spring-boot-development

Spring Boot 开发技能

此技能基于官方 Spring Boot 文档，全面介绍如何使用自动配置、依赖注入、REST API、Spring Data、Spring Security 和企业级 Java 模式构建现代 Spring Boot 应用。

何时使用此技能

在以下情况下使用此技能：

• 构建企业级 REST API 和微服务
• 使用 Spring MVC 创建 Web 应用
• 使用 JPA 和数据库开发数据驱动型应用
• 使用 Spring Security 实现身份验证和授权
• 使用 Actuator 和监控构建可用于生产环境的应用
• 使用 Spring Boot 创建可扩展的后端服务
• 从传统 Spring 迁移到 Spring Boot
• 开发云原生应用
• 使用消息传递构建事件驱动系统
• 创建批处理应用

核心概念

自动配置

Spring Boot 会根据项目中添加的依赖自动配置应用，从而大幅减少样板配置。

自动配置的工作原理：

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

@SpringBootApplication 注解由以下注解组合而成：

• @Configuration：将类标记为 Bean 定义的来源
• @EnableAutoConfiguration：启用 Spring Boot 的自动配置机制
• @ComponentScan：启用当前包及其子包中的组件扫描

条件自动配置：

@Configuration
@ConditionalOnClass(DataSource.class)
@ConditionalOnProperty(name = "spring.datasource.url")
public class DataSourceAutoConfiguration {

    @Bean
    @ConditionalOnMissingBean
    public DataSource dataSource() {
        return DataSourceBuilder.create().build();
    }
}

自定义自动配置：

// Exclude specific auto-configurations
@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
public class MyApplication {
    // ...
}

// Or in application.properties
// spring.autoconfigure.exclude=org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration

依赖注入

Spring 的 IoC（控制反转）容器负责管理对象的创建和依赖注入。

构造函数注入（推荐）：

@Service
public class UserService {

    private final UserRepository userRepository;
    private final EmailService emailService;

    // Constructor injection - recommended approach
    public UserService(UserRepository userRepository, EmailService emailService) {
        this.userRepository = userRepository;
        this.emailService = emailService;
    }

    public User createUser(User user) {
        User saved = userRepository.save(user);
        emailService.sendWelcomeEmail(saved);
        return saved;
    }
}

字段注入（不推荐）：

@Service
public class UserService {

    @Autowired  // Avoid field injection
    private UserRepository userRepository;

    // Difficult to test and creates tight coupling
}

Setter 注入（可选依赖）：

@Service
public class UserService {

    private UserRepository userRepository;
    private EmailService emailService;

    @Autowired
    public void setUserRepository(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    @Autowired(required = false)
    public void setEmailService(EmailService emailService) {
        this.emailService = emailService;
    }
}

组件构造型注解：

@Component  // Generic component
public class MyComponent { }

@Service    // Business logic layer
public class MyService { }

@Repository // Data access layer
public class MyRepository { }

@Controller // Presentation layer (web)
public class MyController { }

@RestController // REST API controller
public class MyRestController { }

Spring Web（REST API）

使用 Spring MVC 注解构建 RESTful Web 服务。

基本 REST 控制器：

@RestController
@RequestMapping("/api/users")
public class UserController {

    private final UserService userService;

    public UserController(UserService userService) {
        this.userService = userService;
    }

    @GetMapping
    public List<User> getAllUsers() {
        return userService.findAll();
    }

    @GetMapping("/{id}")
    public ResponseEntity<User> getUserById(@PathVariable Long id) {
        return userService.findById(id)
            .map(ResponseEntity::ok)
            .orElse(ResponseEntity.notFound().build());
    }

    @PostMapping
    public ResponseEntity<User> createUser(@RequestBody @Valid User user) {
        User created = userService.save(user);
        URI location = ServletUriComponentsBuilder
            .fromCurrentRequest()
            .path("/{id}")
            .buildAndExpand(created.getId())
            .toUri();
        return ResponseEntity.created(location).body(created);
    }

    @PutMapping("/{id}")
    public ResponseEntity<User> updateUser(@PathVariable Long id,
                                          @RequestBody @Valid User user) {
        return userService.update(id, user)
            .map(ResponseEntity::ok)
            .orElse(ResponseEntity.notFound().build());
    }

    @DeleteMapping("/{id}")
    public ResponseEntity<Void> deleteUser(@PathVariable Long id) {
        if (userService.delete(id)) {
            return ResponseEntity.noContent().build();
        }
        return ResponseEntity.notFound().build();
    }
}

