Snyk Code is a real-time SAST tool that helps Java developers identify vulnerabilities, including path traversal in file uploads, through static analysis and machine learning models. It scans code to identify potential security risks, such as using user-specified file paths without proper validation, which can lead to unauthorized access to restricted files and directories. To prevent path traversal vulnerabilities, developers should avoid using `file.getOriginalFilename()` and instead check if the normalized path starts with the intended upload folder. This can be done by normalizing the path and throwing an exception if it does not start with the expected directory. By implementing proper validation and using tools like Snyk Code, developers can help ensure the security of their Java applications and protect against potential attacks.