RestController and GetMapping

A class annotated with @RestController handles web requests. Each method annotated with @GetMapping("/path") answers GET requests to that path. Whatever the method returns is written into the response body (as JSON for objects).

package com.shopease.product;

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

@RestController
public class HelloController {

    @GetMapping("/hello")
    public String hello() {
        return "Welcome to ShopEase!";
    }
}

curl -i http://localhost:8080/hello

HTTP/1.1 200
Content-Type: text/plain;charset=UTF-8
Content-Length: 20

Welcome to ShopEase!

@RequestMapping on the class adds a prefix to every method in it:

@RestController
@RequestMapping("/api/products")
public class ProductController {

    @GetMapping            // GET /api/products
    public List<String> names() {
        return List.of("Boat Rockerz 450", "Clean Code", "Cotton T-Shirt");
    }

    @GetMapping("/count")  // GET /api/products/count
    public int count() {
        return 3;
    }
}