在当今的软件开发领域，Spring Boot 与 RESTful API 的结合已成为构建高效、可扩展 Web 应用的标配。本文将通过一个完整的项目示例，从知识铺垫到部署上线，带你一步步掌握 Spring Boot + RESTful 的开发流程。

一、知识铺垫

1.1 Spring Boot 简介

Spring Boot 是基于 Spring 框架的快速开发工具，它简化了 Spring 应用的初始搭建和开发过程。通过自动配置和起步依赖，开发者可以快速构建独立运行的、生产级别的 Spring 应用。

核心优势：

自动配置：根据项目依赖自动配置 Spring 组件，减少手动配置。
起步依赖：提供预定义的依赖组合，简化依赖管理。
嵌入式服务器：内置 Tomcat、Jetty 等服务器，无需额外部署。

1.2 RESTful API 简介

RESTful 是一种基于 HTTP 协议的软件架构风格，它强调资源的无状态操作和统一的接口设计。RESTful API 通过 HTTP 方法（GET、POST、PUT、DELETE 等）对资源进行操作，具有简洁、易扩展的特点。

核心原则：

资源：将数据抽象为资源，通过 URI 唯一标识。
无状态：每个请求包含所有必要信息，服务器不存储客户端状态。
统一接口：使用标准的 HTTP 方法对资源进行操作。

二、技术介绍

2.1 技术栈选择

Spring Boot：作为后端框架，提供快速开发和自动配置能力。
Spring Data JPA：简化数据库操作，支持 ORM 映射。
H2 数据库：内存数据库，便于开发和测试。
JUnit 5：单元测试框架。
Maven：项目构建和依赖管理工具。

2.2 项目需求

我们将开发一个简单的图书管理系统，提供以下 RESTful API：

获取所有图书：GET /api/books
根据 ID 获取图书：GET /api/books/{id}
添加图书：POST /api/books
更新图书：PUT /api/books/{id}
删除图书：DELETE /api/books/{id}

三、开发环境搭建

3.1 创建 Spring Boot 项目

使用 Spring Initializr 快速生成项目骨架（也可以建立maven项目手动配置pom文件）：

Project：Maven Project
Language：Java
Spring Boot：这里使用最新稳定版
Dependencies：添加 Spring Web、Spring Data JPA、H2 Database

3.2 项目结构

src/
├── main/
│   ├── java/com/example/bookstore/
│   │   ├── controller/      # 控制器层
│   │   ├── model/           # 实体类
│   │   ├── repository/      # 数据访问层
│   │   └── BookstoreApplication.java  # 主启动类
│   └── resources/
│       ├── application.properties  # 配置文件
│       └── data.sql       # 初始化数据（可选）
└── test/                    # 测试代码

3.3 配置文件

在 application.properties 中配置 H2 数据库：

# H2 数据库配置
spring.datasource.url=jdbc:h2:mem:bookstore
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=
spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
spring.h2.console.enabled=true  # 启用 H2 控制台

四、核心功能实现

4.1 实体类定义

创建 Book 实体类：

package com.example.bookstore.model;import jakarta.persistence.Entity;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;
import jakarta.persistence.Id;@Entity
public class Book {@Id@GeneratedValue(strategy = GenerationType.IDENTITY)private Long id;private String title;private String author;private Double price;public Book() {}public Book(String title, String author, Double price) {this.title = title;this.author = author;this.price = price;}// Getters and Setterspublic Long getId() { return id; }public void setId(Long id) { this.id = id; }public String getTitle() { return title; }public void setTitle(String title) { this.title = title; }public String getAuthor() { return author; }public void setAuthor(String author) { this.author = author; }public Double getPrice() { return price; }public void setPrice(Double price) { this.price = price; }
}

4.2 数据访问层

创建 BookRepository 接口，继承 JpaRepository：

package com.example.bookstore.repository;import com.example.bookstore.model.Book;
import org.springframework.data.jpa.repository.JpaRepository;public interface BookRepository extends JpaRepository<Book, Long> {// 继承 JpaRepository 后，自动拥有基本的 CRUD 方法，除特殊查询方式外，不用单独写
}

4.3 控制器层

创建 BookController，实现 RESTful API：

package com.example.bookstore.controller;import com.example.bookstore.model.Book;
import com.example.bookstore.repository.BookRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;import java.util.List;
import java.util.Optional;@RestController
@RequestMapping("/api/books")
public class BookController {@Autowiredprivate BookRepository bookRepository;// 获取所有图书@GetMappingpublic List<Book> getAllBooks() {return bookRepository.findAll();}// 根据 ID 获取图书@GetMapping("/{id}")public ResponseEntity<Book> getBookById(@PathVariable Long id) {Optional<Book> book = bookRepository.findById(id);return book.map(ResponseEntity::ok).orElseGet(() -> ResponseEntity.notFound().build());}// 添加图书@PostMappingpublic Book createBook(@RequestBody Book book) {return bookRepository.save(book);}// 更新图书@PutMapping("/{id}")public ResponseEntity<Book> updateBook(@PathVariable Long id, @RequestBody Book bookDetails) {return bookRepository.findById(id).map(book -> {book.setTitle(bookDetails.getTitle());book.setAuthor(bookDetails.getAuthor());book.setPrice(bookDetails.getPrice());Book updatedBook = bookRepository.save(book);return ResponseEntity.ok(updatedBook);}).orElseGet(() -> ResponseEntity.notFound().build());}// 删除图书@DeleteMapping("/{id}")public ResponseEntity<Void> deleteBook(@PathVariable Long id) {return bookRepository.findById(id).map(book -> {bookRepository.delete(book);return ResponseEntity.noContent().<Void>build();}).orElseGet(() -> ResponseEntity.notFound().build());}
}