请求映射形式：

@RestController
@RequestMapping("/api/products")
public class ProductController {

    // Query parameters
    @GetMapping("/search")
    public List<Product> search(@RequestParam String name,
                               @RequestParam(required = false) String category) {
        return productService.search(name, category);
    }

    // Multiple path variables
    @GetMapping("/categories/{categoryId}/products/{productId}")
    public Product getProductInCategory(@PathVariable Long categoryId,
                                       @PathVariable Long productId) {
        return productService.findInCategory(categoryId, productId);
    }

    // Request headers
    @GetMapping("/{id}")
    public Product getProduct(@PathVariable Long id,
                             @RequestHeader("Accept-Language") String language) {
        return productService.find(id, language);
    }

    // Matrix variables
    @GetMapping("/{id}")
    public Product getProductWithMatrix(@PathVariable Long id,
                                       @MatrixVariable Map<String, String> filters) {
        return productService.findWithFilters(id, filters);
    }
}

响应处理：

@RestController
@RequestMapping("/api/orders")
public class OrderController {

    // Return different status codes
    @PostMapping
    public ResponseEntity<Order> createOrder(@RequestBody Order order) {
        Order created = orderService.create(order);
        return ResponseEntity.status(HttpStatus.CREATED).body(created);
    }

    // Custom headers
    @GetMapping("/{id}")
    public ResponseEntity<Order> getOrder(@PathVariable Long id) {
        Order order = orderService.findById(id);
        return ResponseEntity.ok()
            .header("X-Order-Version", order.getVersion().toString())
            .body(order);
    }

    // No content response
    @DeleteMapping("/{id}")
    public ResponseEntity<Void> deleteOrder(@PathVariable Long id) {
        orderService.delete(id);
        return ResponseEntity.noContent().build();
    }
}

Spring Data JPA

Spring Data JPA 为数据库访问提供仓库抽象。

实体定义：

@Entity
@Table(name = "users")
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(nullable = false, unique = true)
    private String email;

    @Column(nullable = false)
    private String name;

    @Column(name = "created_at", nullable = false, updatable = false)
    private LocalDateTime createdAt;

    @Column(name = "updated_at")
    private LocalDateTime updatedAt;

    @OneToMany(mappedBy = "user", cascade = CascadeType.ALL, orphanRemoval = true)
    private List<Order> orders = new ArrayList<>();

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "department_id")
    private Department department;

    @PrePersist
    protected void onCreate() {
        createdAt = LocalDateTime.now();
        updatedAt = LocalDateTime.now();
    }

    @PreUpdate
    protected void onUpdate() {
        updatedAt = LocalDateTime.now();
    }

    // Getters and setters
}

仓库接口：

@Repository
public interface UserRepository extends JpaRepository<User, Long> {

    // Query method - Spring Data generates implementation
    Optional<User> findByEmail(String email);

    List<User> findByNameContaining(String name);

    List<User> findByDepartmentId(Long departmentId);

    // Custom JPQL query
    @Query("SELECT u FROM User u WHERE u.email = ?1")
    Optional<User> findByEmailQuery(String email);

    // Named parameters
    @Query("SELECT u FROM User u WHERE u.name LIKE %:name% AND u.department.id = :deptId")
    List<User> searchByNameAndDepartment(@Param("name") String name,
                                        @Param("deptId") Long deptId);

    // Native SQL query
    @Query(value = "SELECT * FROM users WHERE email = ?1", nativeQuery = true)
    Optional<User> findByEmailNative(String email);

    // Modifying query
    @Modifying
    @Query("UPDATE User u SET u.name = :name WHERE u.id = :id")
    int updateUserName(@Param("id") Long id, @Param("name") String name);

    // Pagination and sorting
    Page<User> findByDepartmentId(Long departmentId, Pageable pageable);

    List<User> findByNameContaining(String name, Sort sort);
}

仓库用法：

@Service
public class UserService {

    private final UserRepository userRepository;

    public UserService(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    public Optional<User> findById(Long id) {
        return userRepository.findById(id);
    }

    public User save(User user) {
        return userRepository.save(user);
    }

    public List<User> findAll() {
        return userRepository.findAll();
    }

    public Page<User> findAll(int page, int size) {
        Pageable pageable = PageRequest.of(page, size, Sort.by("name"));
        return userRepository.findAll(pageable);
    }

    public boolean delete(Long id) {
        if (userRepository.existsById(id)) {
            userRepository.deleteById(id);
            return true;
        }
        return false;
    }
}

关系：

// One-to-Many
@Entity
public class Order {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "user_id")
    private User user;

