新建 SpringBoot 项目： springboot_jpa

配置 pom.xml 文件

<!-- springBoot JPA的起步依赖 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

<!-- MySQL连接驱动 -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>

配置 application.yml 文件

logging:
  level:
    # 配置日志
    com.atguigu.dao: debug
spring:
  datasource:
    username: root
    password: root
    url: jdbc:mysql://192.168.88.88:3306/springboot?useUnicode=true&characterEncoding=utf8
    driver-class-name: com.mysql.cj.jdbc.Driver

  #Redis
  redis:
    port: 6379
    host: 192.168.88.88

  jpa:
    database: mysql
    show-sql: true
    generate-ddl: true
    hibernate:
      ddl-auto: update
      naming_strategy: org.hibernate.cfg.ImprovedNamingStrategy

server:
  port: 1888

创建实体配置实体

package com.atguigu.domain;

import javax.persistence.*;

/**
 * @author: ShiGuang
 * @create: 2021-06-10 18:05
 * @description:
 */
@Entity
@Table(name = "user")
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;
    @Column(name = "username")
    private String username;
    @Column(name = "password")
    private String password;
    @Column(name = "name")
    private String name;

    //省略各种方法... ...
}

Controller 类

package com.atguigu.controller;

import com.atguigu.domain.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

/**
 * @author: ShiGuang
 * @create: 2021-06-10 18:10
 * @description:
 */
@RestController
@RequestMapping("/user")
public class UserController {

    @Autowired
    private UserService userService;

    @RequestMapping("/findAll")
    public List<User> findAll() {
        return userService.findUsers();
    }
}

Service 类

创建 UserService 接口

package com.atguigu.service;

import com.atguigu.domain.User;

import java.util.List;

/**
 * @author: ShiGuang
 * @create: 2021-06-10 18:12
 * @description:
 */
public interface UserService {
    List<User> findUsers();
}

创建实现类

@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserDao userDao;

    @Override
    public List<User> findUsers() {
        return userDao.findAll();
    }
}

UserRepository

package com.atguigu.dao;

import com.atguigu.domain.User;
import org.springframework.data.jpa.repository.JpaRepository;


/**
 * @author: ShiGuang
 * @create: 2021-06-10 18:20
 * @description:
 */
public interface UserDao extends JpaRepository<User, Integer> {

}