4.4 初始化数据（可选）

在 src/main/resources/data.sql 中添加初始化数据：

INSERT INTO book (title, author, price) VALUES ('Spring in Action', 'Craig Walls', 49.99);
INSERT INTO book (title, author, price) VALUES ('Effective Java', 'Joshua Bloch', 45.00);

五、测试与部署

5.1 单元测试

使用 JUnit 5 编写单元测试，测试 BookController：

package com.example.bookstore.controller;import com.example.bookstore.model.Book;
import com.example.bookstore.repository.BookRepository;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;import java.util.Arrays;
import java.util.List;
import java.util.Optional;import static org.junit.jupiter.api.Assertions.*;
import static org.mockito.Mockito.*;class BookControllerTest {@Mockprivate BookRepository bookRepository;@InjectMocksprivate BookController bookController;@BeforeEachvoid setUp() {MockitoAnnotations.openMocks(this);}@Testvoid getAllBooks_ShouldReturnAllBooks() {// 准备测试数据Book book1 = new Book("Book 1", "Author 1", 10.0);Book book2 = new Book("Book 2", "Author 2", 20.0);List<Book> books = Arrays.asList(book1, book2);// 模拟行为when(bookRepository.findAll()).thenReturn(books);// 调用方法List<Book> result = bookController.getAllBooks();// 验证结果assertEquals(2, result.size());assertEquals("Book 1", result.get(0).getTitle());verify(bookRepository, times(1)).findAll();}@Testvoid getBookById_ShouldReturnBookWhenExists() {// 准备测试数据Book book = new Book("Book 1", "Author 1", 10.0);book.setId(1L);// 模拟行为when(bookRepository.findById(1L)).thenReturn(Optional.of(book));// 调用方法ResponseEntity<Book> response = bookController.getBookById(1L);// 验证结果assertEquals(HttpStatus.OK, response.getStatusCode());assertEquals("Book 1", response.getBody().getTitle());verify(bookRepository, times(1)).findById(1L);}@Testvoid getBookById_ShouldReturnNotFoundWhenBookDoesNotExist() {// 模拟行为when(bookRepository.findById(1L)).thenReturn(Optional.empty());// 调用方法ResponseEntity<Book> response = bookController.getBookById(1L);// 验证结果assertEquals(HttpStatus.NOT_FOUND, response.getStatusCode());verify(bookRepository, times(1)).findById(1L);}@Testvoid createBook_ShouldSaveBook() {// 准备测试数据Book book = new Book("New Book", "New Author", 30.0);Book savedBook = new Book("New Book", "New Author", 30.0);savedBook.setId(1L);// 模拟行为when(bookRepository.save(book)).thenReturn(savedBook);// 调用方法Book result = bookController.createBook(book);// 验证结果assertEquals(1L, result.getId());assertEquals("New Book", result.getTitle());verify(bookRepository, times(1)).save(book);}@Testvoid updateBook_ShouldUpdateBookWhenExists() {// 准备测试数据Book existingBook = new Book("Old Book", "Old Author", 10.0);existingBook.setId(1L);Book updatedBookDetails = new Book("Updated Book", "Updated Author", 20.0);Book updatedBook = new Book("Updated Book", "Updated Author", 20.0);updatedBook.setId(1L);// 模拟行为when(bookRepository.findById(1L)).thenReturn(Optional.of(existingBook));when(bookRepository.save(existingBook)).thenReturn(updatedBook);// 调用方法ResponseEntity<Book> response = bookController.updateBook(1L, updatedBookDetails);// 验证结果assertEquals(HttpStatus.OK, response.getStatusCode());assertEquals("Updated Book", response.getBody().getTitle());verify(bookRepository, times(1)).findById(1L);verify(bookRepository, times(1)).save(existingBook);}@Testvoid updateBook_ShouldReturnNotFoundWhenBookDoesNotExist() {// 准备测试数据Book updatedBookDetails = new Book("Updated Book", "Updated Author", 20.0);// 模拟行为when(bookRepository.findById(1L)).thenReturn(Optional.empty());// 调用方法ResponseEntity<Book> response = bookController.updateBook(1L, updatedBookDetails);// 验证结果assertEquals(HttpStatus.NOT_FOUND, response.getStatusCode());verify(bookRepository, times(1)).findById(1L);verify(bookRepository, never()).save(any());}@Testvoid deleteBook_ShouldDeleteBookWhenExists() {// 准备测试数据Book book = new Book("Book 1", "Author 1", 10.0);book.setId(1L);// 模拟行为when(bookRepository.findById(1L)).thenReturn(Optional.of(book));doNothing().when(bookRepository).delete(book);// 调用方法ResponseEntity<Void> response = bookController.deleteBook(1L);// 验证结果assertEquals(HttpStatus.NO_CONTENT, response.getStatusCode());verify(bookRepository, times(1)).findById(1L);verify(bookRepository, times(1)).delete(book);}@Testvoid deleteBook_ShouldReturnNotFoundWhenBookDoesNotExist() {// 模拟行为when(bookRepository.findById(1L)).thenReturn(Optional.empty());// 调用方法ResponseEntity<Void> response = bookController.deleteBook(1L);// 验证结果assertEquals(HttpStatus.NOT_FOUND, response.getStatusCode());verify(bookRepository, times(1)).findById(1L);verify(bookRepository, never()).delete(any());}
}