    @OneToMany(mappedBy = "order", cascade = CascadeType.ALL, orphanRemoval = true)
    private List<OrderItem> items = new ArrayList<>();
}

// Many-to-Many
@Entity
public class Student {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @ManyToMany
    @JoinTable(
        name = "student_course",
        joinColumns = @JoinColumn(name = "student_id"),
        inverseJoinColumns = @JoinColumn(name = "course_id")
    )
    private Set<Course> courses = new HashSet<>();
}

配置

Spring Boot 使用 application.properties 或 application.yml 进行配置。

应用属性：

# Server configuration
server.port=8080
server.servlet.context-path=/api

# Database configuration
spring.datasource.url=jdbc:postgresql://localhost:5432/mydb
spring.datasource.username=user
spring.datasource.password=password
spring.datasource.driver-class-name=org.postgresql.Driver

# JPA configuration
spring.jpa.hibernate.ddl-auto=validate
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.PostgreSQLDialect

# Logging
logging.level.root=INFO
logging.level.com.example=DEBUG
logging.level.org.springframework.web=DEBUG
logging.pattern.console=%d{yyyy-MM-dd HH:mm:ss} - %msg%n

# Custom properties
app.name=My Application
app.version=1.0.0

应用 YAML：

server:
  port: 8080
  servlet:
    context-path: /api

spring:
  datasource:
    url: jdbc:postgresql://localhost:5432/mydb
    username: user
    password: password
    driver-class-name: org.postgresql.Driver

  jpa:
    hibernate:
      ddl-auto: validate
    show-sql: true
    properties:
      hibernate:
        format_sql: true
        dialect: org.hibernate.dialect.PostgreSQLDialect

logging:
  level:
    root: INFO
    com.example: DEBUG
    org.springframework.web: DEBUG

app:
  name: My Application
  version: 1.0.0

配置属性类：

@Configuration
@ConfigurationProperties(prefix = "app")
public class AppConfig {

    private String name;
    private String version;
    private Security security = new Security();

    public static class Security {
        private int tokenExpiration = 3600;
        private String secretKey;

        // Getters and setters
    }

    // Getters and setters
}

// Usage
@Service
public class MyService {

    private final AppConfig appConfig;

    public MyService(AppConfig appConfig) {
        this.appConfig = appConfig;
    }

    public void printConfig() {
        System.out.println("App: " + appConfig.getName());
        System.out.println("Version: " + appConfig.getVersion());
    }
}

特定环境的配置：

# application.properties (default)
spring.profiles.active=dev

# application-dev.properties
spring.datasource.url=jdbc:postgresql://localhost:5432/mydb_dev
logging.level.root=DEBUG

# application-prod.properties
spring.datasource.url=jdbc:postgresql://prod-server:5432/mydb_prod
logging.level.root=WARN

特定配置文件的 Bean：

@Configuration
public class DatabaseConfig {

    @Bean
    @Profile("dev")
    public DataSource devDataSource() {
        return new EmbeddedDatabaseBuilder()
            .setType(EmbeddedDatabaseType.H2)
            .build();
    }

    @Bean
    @Profile("prod")
    public DataSource prodDataSource() {
        return DataSourceBuilder.create().build();
    }
}

Spring Security

在应用中实现身份验证和授权。

基本安全配置：

@Configuration
@EnableWebSecurity
public class SecurityConfig {

    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        http
            .csrf().disable()
            .authorizeHttpRequests(auth -> auth
                .requestMatchers("/api/public/**").permitAll()
                .requestMatchers("/api/admin/**").hasRole("ADMIN")
                .requestMatchers("/api/users/**").hasAnyRole("USER", "ADMIN")
                .anyRequest().authenticated()
            )
            .httpBasic();

        return http.build();
    }

    @Bean
    public PasswordEncoder passwordEncoder() {
        return new BCryptPasswordEncoder();
    }
}

内存身份验证：

@Configuration
@EnableWebSecurity
public class SecurityConfig {

    @Bean
    public UserDetailsService userDetailsService(PasswordEncoder passwordEncoder) {
        UserDetails user = User.builder()
            .username("user")
            .password(passwordEncoder.encode("password"))
            .roles("USER")
            .build();

