@RequestParam for query strings in Spring Boot - Mini Project: Build & Apply

Using @RequestParam for Query Strings in Spring Boot

📖 Scenario: You are building a simple Spring Boot web application that greets users based on their name passed in the URL query string.

🎯 Goal: Create a Spring Boot controller that reads a name parameter from the query string using @RequestParam and returns a greeting message.

📋 What You'll Learn

Create a Spring Boot controller class named GreetingController

Add a method greet that handles GET requests at /greet

Use @RequestParam to get the name query parameter

Return a greeting message including the name value

Set a default value for name as Guest if not provided

💡 Why This Matters

🌍 Real World

Web applications often need to read user input from URL query strings to customize responses, such as search filters or user greetings.

💼 Career

Understanding @RequestParam is essential for backend developers working with Spring Boot to handle HTTP requests and build REST APIs.

1

Create the GreetingController class

Create a public class called GreetingController annotated with @RestController.

Spring Boot

@RestController
// Your code here

Need a hint?

Use @RestController to make the class a REST controller.

2

Add the greet method with @GetMapping

Inside GreetingController, add a public method called greet that returns a String. Annotate it with @GetMapping("/greet").

Spring Boot

import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.bind.annotation.GetMapping;

@RestController
public class GreetingController {

    // Your code here
}

Need a hint?

Use @GetMapping("/greet") to map GET requests to the method.

3

Add @RequestParam to get the name query parameter

Modify the greet method to accept a String parameter called name annotated with @RequestParam(name = "name", defaultValue = "Guest").

Spring Boot

import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;

@RestController
public class GreetingController {

    @GetMapping("/greet")
    public String greet(@RequestParam(name = "name", defaultValue = "Guest") String name) {
        // Your code here
    }
}

Need a hint?

Use @RequestParam to read the query string parameter name with a default value.

4

Return a greeting message including the name

In the greet method, return a String that says "Hello, " followed by the name parameter.

Spring Boot

import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;

@RestController
public class GreetingController {

    @GetMapping("/greet")
    public String greet(@RequestParam(name = "name", defaultValue = "Guest") String name) {
        // Your code here
    }
}

Need a hint?

Use string concatenation to create the greeting message.