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Spring Boot 4 Complete Guide · Pelajaran

Membuat Pengendali REST

Rancang dan terapkan titik akhir RESTful menggunakan `@RestController` dan berbagai anotasi pemetaan.

Membuat Pengendali REST adalah pelajaran Spring Boot 4 Complete Guide gratis di CoddyKit. Ini adalah pelajaran 1 dari 4. Kamu bisa membaca pelajaran lengkapnya di bawah secara gratis — lalu praktikkan langsung di browser dengan editor kode bawaan dan tutor AI 24/7. Ini adalah bagian dari jalur belajar Spring Boot 4 Complete Guide, dan progresmu tersinkronisasi di web dan aplikasi CoddyKit. Kursus Spring Boot 4 Complete Guide mencakup 4 pelajaran total.

Bagian dari pelajaran ini belum diterjemahkan dan ditampilkan dalam bahasa Inggris.

Welcome to REST Controllers!

You're about to dive into building powerful web services with Spring Boot! Today, we'll learn how to create RESTful APIs, which are the backbone of modern web applications.

Think of a REST API as a standard way for different computer systems to talk to each other over the internet.

What are RESTful APIs?

REST stands for REpresentational State Transfer. It's an architectural style for networked applications.

  • Resources: Everything is a resource (e.g., a user, a product).
  • Unique Identifiers: Each resource has a unique URL (e.g., /users/123).
  • Standard Methods: We use standard HTTP methods like GET, POST, PUT, DELETE to interact with resources.

Spring Boot makes implementing these a breeze!

Introducing `@RestController`

In Spring Boot, the @RestController annotation is key to building RESTful web services. It's a special type of Spring component.

  • It tells Spring that this class handles incoming web requests.
  • It combines @Controller and @ResponseBody.

@ResponseBody means the return value of your methods should be directly bound to the web response body.

Your First GET Endpoint

Let's create a simple endpoint that responds to a GET request. GET requests are used to retrieve data.

We use the @GetMapping annotation to map HTTP GET requests to specific handler methods.

Runnable GET Example

Try running this simple Spring Boot application. It defines a /hello endpoint that returns a greeting.

package com.coddykit;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
public class MyApplication {
  public static void main(String[] args) {
    SpringApplication.run(MyApplication.class, args);
  }
}

@RestController
class HelloController {
  @GetMapping("/hello")
  public String sayHello() {
    return "Hello from CoddyKit!";
  }
}

Testing Your GET Endpoint

After running the previous code, your Spring Boot application starts on port 8080 by default.

You can access your new endpoint by opening a web browser and navigating to:

  • http://localhost:8080/hello

You should see the message "Hello from CoddyKit!" displayed.

Introducing `@PostMapping`

While GET is for retrieving data, POST requests are typically used to create new resources on the server.

The @PostMapping annotation maps HTTP POST requests to a specific method. When you send data, it often comes in the 'request body'.

We use @RequestBody to tell Spring to convert the incoming body into a Java object (or a simple String).

Runnable POST Example

Let's add a POST endpoint to our existing controller. This endpoint will accept a name in the request body and return a personalized greeting.

package com.coddykit;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
public class MyApplication {
  public static void main(String[] args) {
    SpringApplication.run(MyApplication.class, args);
  }
}

@RestController
class HelloController {
  @GetMapping("/hello")
  public String sayHello() {
    return "Hello from CoddyKit!";
  }

  @PostMapping("/greet")
  public String greetUser(@RequestBody String name) {
    return "Hello, " + name + "!";
  }
}

Path Variables with `@PathVariable`

Sometimes, you want to extract a value directly from the URL path itself. This is where path variables come in handy.

The @PathVariable annotation allows you to bind a URL template variable to a method parameter.

  • Example URL: /users/123
  • Here, 123 is a path variable representing a user ID.

Using Path Variables in Code

This example adds an endpoint that uses a path variable to greet a specific person whose name is part of the URL.

package com.coddykit;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
public class MyApplication {
  public static void main(String[] args) {
    SpringApplication.run(MyApplication.class, args);
  }
}

@RestController
class HelloController {
  @GetMapping("/hello")
  public String sayHello() {
    return "Hello from CoddyKit!";
  }

  @PostMapping("/greet")
  public String greetUser(@RequestBody String name) {
    return "Hello, " + name + "!";
  }

  @GetMapping("/greet/{name}")
  public String greetPathVar(@PathVariable String name) {
    return "Greetings, " + name + " from path!";
  }
}

Quick Check: Controller Basics

You've learned about `@RestController` and basic mapping annotations. Let's test your understanding.

Recap: Creating REST Controllers

Great job! You've taken your first steps into building RESTful APIs with Spring Boot:

  • We understood what RESTful APIs are and their purpose.
  • We learned about the fundamental @RestController annotation.
  • You implemented and tested endpoints for GET requests using @GetMapping.
  • You also created a basic POST endpoint with @PostMapping and used @RequestBody.
  • Finally, you saw how to extract dynamic data from URLs using @PathVariable.

Next, we'll dive deeper into handling various HTTP requests and crafting responses!

Pertanyaan yang Sering Diajukan

Apakah pelajaran “Membuat Pengendali REST” gratis?

Ya — teks lengkap “Membuat Pengendali REST” gratis dibaca di sini di web. Untuk praktiknya secara interaktif (editor kode bawaan dan tutor AI 24/7) dan buka sisa kursus Spring Boot 4 Complete Guide, upgrade ke CoddyKit PRO. Kursus Spring Boot 4 Complete Guide mencakup 4 pelajaran total.

Apa yang akan aku pelajari di “Membuat Pengendali REST”?

Rancang dan terapkan titik akhir RESTful menggunakan `@RestController` dan berbagai anotasi pemetaan. Kamu berlatih Spring Boot 4 Complete Guide dengan kode praktik yang langsung kamu jalankan di browser, dan tutor AI 24/7 menjawab pertanyaanmu saat kamu mengerjakan pelajaran ini.

Apakah aku perlu pengalaman untuk memulai Spring Boot 4 Complete Guide?

Tidak diperlukan pengalaman sebelumnya. Spring Boot 4 Complete Guide di CoddyKit dirancang untuk pemula hingga pelajar tingkat lanjut, jadi kamu bisa memulai di sini atau dari awal dan belajar sesuai kecepatan kamu sendiri. Ini adalah pelajaran 1 dari 4.

Berapa lama pelajaran “Membuat Pengendali REST” memakan waktu?

Sebagian besar pelajaran CoddyKit memakan waktu sekitar 5–10 menit. Setiap pelajaran ringkas dan interaktif, jadi kamu membuat kemajuan stabil dan melanjutkan dari tempat kamu tinggalkan di web dan aplikasi.

Bisakah aku menulis dan menjalankan kode dalam pelajaran Spring Boot 4 Complete Guide ini?

Ya. Setiap pelajaran Spring Boot 4 Complete Guide menyertakan editor kode bawaan, jadi kamu menulis dan menjalankan kode nyata langsung di browser dan mendapatkan umpan balik AI instan — tidak diperlukan penyiapan lokal.

Semua pelajaran dalam kursus ini

  1. Membuat Pengendali REST
  2. Menangani Permintaan dan Respons HTTP
  3. Validasi Masukan dan Penanganan Kesalahan
  4. Mendokumentasikan API REST dengan OpenAPI dan Swagger
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