        UserDetails admin = User.builder()
            .username("admin")
            .password(passwordEncoder.encode("admin"))
            .roles("ADMIN", "USER")
            .build();

        return new InMemoryUserDetailsManager(user, admin);
    }
}

数据库身份验证：

@Service
public class CustomUserDetailsService implements UserDetailsService {

    private final UserRepository userRepository;

    public CustomUserDetailsService(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
        User user = userRepository.findByEmail(username)
            .orElseThrow(() -> new UsernameNotFoundException("User not found: " + username));

        return org.springframework.security.core.userdetails.User.builder()
            .username(user.getEmail())
            .password(user.getPassword())
            .roles(user.getRoles().toArray(new String[0]))
            .build();
    }
}

@Configuration
@EnableWebSecurity
public class SecurityConfig {

    private final CustomUserDetailsService userDetailsService;

    public SecurityConfig(CustomUserDetailsService userDetailsService) {
        this.userDetailsService = userDetailsService;
    }

    @Bean
    public DaoAuthenticationProvider authenticationProvider(PasswordEncoder passwordEncoder) {
        DaoAuthenticationProvider provider = new DaoAuthenticationProvider();
        provider.setUserDetailsService(userDetailsService);
        provider.setPasswordEncoder(passwordEncoder);
        return provider;
    }
}

JWT 身份验证：

@Component
public class JwtTokenProvider {

    @Value("${app.security.jwt.secret}")
    private String jwtSecret;

    @Value("${app.security.jwt.expiration}")
    private int jwtExpiration;

    public String generateToken(Authentication authentication) {
        UserPrincipal userPrincipal = (UserPrincipal) authentication.getPrincipal();

        Date now = new Date();
        Date expiryDate = new Date(now.getTime() + jwtExpiration);

        return Jwts.builder()
            .setSubject(Long.toString(userPrincipal.getId()))
            .setIssuedAt(now)
            .setExpiration(expiryDate)
            .signWith(SignatureAlgorithm.HS512, jwtSecret)
            .compact();
    }

    public Long getUserIdFromJWT(String token) {
        Claims claims = Jwts.parser()
            .setSigningKey(jwtSecret)
            .parseClaimsJws(token)
            .getBody();

        return Long.parseLong(claims.getSubject());
    }

    public boolean validateToken(String authToken) {
        try {
            Jwts.parser().setSigningKey(jwtSecret).parseClaimsJws(authToken);
            return true;
        } catch (SignatureException | MalformedJwtException | ExpiredJwtException |
                 UnsupportedJwtException | IllegalArgumentException ex) {
            return false;
        }
    }
}

@Component
public class JwtAuthenticationFilter extends OncePerRequestFilter {

    private final JwtTokenProvider tokenProvider;
    private final CustomUserDetailsService customUserDetailsService;

    public JwtAuthenticationFilter(JwtTokenProvider tokenProvider,
                                  CustomUserDetailsService customUserDetailsService) {
        this.tokenProvider = tokenProvider;
        this.customUserDetailsService = customUserDetailsService;
    }

    @Override
    protected void doFilterInternal(HttpServletRequest request,
                                   HttpServletResponse response,
                                   FilterChain filterChain) throws ServletException, IOException {
        try {
            String jwt = getJwtFromRequest(request);

            if (jwt != null && tokenProvider.validateToken(jwt)) {
                Long userId = tokenProvider.getUserIdFromJWT(jwt);

                UserDetails userDetails = customUserDetailsService.loadUserById(userId);
                UsernamePasswordAuthenticationToken authentication =
                    new UsernamePasswordAuthenticationToken(
                        userDetails, null, userDetails.getAuthorities()
                    );

                SecurityContextHolder.getContext().setAuthentication(authentication);
            }
        } catch (Exception ex) {
            logger.error("Could not set user authentication", ex);
        }

        filterChain.doFilter(request, response);
    }

    private String getJwtFromRequest(HttpServletRequest request) {
        String bearerToken = request.getHeader("Authorization");
        if (StringUtils.hasText(bearerToken) && bearerToken.startsWith("Bearer ")) {
            return bearerToken.substring(7);
        }
        return null;
    }
}

API 参考

常用注解

Spring 核心注解：

• @SpringBootApplication：主应用类
• @Component：通用组件
• @Service：服务层组件
• @Repository：数据访问层组件
• @Configuration：配置类
• @Bean：Bean 定义方法
• @Autowired：依赖注入
• @Value：注入属性值
• @Profile：基于配置文件的条件 Bean

Web 注解：

• @RestController：REST API 控制器
• @Controller：MVC 控制器
• @RequestMapping：映射 HTTP 请求
• @GetMapping：映射 GET 请求
• @PostMapping：映射 POST 请求
• @PutMapping：映射 PUT 请求
• @DeleteMapping：映射 DELETE 请求
• @PatchMapping：映射 PATCH 请求
• @PathVariable：提取路径变量
• @RequestParam：提取查询参数
• @RequestBody：提取请求体
• @RequestHeader：提取请求头
• @ResponseStatus：设置响应状态

