1. 创建一个Spring工程

2.配置application文件

spring.datasource.driver-class-name= com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/test2?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC
spring.datasource.username=root
spring.datasource.password=

3.创建实体类Piano

1.定义好属性并设置setget方法

2.添加@Entity && @Table(name = "piano")注解

3.添加@Id && @GeneratedValue(strategy = GenerationType.IDENTITY)

4.连接数据库

完成

package com.test.piano.entity;import javax.persistence.*;@Entity
@Table(name = piano)
public class piano {private int id;private String brand;private String price;private String pic;@Id@GeneratedValue(strategy = GenerationType.IDENTITY)public int getId() {return id;}public void setId(int id) {this.id = id;}public String getBrand() {return brand;}public void setBrand(String brand) {this.brand = brand;}public String getPrice() {return price;}public void setPrice(String price) {this.price = price;}public String getPic() {return pic;}public void setPic(String pic) {this.pic = pic;}
}

5.创建Dao和Service的包

6.在Dao中创建一个接口并继承JpaRepository,然后指定实体类piano和主键的类型Integer

public interface pianoRepository extends JpaRepository<piano,Integer>

7.在Service中创建类PianoService用于实现增删改查

8.添加注解

@Service表示是业务逻辑层
@Transactional(readOnly = false)
readOnly=true表明所注解的方法或类只是读取数据。
readOnly=false表明所注解的方法或类是增加，删除，修改数据。

4.创建Controller类

package com.test.piano.controller;import com.test.piano.entity.piano;
import com.test.piano.service.PianoService;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;import javax.annotation.Resource;
import java.util.List;/*** @date 2020/3/24* @author Charlotte*/@RestController
@RequestMapping("/piano")
public class PianoController {@Resourceprivate PianoService pianoService;@RequestMapping("/hello")public String hello(){return "Hello World!";}@RequestMapping("/add")public String add(){return "添加成功！";}@RequestMapping("/list")public List<piano> findAll(){return this.pianoService.findAll();}
}