Overview
Understanding the differences between Struts 1 and Struts 2 is crucial for Java developers working with MVC (Model-View-Controller) frameworks. Struts, developed by Apache, is a popular open-source framework for creating Java EE web applications. Struts 1 was the initial release, which later evolved into Struts 2 with significant improvements and changes. Knowing these differences helps in making informed decisions when migrating applications from Struts 1 to Struts 2 or starting new projects.
Key Concepts
- Architecture and Workflow: The fundamental structure and processing flow differences between the two frameworks.
- Action Classes: How actions are defined and managed in Struts 1 vs. Struts 2.
- Interceptors and Filters: The mechanisms for pre-processing and post-processing requests in both frameworks.
Common Interview Questions
Basic Level
- What are the main architectural differences between Struts 1 and Struts 2?
- How do action classes differ in Struts 1 and Struts 2?
Intermediate Level
- How do Struts 1 and Struts 2 handle form data differently?
Advanced Level
- Discuss the interceptor stack in Struts 2 and compare it with the filter approach in Struts 1.
Detailed Answers
1. What are the main architectural differences between Struts 1 and Struts 2?
Answer: Struts 1 follows the Model 2 approach of MVC where the controller is a servlet and actions are singletons, leading to thread-safety concerns. Struts 2, however, uses a more flexible and advanced architecture where actions are instantiated per request, eliminating thread-safety issues. Struts 2 also leverages an interceptor stack for request processing, unlike the rigid, servlet-based controller of Struts 1.
Key Points:
- Struts 1 controller is a servlet; Struts 2 uses a Filter as its controller.
- Struts 1 actions are singletons; Struts 2 actions are instantiated per request.
- Struts 2 supports an interceptor stack for flexible request processing.
Example:
// This example is not applicable in C# code as Struts is a Java-based framework.
// The key points and explanations provided are specific to Java's Struts framework.
2. How do action classes differ in Struts 1 and Struts 2?
Answer: In Struts 1, action classes extend the Action class, and there's a heavy reliance on inheritance. In contrast, Struts 2 action classes do not need to extend or implement any framework class or interface, promoting composition over inheritance. This makes Struts 2 actions more lightweight and flexible.
Key Points:
- Struts 1 actions extend Action class.
- Struts 2 actions need not extend or implement any framework class or interface.
- Struts 2 promotes composition over inheritance, making it more flexible.
Example:
// This example is not applicable in C# code as Struts is a Java-based framework.
// The key points and explanations provided are specific to Java's Struts framework.
3. How do Struts 1 and Struts 2 handle form data differently?
Answer: Struts 1 uses ActionForms to encapsulate form inputs, which requires a separate class for each form. Struts 2, however, uses Action properties directly to capture form data, eliminating the need for separate form classes and simplifying data handling.
Key Points:
- Struts 1 uses ActionForms to capture form data.
- Struts 2 eliminates ActionForms, using action properties directly.
- Struts 2 simplifies data handling by removing the need for separate form classes.
Example:
// This example is not applicable in C# code as Struts is a Java-based framework.
// The key points and explanations provided are specific to Java's Struts framework.
4. Discuss the interceptor stack in Struts 2 and compare it with the filter approach in Struts 1.
Answer: Struts 2 introduces an interceptor stack, a powerful mechanism allowing pre-processing and post-processing around action invocations. Interceptors can handle tasks like validation, file upload, and type conversion, which are executed in a specific order. In contrast, Struts 1 uses servlet filters for similar purposes, but with less flexibility and control compared to Struts 2's interceptor stack.
Key Points:
- Struts 2's interceptor stack offers a flexible way to process requests.
- Interceptors in Struts 2 can be customized and ordered as needed.
- Struts 1 relies on servlet filters, offering less flexibility than Struts 2's interceptors.
Example:
// This example is not applicable in C# code as Struts is a Java-based framework.
// The key points and explanations provided are specific to Java's Struts framework.
