Python中高效处理异常情况的实用技巧

```python

# Python异常处理实用技巧

## 1. 基础异常处理结构

```python

try:

# 可能引发异常的代码

result = 10 / 0

except ZeroDivisionError as e:

# 处理特定异常

print(f除零错误: {e})

except (ValueError, TypeError) as e:

# 处理多个异常

print(f值或类型错误: {e})

except Exception as e:

# 捕获所有其他异常

print(f未知错误: {e})

else:

# 如果没有异常发生

print(操作成功)

finally:

# 无论是否发生异常都会执行

print(清理操作)

```

## 2. 自定义异常类

```python

class CustomError(Exception):

自定义异常基类

def __init__(self, message, error_code=None):

self.message = message

self.error_code = error_code

super().__init__(self.message)

class ValidationError(CustomError):

数据验证异常

pass

def validate_age(age):

if age < 0 or age > 150:

raise ValidationError(年龄必须在0-150之间, INVALID_AGE)

try:

validate_age(-5)

except ValidationError as e:

print(f验证错误: {e.message} (代码: {e.error_code}))

```

## 3. 上下文管理器处理资源

```python

from contextlib import contextmanager

@contextmanager

def database_connection(connection_string):

connection = None

try:

connection = create_connection(connection_string)

yield connection

except DatabaseError as e:

print(f数据库错误: {e})

raise

finally:

if connection:

connection.close()

# 使用示例

with database_connection(db://localhost/mydb) as conn:

conn.execute_query(SELECT FROM users)

```

## 4. 异常链与重新抛出

```python

def process_data(data):

try:

return int(data)

except ValueError as e:

raise ProcessingError(f无法处理数据: {data}) from e

class ProcessingError(Exception):

pass

try:

process_data(abc)

except ProcessingError as e:

print(f处理错误: {e})

print(f原始异常: {e.__cause__})

```

## 5. 使用装饰器统一异常处理

```python

def handle_exceptions(func):

def wrapper(args, kwargs):

try:

return func(args, kwargs)

except ValueError as e:

print(f值错误: {e})

return None

except Exception as e:

print(f未预期错误: {e})

return None

return wrapper

@handle_exceptions

def risky_operation(x, y):

return x / y

result = risky_operation(10, 0) # 安全执行

```

## 6. 日志记录与异常处理结合

```python

import logging

logging.basicConfig(level=logging.INFO)

logger = logging.getLogger(__name__)

def safe_file_operation(filename):

try:

with open(filename, 'r') as file:

return file.read()

except FileNotFoundError:

logger.warning(f文件不存在: {filename})

return

except PermissionError:

logger.error(f没有权限访问文件: {filename})

raise

except Exception as e:

logger.exception(f读取文件时发生未知错误: {e})

raise

```

## 7. 使用else子句优化代码结构

```python

def process_user_data(user_data):

try:

data = json.loads(user_data)

except json.JSONDecodeError as e:

print(fJSON解析错误: {e})

return None

else:

# 只有在没有异常时才执行

if validate_user_data(data):

return create_user(data)

else:

print(数据验证失败)

return None

```

## 8. 异常处理最佳实践

```python

# 好的实践：具体异常处理

def good_practice():

try:

value = int(123)

except ValueError as e:

handle_error(e)

# 不好的实践：过于宽泛的异常捕获

def bad_practice():

try:

value = int(123)

except: # 捕获所有异常，不推荐

pass

# 使用异常层次结构

def handle_api_call():

try:

response = requests.get(https://api.example.com/data)

response.raise_for_status()

return response.json()

except requests.HTTPError as e:

if e.response.status_code == 404:

print(资源未找到)

elif e.response.status_code == 500:

print(服务器错误)

else:

print(fHTTP错误: {e})

except requests.ConnectionError:

print(网络连接错误)

except requests.Timeout:

print(请求超时)

```

## 9. 使用functools.singledispatch处理不同类型异常

```python

from functools import singledispatch

@singledispatch

def handle_error(exc):

默认异常处理器

print(f未处理的异常类型: {type(exc).__name__}: {exc})

@handle_error.register

def _(exc: ValueError):

print(f值错误处理: {exc})

@handle_error.register

def _(exc: TypeError):

print(f类型错误处理: {exc})

# 使用示例

try:

# 可能抛出异常的代码

pass

except Exception as e:

handle_error(e)

```

这些技巧可以帮助你编写更健壮、可维护的Python代码，有效处理各种异常情况。