数据注解：

• @Entity：JPA 实体
• @Table：表映射
• @Id：主键
• @GeneratedValue：自动生成的值
• @Column：列映射
• @OneToOne：一对一关系
• @OneToMany：一对多关系
• @ManyToOne：多对一关系
• @ManyToMany：多对多关系
• @JoinColumn：连接列
• @JoinTable：连接表

验证注解：

• @Valid：启用验证
• @NotNull：字段不能为 null
• @NotEmpty：字段不能为空
• @NotBlank：字段不能为全空白
• @Size：字符串或集合的大小
• @Min：最小值
• @Max：最大值
• @Email：电子邮件格式
• @Pattern：正则表达式模式

事务注解：

• @Transactional：启用事务管理
• @Transactional(readOnly = true)：只读事务

安全注解：

• @EnableWebSecurity：启用安全功能
• @PreAuthorize：方法级授权
• @PostAuthorize：方法执行后授权
• @Secured：基于角色的访问控制

异步与调度：

• @EnableAsync：启用异步处理
• @Async：异步方法
• @EnableScheduling：启用调度
• @Scheduled：定时方法

工作流模式

REST API 设计模式

完整的 CRUD REST API：

// Entity
@Entity
@Table(name = "products")
public class Product {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @NotBlank(message = "Name is required")
    private String name;

    @NotBlank(message = "Description is required")
    private String description;

    @NotNull(message = "Price is required")
    @Min(value = 0, message = "Price must be positive")
    private BigDecimal price;

    @NotNull(message = "Stock is required")
    @Min(value = 0, message = "Stock must be positive")
    private Integer stock;

    private LocalDateTime createdAt;
    private LocalDateTime updatedAt;

    @PrePersist
    protected void onCreate() {
        createdAt = LocalDateTime.now();
        updatedAt = LocalDateTime.now();
    }

    @PreUpdate
    protected void onUpdate() {
        updatedAt = LocalDateTime.now();
    }

    // Getters and setters
}

// Repository
@Repository
public interface ProductRepository extends JpaRepository<Product, Long> {
    List<Product> findByNameContaining(String name);
    List<Product> findByPriceBetween(BigDecimal minPrice, BigDecimal maxPrice);
}

// Service
@Service
@Transactional
public class ProductService {

    private final ProductRepository productRepository;

    public ProductService(ProductRepository productRepository) {
        this.productRepository = productRepository;
    }

    @Transactional(readOnly = true)
    public Page<Product> findAll(Pageable pageable) {
        return productRepository.findAll(pageable);
    }

    @Transactional(readOnly = true)
    public Optional<Product> findById(Long id) {
        return productRepository.findById(id);
    }

    public Product create(Product product) {
        return productRepository.save(product);
    }

    public Optional<Product> update(Long id, Product productDetails) {
        return productRepository.findById(id)
            .map(product -> {
                product.setName(productDetails.getName());
                product.setDescription(productDetails.getDescription());
                product.setPrice(productDetails.getPrice());
                product.setStock(productDetails.getStock());
                return productRepository.save(product);
            });
    }

    public boolean delete(Long id) {
        return productRepository.findById(id)
            .map(product -> {
                productRepository.delete(product);
                return true;
            })
            .orElse(false);
    }
}

// Controller
@RestController
@RequestMapping("/api/products")
public class ProductController {

    private final ProductService productService;

    public ProductController(ProductService productService) {
        this.productService = productService;
    }

    @GetMapping
    public Page<Product> getAllProducts(
            @RequestParam(defaultValue = "0") int page,
            @RequestParam(defaultValue = "10") int size,
            @RequestParam(defaultValue = "id") String sortBy) {
        Pageable pageable = PageRequest.of(page, size, Sort.by(sortBy));
        return productService.findAll(pageable);
    }

    @GetMapping("/{id}")
    public ResponseEntity<Product> getProductById(@PathVariable Long id) {
        return productService.findById(id)
            .map(ResponseEntity::ok)
            .orElse(ResponseEntity.notFound().build());
    }

    @PostMapping
    public ResponseEntity<Product> createProduct(@Valid @RequestBody Product product) {
        Product created = productService.create(product);
        URI location = ServletUriComponentsBuilder
            .fromCurrentRequest()
            .path("/{id}")
            .buildAndExpand(created.getId())
            .toUri();
        return ResponseEntity.created(location).body(created);
    }

