技术

Python异常处理体系--学习（一）

Python内建异常体系结构

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 assignment

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