding: utf-8 -*-
import logging
def foo(a, b):
    c = a + b
    raise ValueError('test')
    return c
def bar(a):
    print('a + 100:', foo(a, 100))
def main():
    try:
        bar(100)
    except Exception as e:
        logging.exception(e)
if __name__ == '__main__':
    main()

输出：

ERROR:root:test
Traceback (most recent call last):
  File "E:/git_work/scrapy_ppt/test.py", line 16, in main
    bar(100)
  File "E:/git_work/scrapy_ppt/test.py", line 11, in bar
    print('a + 100:', foo(a, 100))
  File "E:/git_work/scrapy_ppt/test.py", line 6, in foo
    raise ValueError('test')
ValueError: test

从异常堆栈信息中我们可以不费力气就找出错误代码是哪一行。

 

2.其它方法：

# -*- coding: utf-8 -*-
import traceback
import sys
def foo(a, b):
    c = a + b
    raise ValueError('test')
    return c
def bar(a):
    print('a + 100:', foo(a, 100))
def main():
    try:
        bar(100)
    except Exception as e:
        # 方法二
        traceback.print_exc()
        # 方法三
        msg = traceback.format_exc()
        print(msg)
        et, ev, tb = sys.exc_info()
        # 方法四
        traceback.print_tb(tb)
        # 方法五
        traceback.print_exception(et, ev, tb)
        # 方法六
        msg = traceback.format_exception(et, ev, tb)
        for m in msg:
            print(m)
if __name__ == '__main__':
    main()