1.源码克隆：git clone https://github.com/spring-guides/gs-accessing-data-mysql.git
2.包含两个项目initial和complete，initial可以根据文档练习完善，complete是完整项目
3.功能描述：构建应用程序，并将其连接到MySQL数据库，使用 Spring Data JPA 来访问数据库
4.MySQL安装：https://blog.csdn.net/tongxin_tongmeng/article/details/127485630
5.MySQL数据库和用户创建及授权：
mysql> create database db_example; -- Creates the new database
mysql> create user 'springuser'@'%' identified by 'ThePassword'; -- Creates the user
mysql> grant all on db_example.* to 'springuser'@'%'; -- Gives all privileges to the new user on the newly created database
5.MySQL数据库连接配置(application.properties)：
spring.jpa.hibernate.ddl-auto=update
spring.datasource.url=jdbc:mysql://${MYSQL_HOST:localhost}:3306/db_example
spring.datasource.username=springuser
spring.datasource.password=ThePassword
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

源码分析

1.POM依赖
<dependencies>
	<!--https://blog.csdn.net/tongxin_tongmeng/article/details/128586690-->
	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-data-jpa</artifactId>
	</dependency>
	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-web</artifactId>
	</dependency>
	<!--https://blog.csdn.net/tongxin_tongmeng/article/details/128587053-->
	<dependency>
		<groupId>mysql</groupId>
		<artifactId>mysql-connector-java</artifactId>
		<scope>runtime</scope>
	</dependency>
	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-test</artifactId>
		<scope>test</scope>
	</dependency>
</dependencies>

2.POJO类
@Entity // This tells Hibernate to make a table out of this class
public class User {
	@Id
	@GeneratedValue(strategy=GenerationType.AUTO)
	private Integer id;

	private String name;

	private String email;

	public Integer getId() {
		return id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getEmail() {
		return email;
	}

	public void setEmail(String email) {
		this.email = email;
	}
}

3.接口类
public interface UserRepository extends CrudRepository<User, Integer> {

}

4.控制器
@Controller	// This means that this class is a Controller
@RequestMapping(path="/demo") // This means URL's start with /demo (after Application path)
public class MainController {
	@Autowired // This means to get the bean called userRepository
			   // Which is auto-generated by Spring, we will use it to handle the data
	private UserRepository userRepository;

	@PostMapping(path="/add") // Map ONLY POST Requests
	public @ResponseBody String addNewUser (@RequestParam String name
			, @RequestParam String email) {
		// @ResponseBody means the returned String is the response, not a view name
		// @RequestParam means it is a parameter from the GET or POST request

		User n = new User();
		n.setName(name);
		n.setEmail(email);
		userRepository.save(n);
		return "Saved";
	}

	@GetMapping(path="/all")
	public @ResponseBody Iterable<User> getAllUsers() {
		// This returns a JSON or XML with the users
		return userRepository.findAll();
	}
}