Chapter 20: Cookies and Sessions in Java

Set cookies, manage sessions, SameSite. In this chapter, you will learn cookies and sessions in depth with Java code examples, explanations, and best practices.

Overview

This chapter covers cookies and sessions for Kungfu.js developers using Java. We will start with the basics, move through practical examples, and end with advanced techniques and common pitfalls.

Why This Matters

Understanding cookies and sessions is essential because it is a core part of building web applications. Every real-world app needs to handle set cookies, manage sessions, samesite. Skipping this chapter would leave a gap in your knowledge that would cause problems later.

Code Example

Here is how to handle requests and responses in Java:

// Set a cookie
app.get('/set-cookie', (req) => {
    return {
        status: 200,
        headers: {
            'set-cookie': 'session_id=abc123; Path=/; HttpOnly; Max-Age=3600; SameSite=Strict'
        },
        body: 'Cookie set'
    };
});

// Read a cookie
app.get('/check', (req) => {
    const cookies = req.headers['cookie'] || '';
    // Parse cookies...
});

Common Mistakes

• Not reading the documentation: Always check the API reference when something does not work as expected.
• Skipping security: Never disable the default middleware unless you have a very good reason. Security is not optional.
• Not testing: Write tests for your handlers. Kungfu.js makes this easy with the built-in test utilities.

Summary

In this chapter, you learned about cookies and sessions in Java. You saw code examples, understood how things work under the hood, and learned about common mistakes to avoid.

What is Next?

In chapter 21, we will cover Database Connection: Connect to SQLite, PostgreSQL, MySQL, Supabase.