Spring Boot 3.x 实战指南

ClownF原创2024/1/20大约 2 分钟

Spring Boot 3.x 实战指南

Spring Boot 3.x 是 Spring 生态系统的重大更新，基于 Java 17 和 Jakarta EE 9+，带来了许多新特性。

快速开始

创建项目

使用 Spring Initializr 创建项目：

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>3.2.0</version>
</parent>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
</dependencies>

主应用类

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

核心特性

1. 自动配置

Spring Boot 根据 classpath 中的 jar 包自动配置应用：

@Configuration
@ConditionalOnClass(DataSource.class)
@EnableConfigurationProperties(DataSourceProperties.class)
public class DataSourceAutoConfiguration {
    
    @Bean
    @ConditionalOnMissingBean
    public DataSource dataSource(DataSourceProperties properties) {
        return properties.initializeDataSourceBuilder().build();
    }
}

2. 依赖注入

@Service
public class UserService {
    
    private final UserRepository userRepository;
    
    // 构造器注入（推荐）
    public UserService(UserRepository userRepository) {
        this.userRepository = userRepository;
    }
    
    public User findById(Long id) {
        return userRepository.findById(id)
            .orElseThrow(() -> new UserNotFoundException(id));
    }
}

3. RESTful API

@RestController
@RequestMapping("/api/users")
public class UserController {
    
    private final UserService userService;
    
    public UserController(UserService userService) {
        this.userService = userService;
    }
    
    @GetMapping("/{id}")
    public ResponseEntity<User> getUser(@PathVariable Long id) {
        User user = userService.findById(id);
        return ResponseEntity.ok(user);
    }
    
    @PostMapping
    public ResponseEntity<User> createUser(@RequestBody @Valid UserDTO dto) {
        User user = userService.create(dto);
        return ResponseEntity.status(HttpStatus.CREATED).body(user);
    }
}

配置管理

application.yml

spring:
  application:
    name: my-application
  
  datasource:
    url: jdbc:mysql://localhost:3306/mydb
    username: root
    password: secret
    
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true
    
server:
  port: 8080
  compression:
    enabled: true

配置类

@Configuration
@ConfigurationProperties(prefix = "app")
public class AppProperties {
    
    private String name;
    private String version;
    private Security security;
    
    // Getters and Setters
    
    public static class Security {
        private String secretKey;
        private int tokenExpiration;
        // Getters and Setters
    }
}

数据访问

Spring Data JPA

@Entity
@Table(name = "users")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    
    @Column(nullable = false, unique = true)
    private String username;
    
    @Column(nullable = false)
    private String password;
    
    // Constructors, Getters, Setters
}

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
    Optional<User> findByUsername(String username);
    
    @Query("SELECT u FROM User u WHERE u.email LIKE %:domain")
    List<User> findByEmailDomain(@Param("domain") String domain);
}

异常处理

@RestControllerAdvice
public class GlobalExceptionHandler {
    
    @ExceptionHandler(UserNotFoundException.class)
    public ResponseEntity<ErrorResponse> handleUserNotFound(
        UserNotFoundException ex
    ) {
        ErrorResponse error = new ErrorResponse(
            HttpStatus.NOT_FOUND.value(),
            ex.getMessage()
        );
        return ResponseEntity.status(HttpStatus.NOT_FOUND).body(error);
    }
    
    @ExceptionHandler(MethodArgumentNotValidException.class)
    public ResponseEntity<Map<String, String>> handleValidationErrors(
        MethodArgumentNotValidException ex
    ) {
        Map<String, String> errors = ex.getBindingResult()
            .getFieldErrors()
            .stream()
            .collect(Collectors.toMap(
                FieldError::getField,
                FieldError::getDefaultMessage
            ));
        return ResponseEntity.badRequest().body(errors);
    }
}

安全配置

@Configuration
@EnableWebSecurity
public class SecurityConfig {
    
    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        http
            .csrf(csrf -> csrf.disable())
            .authorizeHttpRequests(auth -> auth
                .requestMatchers("/api/public/**").permitAll()
                .requestMatchers("/api/admin/**").hasRole("ADMIN")
                .anyRequest().authenticated()
            )
            .sessionManagement(session -> session
                .sessionCreationPolicy(SessionCreationPolicy.STATELESS)
            );
        
        return http.build();
    }
}

测试

@SpringBootTest
@AutoConfigureMockMvc
class UserControllerTest {
    
    @Autowired
    private MockMvc mockMvc;
    
    @MockBean
    private UserService userService;
    
    @Test
    void shouldReturnUser() throws Exception {
        User user = new User(1L, "john", "john@example.com");
        when(userService.findById(1L)).thenReturn(user);
        
        mockMvc.perform(get("/api/users/1"))
            .andExpect(status().isOk())
            .andExpect(jsonPath("$.username").value("john"));
    }
}

最佳实践

使用构造器注入: 更容易测试，避免循环依赖
合理使用缓存: @Cacheable、@CacheEvict
异步处理: @Async 处理耗时操作
监控与健康检查: Actuator
API 文档: SpringDoc OpenAPI

总结

Spring Boot 3.x 为企业级 Java 应用开发提供了强大而灵活的框架，是现代 Java 开发的首选。