Python异常处理体系简介(1)

Python异常处理体系简介(1)

Python内建异常体系结构

The class hierarchy for built-in exceptions is：

BaseException
+-- SystemExit
+-- KeyboardInterrupt
+-- GeneratorExit
+-- Exception
+-- StopIteration
+-- StandardError
|    +-- BufferError
|    +-- ArithmeticError
|    |    +-- FloatingPointError
|    |    +-- OverflowError
|    |    +-- ZeroDivisionError
|    +-- AssertionError
|    +-- AttributeError
|    +-- EnvironmentError
|    |    +-- IOError
|    |    +-- OSError
|    |         +-- WindowsError (Windows)
|    |         +-- VMSError (VMS)
|    +-- EOFError
|    +-- ImportError
|    +-- LookupError
|    |    +-- IndexError
|    |    +-- KeyError
|    +-- MemoryError
|    +-- NameError
|    |    +-- UnboundLocalError
|    +-- ReferenceError
|    +-- RuntimeError
|    |    +-- NotImplementedError
|    +-- SyntaxError
|    |    +-- IndentationError
|    |         +-- TabError
|    +-- SystemError
|    +-- TypeError
|    +-- ValueError
|         +-- UnicodeError
|              +-- UnicodeDecodeError
|              +-- UnicodeEncodeError
|              +-- UnicodeTranslateError
+-- Warning
+-- DeprecationWarning
+-- PendingDeprecationWarning
+-- RuntimeWarning
+-- SyntaxWarning
+-- UserWarning
+-- FutureWarning
+-- ImportWarning
+-- UnicodeWarning
+-- BytesWarning

捕获异常的方式

方法一：捕获所有的异常

  ''' 捕获异常的第一种方式，捕获所有的异常 '''
    try:
        a = b
        b = c
    except Exception,data:
        print Exception,":",data
    '''输出：＜type 'exceptions.Exception'＞ : local variable 'b' 
referenced before assignment ''

方法二：采用traceback模块查看异常，需要导入traceback模块

   ''' 捕获异常的第二种方式，使用traceback查看异常 '''
try:
a = b
b = c
except:
print traceback.print_exc()
'''输出： Traceback (most recent call last):
File "test.py", line 20, in main
a = b
UnboundLocalError: local variable 'b' referenced before assignmen

方法三：采用sys模块回溯最后的异常

''' 捕获异常的第三种方式，使用sys模块捕获异常 '''
try:
a = b
b = c
except:
info = sys.exc_info()
print info
print info[0]
print info[1]
'''输出：
(＜type 'exceptions.UnboundLocalError'＞, UnboundLocalError("local 
variable 'b' referenced before assignment",),
＜traceback object at 0x00D243F0＞)
＜type 'exceptions.UnboundLocalError'＞
local variable 'b' referenced before assignment
'''