当使用AWS CloudFront预签名URL时，如果S3存储桶没有启用Origin Access Identity（OAI），可能会遇到问题。以下是解决该问题的代码示例：

1. 首先，确保您已经安装了AWS SDK for Python（boto3）。

2. 使用以下代码创建一个预签名URL：

import boto3
from botocore.exceptions import ClientError

def create_presigned_url(bucket_name, object_name, expiration=3600):
    """Generate a presigned URL to share an S3 object

    :param bucket_name: string
    :param object_name: string
    :param expiration: Time in seconds for the presigned URL to remain valid
    :return: Presigned URL as string. If error, returns None.
    """

    # Generate a presigned URL for the S3 object
    s3_client = boto3.client('s3')
    try:
        response = s3_client.generate_presigned_url('get_object',
                                                    Params={'Bucket': bucket_name,
                                                            'Key': object_name},
                                                    ExpiresIn=expiration)
    except ClientError as e:
        print(e)
        return None

    # The response contains the presigned URL
    return response

3. 使用以下代码获取预签名URL：

# 指定S3存储桶名称和对象键
bucket_name = 'your-bucket-name'
object_name = 'your-object-key'

# 创建预签名URL
presigned_url = create_presigned_url(bucket_name, object_name)

# 打印预签名URL
print(presigned_url)

确保将your-bucket-name和your-object-key替换为实际的存储桶名称和对象键。

通过使用以上代码，您将能够获取到CloudFront预签名URL，即使S3存储桶没有启用OAI。