try…except

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try:
    result = 1 / 0
    print(result)
except ArithmeticError:
    print("数学错误")   # 数学错误
  • 基础的一个处理方式
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try:
    result = 1 / 0
    print(result)
except ArithmeticError as e:
    print("数学错误")   # 数学错误
    print(type(e))  # <class 'ZeroDivisionError'>
    print(e)    # division by zero
  • 可以通过as关键字拿到异常对象做处理
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try:
    result = 1 / 0
    print(result)
except ZeroDivisionError:
    print("0不能作为除数")
except ArithmeticError:
    print("数学错误")
print("结束")

try:
    result = 1 / 0
    print(result)
except ArithmeticError:
    print("数学错误")
except ZeroDivisionError:
    print("0不能作为除数")
print("结束")
  • 注意异常对象之间的继承关系，子类的异常会被父类捕获
  • 异常捕获从上到下，被捕获后就跳出了，所以不要把子类异常放到父类异常后面，当然IDE也会有语法提示
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try:
    result = 1 / 0
    print(result)
except TypeError:
    print("运行出错了")
except ZeroDivisionError:
    print("运行出错了")
except ValueError:
    print("运行出错了")

try:
    result = 1 / 0
    print(result)
except (TypeError, ZeroDivisionError, ValueError):
    print("运行出错了")
  • 如果有多个异常的处理方式相同可以直接把异常对象放到元组中
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try:
    result = 1 / 0
    print(result)
except (TypeError, ValueError):
    print("类型错误或值错误")
# except:
except Exception:
    print("其它错误")
  • 最后接一个Exception或者直接except来捕获所有异常

else从句

如果没有异常发生则会执行的逻辑

finally从句

无论什么情况下都需要执行的逻辑

raise

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try:
    raise ZeroDivisionError('0不能作为除数')
except ZeroDivisionError as err:
    print(err)
  • 手动抛出异常

自定义异常

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class MyException(Exception):
    def __init__(self, msg1, msg2):
        self.msg1 = msg1
        self.msg2 = msg2


try:
    raise MyException('123', 'abc')
except MyException as err:
    print(err)

获取异常信息

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import sys
import traceback

def f1():
    print(1 / 0)

def f2():
    try:
        f1()
    except ZeroDivisionError:
        ex_type, ex_value, ex_traceback = sys.exc_info()

        print('异常的类型：%s' % ex_type)
        print('异常的错误信息：%s' % ex_value)
        print('异常调用堆栈的跟踪信息：%s' % ex_traceback)

        tb = traceback.extract_tb(ex_traceback)
        print(tb)

        for filename, linenum, funcname, source in tb:
            print('文件名：%s' % filename)
            print('行数：%s' % linenum)
            print('函数名：%s' % funcname)
            print('源码：%s' % source)

f2()