REST

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>at.aydin.academy</groupId>
        <artifactId>03rest-pair</artifactId>
        <version>1.0.0</version>
        <relativePath>../pom.xml</relativePath>
    </parent>
    <artifactId>rest-modern</artifactId>
    <packaging>jar</packaging>
    <name>REST Modern (Spring Boot)</name>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-validation</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

package at.aydin.lab.rest.modern;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

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

server.port=8082
management.endpoints.web.exposure.include=health,info

package at.aydin.lab.rest.modern;

import jakarta.validation.constraints.NotBlank;

public record Book(long id, @NotBlank String title) {
}

package at.aydin.lab.rest.modern;

import org.springframework.stereotype.Repository;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicLong;

@Repository
// Design Pattern: Repository
// Zweck: Der Controller kennt keine Details der Datenhaltung.
public class BookRepository {
    private final ConcurrentHashMap<Long, Book> books = new ConcurrentHashMap<>();
    private final AtomicLong sequence = new AtomicLong();
    public BookRepository() {
        save(new Book(0, "Modernes Enterprise Java"));
    }

    public List<Book> findAll() {
        return List.copyOf(books.values());
    }

    public Book save(Book input) {
        long id = input.id() == 0 ? sequence.incrementAndGet() : input.id();
        Book stored = new Book(id, input.title());
        books.put(id, stored);
        return stored;
    }
}

package at.aydin.lab.rest.modern;

import jakarta.validation.Valid;
import org.springframework.http.ResponseEntity;
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.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.util.UriComponentsBuilder;
import java.util.List;

@RestController
@RequestMapping("/api/books")
public class BookController {
    private final BookService service;
    public BookController(BookService service) {
        this.service = service;
    }

    @GetMapping
    public List<Book> all() {
        return service.findAll();
    }

    @PostMapping
    public ResponseEntity<Book> create(@Valid @RequestBody Book book, UriComponentsBuilder uriBuilder) {
        Book created = service.create(book);
        return ResponseEntity.created(uriBuilder.path("/api/books/{id}").build(created.id())).body(created);
    }
}

package at.aydin.lab.rest.modern;

import org.springframework.stereotype.Service;
import java.util.List;

@Service
// Design Pattern: Service Layer
// Zweck: Fachlogik bleibt unabhängig von HTTP.
public class BookService {
    private final BookRepository repository;
    public BookService(BookRepository repository) {
        this.repository = repository;
    }

    public List<Book> findAll() {
        return repository.findAll();
    }

    public Book create(Book book) {
        return repository.save(book);
    }
}

package at.aydin.lab.rest.modern;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
import org.springframework.test.context.bean.override.mockito.MockitoBean;
import org.springframework.test.web.servlet.MockMvc;
import java.util.List;
import static org.mockito.Mockito.when;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;

@WebMvcTest(BookController.class)
class BookControllerTest {
    @Autowired
    MockMvc mockMvc;
    @MockitoBean
    BookService service;
    @Test
    void returnsBooks() throws Exception {
        when(service.findAll()).thenReturn(List.of(new Book(1, "Testbuch")));
        mockMvc.perform(get("/api/books")).andExpect(status().isOk()).andExpect(jsonPath("$[0].title").value("Testbuch"));
    }
}