装饰器如何统一处理函数异常？实现重试机制的代码模板是怎样的？

import functools
import time
import logging

logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(levelname)s - %(message)s')

def retry(max_retries=3, delay=1, logger=None):
    """
    一个通用的重试装饰器，可以自定义重试次数、延迟时间和日志记录器。
    """
    def decorator_retry(func):
        @functools.wraps(func)
        def wrapper_retry(*args, **kwargs):
            retries = 0
            while retries < max_retries:
                try:
                    return func(*args, **kwargs)
                except Exception as e:
                    retries += 1
                    log_message = f"Function {func.__name__} failed with error: {e}, retrying ({retries}/{max_retries})..."
                    if logger:
                        logger.warning(log_message)
                    else:
                        logging.warning(log_message)
                    time.sleep(delay)
            # 如果所有重试都失败了，可以选择抛出异常或返回默认值
            raise Exception(f"Function {func.__name__} failed after {max_retries} retries.")

        return wrapper_retry
    return decorator_retry


def exception_handler(default_value=None, logger=None):
    """
    一个简单的异常处理装饰器，可以记录日志并返回默认值。
    """
    def decorator_exception_handler(func):
        @functools.wraps(func)
        def wrapper_exception_handler(*args, **kwargs):
            try:
                return func(*args, **kwargs)
            except Exception as e:
                log_message = f"Function {func.__name__} raised an exception: {e}"
                if logger:
                    logger.error(log_message)
                else:
                    logging.error(log_message)
                return default_value  # 返回默认值
        return wrapper_exception_handler
    return decorator_exception_handler


@retry(max_retries=3, delay=2, logger=logging)  # 使用retry装饰器，最多重试3次，每次间隔2秒
@exception_handler(default_value="Error", logger=logging) # 使用exception_handler装饰器，发生异常时返回"Error"
def might_fail(attempt):
    """
    一个可能失败的函数，用于演示。
    """
    print(f"Attempt {attempt}: Trying to execute might_fail...")
    if attempt < 2:
        raise ValueError(f"Simulated failure on attempt {attempt}")
    return f"Success on attempt {attempt}"


# 示例用法
if __name__ == "__main__":
    for i in range(3):
        try:
            result = might_fail(i)
            print(f"Result: {result}")
            break
        except Exception as e:
            print(f"Main block caught an exception: {e}")

import functools
import time
import logging
import requests

logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(levelname)s - %(message)s')

def specific_exception_handler(func):
    """
    针对特定异常类型的处理装饰器。
    """
    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        try:
            return func(*args, **kwargs)
        except requests.exceptions.RequestException as e:
            logging.error(f"Network error in {func.__name__}: {e}")
            # 可以选择重试网络请求，或者返回一个特定的错误值
            return None
        except ValueError as e:
            logging.error(f"Value error in {func.__name__}: {e}")
            raise  # 重新抛出ValueError，因为这通常是输入错误，不应该被忽略
        except Exception as e:
            logging.error(f"Unexpected error in {func.__name__}: {e}")
            return None  # 对于其他未知的异常，返回None
    return wrapper

@specific_exception_handler
def fetch_data(url):
    """
    模拟获取数据的函数，可能会抛出网络请求异常或ValueError。
    """
    print(f"Fetching data from {url}...")
    response = requests.get(url, timeout=5)
    response.raise_for_status()  # 如果响应状态码不是200，则抛出HTTPError
    return response.json()


if __name__ == "__main__":
    try:
        data = fetch_data("https://api.example.com/data")  # 假设这是一个有效的API endpoint
        print(f"Data: {data}")
    except Exception as e:
        print(f"Main block caught an exception: {e}")

    try:
        data = fetch_data("invalid_url")  # 模拟一个无效的URL，会抛出requests.exceptions.RequestException
        print(f"Data: {data}")
    except Exception as e:
        print(f"Main block caught an exception: {e}")