Spring Boot：快速构建Java应用

概述

Spring Boot是Spring的快速开发脚手架，它简化了Spring应用的配置和部署。通过自动配置和起步依赖，Spring Boot让Java应用的开发变得简单高效。

1. Spring Boot项目结构

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

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

2. RESTful Controller

import org.springframework.web.bind.annotation.*;
import java.util.List;

@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.create(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);
    }
}

3. 配置文件

server:
  port: 8080
spring:
  application:
    name: my-app
  datasource:
    url: jdbc:mysql://localhost:3306/mydb
    username: root
    password: 123456
app:
  name: MyApp
  version: 1.0.0

4. 数据访问

import org.springframework.data.jpa.repository.JpaRepository;

public interface UserRepository extends JpaRepository<User, Long> {
    User findByUsername(String username);
    List<User> findByAgeGreaterThan(int age);
}

@Service
public class UserService {
    private final UserRepository userRepository;

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

    public User findByUsername(String username) {
        return userRepository.findByUsername(username);
    }
}

5. 异常处理

import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.bind.annotation.RestControllerAdvice;

@RestControllerAdvice
public class GlobalExceptionHandler {

    @ExceptionHandler(UserNotFoundException.class)
    @ResponseStatus(HttpStatus.NOT_FOUND)
    public ErrorResponse handleUserNotFound(UserNotFoundException e) {
        return new ErrorResponse("USER_NOT_FOUND", e.getMessage());
    }

    @ExceptionHandler(Exception.class)
    @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
    public ErrorResponse handleGeneral(Exception e) {
        return new ErrorResponse("ERROR", "系统错误");
    }
}

最佳实践

1. 使用自动配置：充分利用Spring Boot的约定
2. 外部化配置：使用application.yml管理配置
3. 使用Actuator：监控应用健康状态
4. 使用Profile：区分不同环境配置
5. 使用Spring Data：简化数据访问

总结

Spring Boot是Java Web开发的首选框架，它简化了Spring应用的配置和部署。掌握Spring Boot的核心功能，可以快速构建和部署高质量的Java应用。