The response header Content-Disposition is crucial for indicating a file download rather than display.

For secure file uploads, it's essential to validate both the file type and content to ensure the uploaded file is safe and meets the required criteria.

To handle multiple file uploads, a servlet may use the JavaBeans Activation Framework (JAF) API to work with various types of data, including files.

To handle multipart/form-data requests for file uploading in servlets, the request.getPart() method is used to retrieve the uploaded file data.

In servlets, the InputStream obtained using request.getInputStream() is commonly used to facilitate the reading of file data sent by a client.

To ensure the safe and correct download of files with different character encodings, set the character encoding in the response header using response.setCharacterEncoding().

The servlet container differentiates between authenticated and unauthenticated users through the use of cookies, which store information about the user's session and authentication status.

The Java Authentication and Authorization Service (JAAS) is responsible for managing security in a Java EE environment, providing a framework for user authentication and authorization.

The web.xml security constraints define access control rules for web resources. They specify who can access a particular resource and under what conditions.

To manage memory efficiently during file upload, a streaming approach is recommended, allowing the servlet to process the file in chunks rather than loading the entire file into memory.