    @PutMapping("/{id}")
    public ResponseEntity<Product> updateProduct(
            @PathVariable Long id,
            @Valid @RequestBody Product product) {
        return productService.update(id, product)
            .map(ResponseEntity::ok)
            .orElse(ResponseEntity.notFound().build());
    }

    @DeleteMapping("/{id}")
    public ResponseEntity<Void> deleteProduct(@PathVariable Long id) {
        if (productService.delete(id)) {
            return ResponseEntity.noContent().build();
        }
        return ResponseEntity.notFound().build();
    }
}

异常处理模式

全局异常处理器：

// Custom exceptions
public class ResourceNotFoundException extends RuntimeException {
    public ResourceNotFoundException(String message) {
        super(message);
    }
}

public class BadRequestException extends RuntimeException {
    public BadRequestException(String message) {
        super(message);
    }
}

// Error response
public class ErrorResponse {
    private LocalDateTime timestamp;
    private int status;
    private String error;
    private String message;
    private String path;

    // Constructors, getters, setters
}

// Global exception handler
@RestControllerAdvice
public class GlobalExceptionHandler {

    @ExceptionHandler(ResourceNotFoundException.class)
    public ResponseEntity<ErrorResponse> handleResourceNotFound(
            ResourceNotFoundException ex,
            WebRequest request) {
        ErrorResponse error = new ErrorResponse(
            LocalDateTime.now(),
            HttpStatus.NOT_FOUND.value(),
            "Not Found",
            ex.getMessage(),
            request.getDescription(false).replace("uri=", "")
        );
        return new ResponseEntity<>(error, HttpStatus.NOT_FOUND);
    }

    @ExceptionHandler(BadRequestException.class)
    public ResponseEntity<ErrorResponse> handleBadRequest(
            BadRequestException ex,
            WebRequest request) {
        ErrorResponse error = new ErrorResponse(
            LocalDateTime.now(),
            HttpStatus.BAD_REQUEST.value(),
            "Bad Request",
            ex.getMessage(),
            request.getDescription(false).replace("uri=", "")
        );
        return new ResponseEntity<>(error, HttpStatus.BAD_REQUEST);
    }

    @ExceptionHandler(MethodArgumentNotValidException.class)
    public ResponseEntity<Map<String, Object>> handleValidationErrors(
            MethodArgumentNotValidException ex) {
        Map<String, Object> errors = new HashMap<>();
        errors.put("timestamp", LocalDateTime.now());
        errors.put("status", HttpStatus.BAD_REQUEST.value());

        Map<String, String> fieldErrors = new HashMap<>();
        ex.getBindingResult().getFieldErrors().forEach(error ->
            fieldErrors.put(error.getField(), error.getDefaultMessage())
        );
        errors.put("errors", fieldErrors);

        return new ResponseEntity<>(errors, HttpStatus.BAD_REQUEST);
    }

    @ExceptionHandler(Exception.class)
    public ResponseEntity<ErrorResponse> handleGlobalException(
            Exception ex,
            WebRequest request) {
        ErrorResponse error = new ErrorResponse(
            LocalDateTime.now(),
            HttpStatus.INTERNAL_SERVER_ERROR.value(),
            "Internal Server Error",
            ex.getMessage(),
            request.getDescription(false).replace("uri=", "")
        );
        return new ResponseEntity<>(error, HttpStatus.INTERNAL_SERVER_ERROR);
    }
}

数据库集成模式

完整的数据库设置：

// application.yml
/*
spring:
  datasource:
    url: jdbc:postgresql://localhost:5432/mydb
    username: user
    password: password
  jpa:
    hibernate:
      ddl-auto: validate
    show-sql: true
    properties:
      hibernate:
        dialect: org.hibernate.dialect.PostgreSQLDialect
*/

// Flyway migrations (db/migration/V1__Create_users_table.sql)
/*
CREATE TABLE users (
    id BIGSERIAL PRIMARY KEY,
    email VARCHAR(255) NOT NULL UNIQUE,
    name VARCHAR(255) NOT NULL,
    password VARCHAR(255) NOT NULL,
    created_at TIMESTAMP NOT NULL,
    updated_at TIMESTAMP NOT NULL
);

CREATE INDEX idx_users_email ON users(email);
*/

// Entity with auditing
@Entity
@Table(name = "users")
@EntityListeners(AuditingEntityListener.class)
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(nullable = false, unique = true)
    private String email;

    @Column(nullable = false)
    private String name;

    @Column(nullable = false)
    private String password;

