server:
  port: 80

@RestController
@RequestMapping("/")
public class DemoController {
    @Value("${server.port}")
    private String port;
    @GetMapping
    public String func() {
        return "server port: " + port;
    }
}

server:
  port: 80
logging:
  level: 
    root: warn

@RestController
@RequestMapping("/")
public class DemoController {
    @Autowired
    private Environment environment;
    @GetMapping
    public String func() {
        String port = environment.getProperty("server.port");
        String level = environment.getProperty("logging.level.root");
        return "server port: " + port + "\n"
                + "logging level: " + level;
    }
}

mybook:
  name: 《SpringBoot入門》
  price: 28.00
  tags: [編程, Java, Spring]

@Component
@ConfigurationProperties(prefix = "mybook")
public class Book {
    private String name;
    private Double price;
    private String[] tags;
	// 省略了成員方法
}

@RestController
@RequestMapping("/")
public class DemoController {
    @Autowired
    private Book book;
    @GetMapping
    public String func() {
        return book.toString();
    }
}

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-configuration-processor</artifactId>
</dependency>