In servlets, the _________ framework can be used for advanced error handling and logging.
- ErrorLog
- ExceptionHandling
- Filter
- Log4j
In servlets, the Log4j framework can be used for advanced error handling and logging. Log4j provides a flexible logging framework for Java applications.
When handling a file upload, if an IOException occurs, how should the servlet respond and log the event?
- Ignore the exception
- Print the exception stack trace
- Send an appropriate HTTP error code
- Terminate the servlet
When an IOException occurs during a file upload, the servlet should send an appropriate HTTP error code to inform the client about the issue, and the event should be logged for troubleshooting and debugging purposes.
Describe the steps for setting up a custom error page for a specific type of exception in a servlet application.
- Define an error page in the servlet code
- Include a try-catch block in the servlet
- Redirect to a generic error page
- Use the
element in web.xml
To set up a custom error page for a specific type of exception in a servlet application, use the element in the web.xml file, specifying the exception type and the corresponding error page. This approach allows for centralized error handling and presentation.
What does thread-safe mean in the context of servlets?
- It means a servlet can handle multiple requests concurrently without any issues.
- It means a servlet can only handle one request at a time.
- It means a servlet cannot handle multiple requests.
- It means a servlet is immune to threading issues.
In the context of servlets, "thread-safe" means that a servlet can handle multiple requests concurrently without encountering threading issues.
Which method should be overridden to make a servlet thread-safe without synchronizing the entire service method?
- destroy()
- doPost()
- init()
- service()
To make a servlet thread-safe without synchronizing the entire service method, you should override the service() method and implement thread safety measures within it.
What is the risk of having instance variables in a servlet?
- Instance variables are mandatory in servlets.
- Instance variables can be accessed by multiple threads concurrently, leading to potential threading issues.
- Instance variables increase servlet performance.
- There is no risk.
The risk of having instance variables in a servlet is that they can be accessed by multiple threads concurrently, potentially causing threading issues.
How does the Servlet container typically handle concurrent requests to the same servlet?
- By creating a new instance of the servlet for each request
- By creating a new thread for each request
- By queuing the requests and processing them sequentially
- By using a single shared instance of the servlet
The Servlet container typically handles concurrent requests by using a single shared instance of the servlet, allowing multiple threads to access the same instance concurrently.
What is the impact of synchronization on servlet performance?
- Degrades performance
- Enhances scalability
- Improves performance
- No impact on performance
Synchronization can degrade servlet performance due to increased contention for locks. It's essential to use synchronization judiciously to prevent performance bottlenecks.
In what scenarios is it safe to have instance variables in a servlet?
- Always safe
- Never safe
- When shared across sessions
- When thread safety is guaranteed
Instance variables in a servlet are safe when they are shared across sessions and thread safety is guaranteed, ensuring that multiple requests can access them concurrently without issues.
The __________ pattern is often used to manage shared resources in a thread-safe manner in servlets.
- Decorator
- Factory
- Observer
- Singleton
The Singleton pattern is often used to manage shared resources in a thread-safe manner in servlets, ensuring that only one instance of the resource is created.