package com.example.demo.entity;import javax.persistence.*;/*使用jpa注解配置映射关系*//*告诉jpa这是一个实体类和（数据表映射的类）*/@Entity@Table(name = "tal_user")public class User {    @Id /*这是主键*/    @GeneratedValue(strategy = GenerationType.IDENTITY) /*主键自增*/    private Integer id;    @Column(name = "lastName",length = 50)/*这是和数据表对应的一个列*/    private String lastName;    @Column  /*省略就代表默认属性名就是列名*/    private String email;    public Integer getId() {        return id;    }    public void setId(Integer id) {        this.id = id;    }    public String getLastName() {        return lastName;    }    public void setLastName(String lastName) {        this.lastName = lastName;    }    public String getEmail() {        return email;    }    public void setEmail(String email) {        this.email = email;    }}

package com.example.demo.repository;import com.example.demo.entity.User;import org.springframework.data.jpa.repository.JpaRepository;/*继承jpaRepository来完成对数据库的操作 参数是实体类型和实体类中的Id类型*/public interface UserRepository extends JpaRepository
     
       {}
     

package com.example.demo.Controller;import com.example.demo.entity.User;import com.example.demo.repository.UserRepository;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.RestController;import java.util.List;@RestControllerpublic class UserController {    @Autowired    UserRepository userRepository;    @GetMapping("/user/{id}")    public List
     
       getUser(@PathVariable("id") Integer id){        User user = userRepository.getOne(id);        final List
      
        users = userRepository.findAll();        return users;    }    @GetMapping("/user")    public User insertUser(User user){        User save = userRepository.save(user);        return save;    }}
      
     

spring:  datasource:    username: root    password: root    url: jdbc:mysql://localhost:3306/jpa?serverTimezone=UTC    driver-class-name: com.mysql.cj.jdbc.Driver  jpa:    hibernate:#      更新或者创建表结构      ddl-auto: update#      控制台显示sql    show-sql: true

 

                 
      
       mysql
                  
      
       mysql-connector-java
                  
      
       8.0.12