Q&A: Handling HTTP errors: Use HttpServletResponse to set status codes and error messages. Configure Servlet: use web.xml file or annotations, annotations are recommended. Access request and session data: through the HttpServletRequest and HttpSession objects. Best practice: Use MVC pattern (Model-View-Controller) Use JSON and REST API (represent state transfer) Use security filter Use cache Practical case: Build a simple TODO list, including Maven project creation, Servlet writing, Pages are added, web.xml configured, and deployed to the web container.
Java Web Development in Action: FAQs and Best Practices
FAQs
Question: How to handle HTTP errors?
Answer: Using the HttpServletResponse
class, you can handle HTTP errors by setting the status code and error message. For example:
response.setStatus(500); response.getWriter().write("Internal Server Error");
Question: How to configure Servlet?
Answer: Servlet can be configured using web.xml
files or annotations. It is recommended to use annotations, which are more concise and easier to maintain. For example:
@WebServlet("/helloWorld") public class HelloWorldServlet extends HttpServlet { // ... }
Question: How to access request and session data?
Answer: You can use the HttpServletRequest
and HttpSession
objects to access request and session data. For example:
String name = request.getParameter("name"); HttpSession session = request.getSession();
Best Practice
Best Practice: Use the MVC pattern
MVC (Model-View-Control Server) pattern separates application logic from the presentation layer, thereby improving testability and maintainability.
Best Practice: Using JSON and the REST API
JSON (JavaScript Object Notation) is a lightweight interactive format. The RESTful API (Representing State Transfer) defines a set of standard operations called CRUD (Create, Read, Update, Delete) that can be used to interact with web services.
Best Practice: Use Security Filters
Security filters are used to protect applications from cross-site scripting (XSS), SQL injection, and other security vulnerabilities. infringement.
Best Practice: Use Caching
Caching can reduce the number of server-side requests, thereby improving performance.
Practical case: Build a simple TODO list
1. Create a project
Create a Maven project and add dependencies item.
<dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>4.0.1</version> <scope>provided</scope> </dependency>
2. Write Servlet
to create TodoServlet
, and process the /todos
URL path.
import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; @WebServlet("/todos") public class TodoServlet extends HttpServlet { // ... }
3. Add page
Create index.jsp
page to display the TODO list.
<html> <body> <h1>TODO List</h1> <form action="/todos" method="POST"> <input type="text" name="task" /> <input type="submit" value="Add" /> </form> <ul> <li>Item 1</li> <li>Item 2</li> </ul> </body> </html>
4. Deploy the project
Add web.xml
to the project to specify the Servlet and page. Deploy the project into a web container such as Tomcat or GlassFish.
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