前言
一、异常
1.1、忽略
1.2、捕获
1.3、异常链
1.4、自定义
1.5、抛出
二、异常的显示方式
2.1、打印信息
2.2、控制台警告
2.2、存储文件
前言相比java，python的异常和java中不同，python主要是防止程序异常被中止。一旦被catch后它还行往下执行。
一、异常 1.1、忽略pass这个关键字相当于一个占位符，好比TODO是一样的，只表示此行什么也不做，不代表其它的行代码不执行；
try:
print(5/0)
except ZeroDivisionError:
pass
print("ddd") #这行还是可以正常执行的
1.2、捕获
def parse_int(s):
try:
n = int(v)
except Exception as e:
print('Could not parse, Reason:', e)
parse_int('30') ##Reason: name 'v' is not defined
1.3、异常链
try:
client_obj.get_url(url)
except (URLError, ValueError, SocketTimeout):
client_obj.remove_url(url)
try:
client_obj.get_url(url)
except (URLError, ValueError):
client_obj.remove_url(url)
except SocketTimeout:
client_obj.handle_url_timeout(url)
try:
f = open(filename)
except OSError:
pass
1.4、自定义
class NetworkError(Exception):
pass
class HostnameError(NetworkError):
pass
class CustomError(Exception):
def __init__(self, message, status):
super().__init__(message, status)
self.message = message
self.status = status
try:
msg = s.recv()
except TimeoutError as e:
print(e)
except RuntimeError as e:
print(e.args)
1.5、抛出
try:
raise RuntimeError('It failed') #抛出新异常-raise Error
except RuntimeError as e:
print(e.args)
def example():
try:
int('N/A')
except ValueError:
print("Didn't work")
raise #捕获后再抛出
二、异常的显示方式
2.1、打印信息
try:
print(5/0)
except ZeroDivisionError as e:
print(e.args)
2.2、控制台警告
import warnings
warnings.simplefilter('always')
def func(x, y, log_file=None, debug=False):
if log_file is not None:
warnings.warn('log_file argument deprecated', DeprecationWarning)
func(1, 2, 'a')
#第一行日志输出warn内容，第二行输出代码内容
/Users/liudong/personCode/python/pythonTest/app/base/base_type.py:5: UserWarning: log_file argument deprecated
warnings.warn('log_file argument deprecated')
2.2、存储文件
import json;
numbers = [2,3,4,5,6];
fileName = "numbers.json";
with open(fileName, "w") as fileObj:
json.dump(numbers, fileObj);
with open(fileName, "r") as fileObj:
number1 = json.load(fileObj);
到此这篇关于Python包装异常处理方法的文章就介绍到这了,更多相关Python 异常处理内容请搜索易知道(ezd.cc)以前的文章或继续浏览下面的相关文章希望大家以后多多支持易知道(ezd.cc)！
