Spring Boot 4 与 Spring Framework 7 全面解析：新特性、升级要点与实战指南

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
class HelloWorldApiIntegrationTest {

    RestTestClient client;

    @BeforeEach
    void setUp(WebApplicationContext context) {
        client = RestTestClient.bindToApplicationContext(context)
            .build();
    }

    @Test
    void shouldFetchHelloV1() {
        client.get()
            .uri("/api/v1/hello")
            .exchange()
            .expectStatus()
            .isOk()
            .expectHeader()
            .contentTypeCompatibleWith(MediaType.TEXT_PLAIN)
            .expectBody(String.class)
            .consumeWith(message -> assertThat(message.getResponseBody()).containsIgnoringCase("hello"));
    }

}

@RestController
@RequestMapping("/hello")
public class HelloWorldController {

    // 版本1的接口，返回“Hello World”
    @GetMapping(version = "1", produces = MediaType.TEXT_PLAIN_VALUE)
    public String sayHelloV1() {
        return "Hello World";
    }

    // 版本2的接口，返回“Hi World”
    @GetMapping(version = "2", produces = MediaType.TEXT_PLAIN_VALUE)
    public String sayHelloV2() {
        return "Hi World";
    }
 
}

@RestController
@RequestMapping(path = "/hello", version = "3")
public class HelloWorldV3Controller {

    // 不用再给方法加version了，默认用控制器的版本3
    @GetMapping(produces = MediaType.TEXT_PLAIN_VALUE)
    public String sayHello() {
        return "Hey World";
    }

}

@Configuration
public class ApiConfig implements WebMvcConfigurer {

    @Override
    public void configureApiVersioning(ApiVersionConfigurer configurer) {
        // 用路径的第1段作为版本（比如/v1/里的1）
        configurer.usePathSegment(1);
    }

    @Override
    public void configurePathMatch(PathMatchConfigurer configurer) {
        // 给所有@RestController的接口加前缀/api/v{version}
        configurer.addPathPrefix("/api/v{version}", HandlerTypePredicate.forAnnotation(RestController.class));
    }

}

// 给这个接口加注解，指定服务名叫“christmasJoy”
@HttpServiceClient("christmasJoy")
public interface ChristmasJoyClient {

    // 用@GetExchange指定请求地址，相当于发GET请求到/greetings?random
    @GetExchange("/greetings?random")
    String getRandomGreeting();

}

@Configuration
// 导入自定义的注册器
@Import(HttpClientConfig.HelloWorldClientHttpServiceRegistrar.class)
public class HttpClientConfig {

    // 自定义注册器，负责扫描并注册HttpServiceClient接口
    static class HelloWorldClientHttpServiceRegistrar extends AbstractClientHttpServiceRegistrar {

        @Override
        protected void registerHttpServices(GroupRegistry registry, AnnotationMetadata metadata) {
            // 扫描com.baeldung.spring.mvc包下的HttpServiceClient接口
            findAndRegisterHttpServiceClients(registry, List.of("com.baeldung.spring.mvc"));
        }
    }

    // 配置“christmasJoy”这个服务的基础地址
    @Bean
    RestClientHttpServiceGroupConfigurer christmasJoyServiceGroupConfigurer() {
        return groups -> {
            groups.filterByName("christmasJoy") // 找到名叫christmasJoy的服务组
                .forEachClient((group, clientBuilder) -> {
                    // 设置基础URL
                    clientBuilder.baseUrl("https://christmasjoy.dev/api");
                });
        };
    }

}

@RestController
@RequestMapping(path = "/hello", version = "4")
@RequiredArgsConstructor // Lombok注解，自动生成构造器
public class HelloWorldV4Controller {

    // 注入ChristmasJoyClient
    private final ChristmasJoyClient christmasJoy;

    @GetMapping(produces = MediaType.TEXT_PLAIN_VALUE)
    public String sayHello() {
        // 调用客户端的方法，获取随机问候语
        return this.christmasJoy.getRandomGreeting();
    }

}

@HttpServiceClient("christmasJoy")
public interface ChristmasJoyClient {

    @GetExchange("/greetings?random")
    // 重试：最多试3次，第一次等100ms，之后每次等的时间翻倍，最多等1000ms
    @Retryable(maxAttempts = 3, delay = 100, multiplier = 2, maxDelay = 1000)
    // 并发限制：最多3个请求同时调用
    @ConcurrencyLimit(3)
    String getRandomGreeting();

}

@Component
@Slf4j
public class HelloWorldEventLogger {

    @Async // 标了这个就是异步执行
    @EventListener
    void logHelloWorldEvent(HelloWorldEvent event) {
        log.info("Hello World Event: {}", event.message());
    }

}

@Configuration
@Slf4j
public class TaskDecoratorConfiguration {

    // 第一个装饰器：打任务开始/结束日志，@Order标了2
    @Bean
    @Order(2)
    TaskDecorator loggingTaskConfigurator() {
        return runnable -> () -> {
            log.info("Running Task: {}", runnable); // 任务开始日志
            try {
                runnable.run(); // 执行实际任务
            } finally {
                log.info("Finished Task: {}", runnable); // 任务结束日志
            }
        };
    }

    // 第二个装饰器：算执行时间，@Order标了1（比上面先执行）
    @Bean
    @Order(1)
    TaskDecorator measuringTaskConfigurator() {
        return runnable -> () -> {
            final var ts1 = System.currentTimeMillis(); // 开始时间
            try {
                runnable.run(); // 执行实际任务
            } finally {
                final var ts2 = System.currentTimeMillis(); // 结束时间
                log.info("Finished within {}ms (Task: {})", ts2 - ts1, runnable); // 输出耗时
            }
        };
    }

}

Running Task: com.baeldung.spring.mvc.TaskDecoratorConfiguration$$Lambda/0x00000ff0014325f8@57e8609
Hello World Event: "Happy Christmas"
Finished within 0ms (Task: java.util.concurrent.FutureTask@bb978d6[Completed normally])
Finished Task: com.baeldung.spring.mvc.TaskDecoratorConfiguration$$Lambda/0x00000ff0014325f8@57e8609

@Configuration
public class ApiConfig implements WebMvcConfigurer {

    @Override
    public void configureApiVersioning(@NonNull ApiVersionConfigurer configurer) {
        configurer.usePathSegment(1);
    }

}