Java Web Development in Action: FAQs and Best Practices
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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