spring-boot

Spring Boot Development Guide

Overview

Spring Boot is a rapid development framework based on the Spring framework. It provides features such as auto-configuration and starter dependencies, simplifying the development of Spring applications.

Core Features

1. Project Creation

Using Spring Initializr：

Visit https://start.spring.io/ or use an IDE plugin to create a project.

Using the CLI：

# 安装 Spring Boot CLI
brew install spring-boot

Create a project

spring init --dependencies=web,data-jpa,postgresql my-project

**Maven 项目结构**：

my-project/ ├── src/ │ ├── main/ │ │ ├── java/ │ │ │ └── com/example/ │ │ │ └── MyApplication.java │ │ └── resources/ │ │ ├── application.properties │ │ └── application.yml │ └── test/ ├── pom.xml └── README.md

### 2. 自动配置

Spring Boot 通过自动配置简化了配置工作。

**application.yml**：

```yaml
spring:
  application:
    name: my-app
  datasource:
    url: jdbc:postgresql://localhost:5432/mydb
    username: postgres
    password: password
    driver-class-name: org.postgresql.Driver
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true
  server:
    port: 8080

application.properties：

spring.application.name=my-app
spring.datasource.url=jdbc:postgresql://localhost:5432/mydb
spring.datasource.username=postgres
spring.datasource.password=password
spring.datasource.driver-class-name=org.postgresql.Driver
spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
server.port=8080

3. Dependency Injection

Using @Component：

@Component
public class UserService {
    public String getUserName(Long id) {
        return "User " + id;
    }
}

Using @Service：

@Service
public class UserService {
    private final UserRepository userRepository;

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

    public User findById(Long id) {
        return userRepository.findById(id)
            .orElseThrow(() -> new UserNotFoundException(id));
    }
}

Using @Repository：

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
    Optional<User> findByEmail(String email);
    List<User> findByNameContaining(String name);
}

4. Web Development

REST Controller：

@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 User getUserById(@PathVariable Long id) {
        return userService.findById(id);
    }

    @PostMapping
    public User createUser(@RequestBody User user) {
        return userService.save(user);
    }

    @PutMapping("/{id}")
    public User updateUser(@PathVariable Long id, @RequestBody User user) {
        return userService.update(id, user);
    }

    @DeleteMapping("/{id}")
    public void deleteUser(@PathVariable Long id) {
        userService.delete(id);
    }
}

Exception Handling：

@ControllerAdvice
public class GlobalExceptionHandler {
    @ExceptionHandler(UserNotFoundException.class)
    public ResponseEntity<ErrorResponse> handleUserNotFound(UserNotFoundException ex) {
        ErrorResponse error = new ErrorResponse(
            HttpStatus.NOT_FOUND.value(),
            ex.getMessage()
        );
        return new ResponseEntity<>(error, HttpStatus.NOT_FOUND);
    }
}

5. Data Access

JPA Entity：

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

    @Column(nullable = false)
    private String name;

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

    // Getters and Setters
}

Repository：

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
    Optional<User> findByEmail(String email);
    List<User> findByNameContaining(String name);

    @Query("SELECT u FROM User u WHERE u.email = :email")
    Optional<User> findByEmailCustom(@Param("email") String email);
}

Service：

@Service
@Transactional
public class UserService {
    private final UserRepository userRepository;

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

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

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

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

    public void delete(Long id) {
        userRepository.deleteById(id);
    }
}

6. Configuration Management

@ConfigurationProperties：

@ConfigurationProperties(prefix = "app")
@Data
public class AppProperties {
    private String name;
    private String version;
    private Database database;

    @Data
    public static class Database {
        private String host;
        private int port;
        private String name;
    }
}

Using Configuration：

app:
  name: my-app
  version: 1.0.0
  database:
    host: localhost
    port: 5432
    name: mydb

7. Security (Spring Security)

Dependencies：

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

Configuration：

@Configuration
@EnableWebSecurity
public class SecurityConfig {
    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        http
            .authorizeHttpRequests(auth -> auth
                .requestMatchers("/api/public/**").permitAll()
                .anyRequest().authenticated()
            )
            .httpBasic();
        return http.build();
    }
}

8. Testing

Unit Testing：

@SpringBootTest
class UserServiceTest {
    @Autowired
    private UserService userService;

    @Test
    void testFindById() {
        User user = userService.findById(1L)
            .orElseThrow();
        assertNotNull(user);
    }
}

Integration Testing：

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
@AutoConfigureMockMvc
class UserControllerTest {
    @Autowired
    private MockMvc mockMvc;

    @Test
    void testGetUser() throws Exception {
        mockMvc.perform(get("/api/users/1"))
            .andExpect(status().isOk())
            .andExpect(jsonPath("$.name").value("John"));
    }
}

Best Practices

1. Project Structure

com.example.myapp/
├── controller/      # 控制器
├── service/        # 服务层
├── repository/     # 数据访问层
├── entity/         # 实体类
├── dto/            # 数据传输对象
├── config/         # 配置类
└── exception/      # 异常类

2. Dependency Injection

• Prefer constructor injection
• Avoid using @Autowired field injection
• Use @RequiredArgsConstructor (Lombok)

3. Exception Handling

• Use @ControllerAdvice for global exception handling
• Define custom exception classes
• Return a unified error response format

4. Configuration Management

• Use application.yml instead of application.properties
• Distinguish between development, testing, and production environment configurations
• Use @ConfigurationProperties to bind configuration

Common Dependencies

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

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

<!-- PostgreSQL -->
<dependency>
    <groupId>org.postgresql</groupId>
    <artifactId>postgresql</artifactId>
</dependency>

<!-- Lombok -->
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
</dependency>

Example Prompts

• "Create a REST API project using Spring Boot"
• "How do I use JPA for data access in Spring Boot?"
• "How do I configure a database connection in Spring Boot?"
• "How do I implement global exception handling in Spring Boot?"
• "How do I use Spring Security in Spring Boot?"