    @CreatedDate
    @Column(name = "created_at", nullable = false, updatable = false)
    private LocalDateTime createdAt;

    @LastModifiedDate
    @Column(name = "updated_at")
    private LocalDateTime updatedAt;

    // Getters and setters
}

// Enable JPA auditing
@Configuration
@EnableJpaAuditing
public class JpaConfig {
}

测试模式

单元测试：

@SpringBootTest
class UserServiceTest {

    @Mock
    private UserRepository userRepository;

    @InjectMocks
    private UserService userService;

    @BeforeEach
    void setUp() {
        MockitoAnnotations.openMocks(this);
    }

    @Test
    void testFindById_Success() {
        User user = new User();
        user.setId(1L);
        user.setEmail("[email protected]");

        when(userRepository.findById(1L)).thenReturn(Optional.of(user));

        Optional<User> result = userService.findById(1L);

        assertTrue(result.isPresent());
        assertEquals("[email protected]", result.get().getEmail());
        verify(userRepository, times(1)).findById(1L);
    }

    @Test
    void testFindById_NotFound() {
        when(userRepository.findById(1L)).thenReturn(Optional.empty());

        Optional<User> result = userService.findById(1L);

        assertFalse(result.isPresent());
    }
}

集成测试：

@SpringBootTest
@AutoConfigureMockMvc
@Transactional
class UserControllerIntegrationTest {

    @Autowired
    private MockMvc mockMvc;

    @Autowired
    private ObjectMapper objectMapper;

    @Autowired
    private UserRepository userRepository;

    @Test
    void testCreateUser_Success() throws Exception {
        User user = new User();
        user.setEmail("[email protected]");
        user.setName("Test User");

        mockMvc.perform(post("/api/users")
                .contentType(MediaType.APPLICATION_JSON)
                .content(objectMapper.writeValueAsString(user)))
            .andExpect(status().isCreated())
            .andExpect(jsonPath("$.email").value("[email protected]"))
            .andExpect(jsonPath("$.name").value("Test User"));
    }

    @Test
    void testGetUser_Success() throws Exception {
        User user = new User();
        user.setEmail("[email protected]");
        user.setName("Test User");
        User saved = userRepository.save(user);

        mockMvc.perform(get("/api/users/" + saved.getId()))
            .andExpect(status().isOk())
            .andExpect(jsonPath("$.id").value(saved.getId()))
            .andExpect(jsonPath("$.email").value("[email protected]"));
    }

    @Test
    void testGetUser_NotFound() throws Exception {
        mockMvc.perform(get("/api/users/999"))
            .andExpect(status().isNotFound());
    }
}

最佳实践

1. 使用构造函数注入

构造函数注入是推荐的依赖注入方式。

// Good - Constructor injection
@Service
public class UserService {
    private final UserRepository userRepository;
    private final EmailService emailService;

    public UserService(UserRepository userRepository, EmailService emailService) {
        this.userRepository = userRepository;
        this.emailService = emailService;
    }
}

// Bad - Field injection
@Service
public class UserService {
    @Autowired
    private UserRepository userRepository;
}

2. 对 API 请求／响应使用 DTO

不要通过 REST API 直接公开实体。

// DTO
public class UserDTO {
    private Long id;
    private String email;
    private String name;

    // No password field exposed
    // Getters and setters
}

// Mapper
@Component
public class UserMapper {
    public UserDTO toDTO(User user) {
        UserDTO dto = new UserDTO();
        dto.setId(user.getId());
        dto.setEmail(user.getEmail());
        dto.setName(user.getName());
        return dto;
    }

    public User toEntity(UserDTO dto) {
        User user = new User();
        user.setEmail(dto.getEmail());
        user.setName(dto.getName());
        return user;
    }
}

// Controller
@RestController
@RequestMapping("/api/users")
public class UserController {
    private final UserService userService;
    private final UserMapper userMapper;

    @GetMapping("/{id}")
    public ResponseEntity<UserDTO> getUser(@PathVariable Long id) {
        return userService.findById(id)
            .map(userMapper::toDTO)
            .map(ResponseEntity::ok)
            .orElse(ResponseEntity.notFound().build());
    }
}

3. 使用验证

始终验证输入数据。

// Entity with validation
@Entity
public class User {
    @NotBlank(message = "Email is required")
    @Email(message = "Email should be valid")
    private String email;

    @NotBlank(message = "Name is required")
    @Size(min = 2, max = 100, message = "Name must be between 2 and 100 characters")
    private String name;

    @NotBlank(message = "Password is required")
    @Size(min = 8, message = "Password must be at least 8 characters")
    private String password;
}

// Controller
@PostMapping
public ResponseEntity<User> createUser(@Valid @RequestBody User user) {
    // Validation happens automatically
    return ResponseEntity.ok(userService.save(user));
}

4. 正确使用事务

为服务方法设置适当的事务配置。

@Service
@Transactional
public class OrderService {

    @Transactional(readOnly = true)
    public List<Order> findAll() {
        return orderRepository.findAll();
    }

    @Transactional
    public Order createOrder(Order order) {
        // Multiple database operations in one transaction
        Order saved = orderRepository.save(order);
        inventoryService.decreaseStock(order.getItems());
        emailService.sendOrderConfirmation(saved);
        return saved;
    }
}

5. 使用分页

始终对大型数据集进行分页。

@GetMapping
public Page<Product> getProducts(
        @RequestParam(defaultValue = "0") int page,
        @RequestParam(defaultValue = "20") int size,
        @RequestParam(defaultValue = "id") String sortBy) {
    Pageable pageable = PageRequest.of(page, size, Sort.by(sortBy));
    return productService.findAll(pageable);
}

6. 全局处理异常

使用 @RestControllerAdvice 集中处理异常。

@RestControllerAdvice
public class GlobalExceptionHandler {

    @ExceptionHandler(ResourceNotFoundException.class)
    public ResponseEntity<ErrorResponse> handleNotFound(ResourceNotFoundException ex) {
        return ResponseEntity.status(HttpStatus.NOT_FOUND)
            .body(new ErrorResponse(ex.getMessage()));
    }
}

7. 使用日志记录

在整个应用中实现适当的日志记录。

@Service
public class UserService {
    private static final Logger logger = LoggerFactory.getLogger(UserService.class);

    public User createUser(User user) {
        logger.info("Creating user with email: {}", user.getEmail());
        try {
            User saved = userRepository.save(user);
            logger.info("User created successfully with id: {}", saved.getId());
            return saved;
        } catch (Exception e) {
            logger.error("Error creating user: {}", e.getMessage(), e);
            throw e;
        }
    }
}

8. 保护你的端点

实现适当的身份验证和授权。

@Configuration
@EnableWebSecurity
public class SecurityConfig {

    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        http
            .authorizeHttpRequests(auth -> auth
                .requestMatchers("/api/public/**").permitAll()
                .requestMatchers("/api/admin/**").hasRole("ADMIN")
                .anyRequest().authenticated()
            )
            .oauth2ResourceServer().jwt();

        return http.build();
    }
}

9. 使用数据库迁移

使用 Flyway 或 Liquibase 进行数据库版本控制。

-- V1__Create_users_table.sql
CREATE TABLE users (
    id BIGSERIAL PRIMARY KEY,
    email VARCHAR(255) NOT NULL UNIQUE,
    name VARCHAR(255) NOT NULL,
    created_at TIMESTAMP NOT NULL
);

-- V2__Add_password_column.sql
ALTER TABLE users ADD COLUMN password VARCHAR(255);

10. 监控你的应用

使用 Spring Boot Actuator 进行监控。

# application.properties
management.endpoints.web.exposure.include=health,info,metrics
management.endpoint.health.show-details=always

示例

有关详细代码示例，请参阅 EXAMPLES.md，内容包括：

• 基础 Spring Boot 应用
• 带 CRUD 操作的 REST API
• 使用 JPA 集成数据库
• 自定义查询与规范
• 请求验证
• 异常处理
• 使用 JWT 进行身份验证
• 基于角色的授权
• 文件上传／下载
• 使用 Redis 进行缓存
• 异步处理
• 定时任务
• 多数据库配置
• Actuator 与监控
• Docker 部署

概述

此 Spring Boot 开发技能涵盖：

1. 自动配置：根据依赖项自动配置
2. 依赖注入：IoC 容器、构造函数注入、组件构造型注解
3. REST API：控制器、请求映射、响应处理
4. Spring Data JPA：实体、存储库、关系、查询
5. 配置：属性、YAML、配置文件、自定义属性
6. 安全：身份验证、授权、JWT、基于角色的访问控制
7. 异常处理：全局异常处理、自定义异常
8. 测试：单元测试、集成测试、MockMvc
9. 最佳实践：DTO、验证、事务、分页、日志记录
10. 生产就绪：Actuator、监控、数据库迁移、部署

这些模式和示例基于 Spring Boot 官方文档（可信度评分：7.5），体现了现代企业级 Java 开发实践。