1.pom.xml文件中添加依赖
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>com.mysql</groupId>
<artifactId>mysql-connector-j</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-test</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
</dependency>2.创建entity文件，用于创建用户类（User）
3.entity文件夹下创建用户类
User代码如下：
package com.example.demo.entity;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name = "tb_user")
public class User {
@Id
@Column(name = "f_id")
private Integer id;
@Column(name = "f_username", unique = true, nullable = false, length = 16)
private String username;
@Column(name = "f_password", length = 32, nullable = false)
private String password;
@Column(name = "f_name", length = 64)
private String name;
@Column(name = "f_age")
private Integer age;
@Column(name = "f_phone", length = 11)
private String phone;
}
4.resources文件夹下创建application.yml文件
配置数据库连接信息 （一定要保证username、password与自己所使用数据库信息一致）
application.yml文件下代码：
sever:
port: 8080
spring:
datasource:
driver-class-name: com.mysql.cj.jdbc.Driver
url: jdbc:mysql://localhost:3306/db_qfnu_test1
username: root
password: 123456
jpa:
hibernate:
ddl-auto: update
show-sql: true
-
Server 配置：
server: port: 8080这部分配置指定了应用程序的服务器配置，该应用程序将在本地监听8080端口。
-
Spring 数据源配置：
spring: datasource: driver-class-name: com.mysql.cj.jdbc.Driver url: jdbc:mysql://localhost:3306/db_qfnu_test username: root password: 123456这一部分配置了Spring框架中的数据源，用于连接数据库。
driver-class-name: 指定数据库驱动类，这里是MySQL的JDBC驱动。url: 数据库连接的URL，包括数据库类型、主机名、端口号和数据库名称。username和password: 数据库连接的用户名和密码。
-
Spring JPA 配置：
spring: jpa: hibernate: ddl-auto: update show-sql: true这一部分配置了Spring Data JPA，用于简化数据访问层的开发。
hibernate.ddl-auto: 指定Hibernate在启动时如何更新数据库表结构。在这里，设置为update表示 Hibernate 将尝试更新数据库表结构，但不会删除表或数据。show-sql: 将此属性设置为true将在控制台上打印出Hibernate执行的SQL语句，方便调试。
5.创建数据库
创建数据库代码：
进入数据库：mysql -u root -p
查看数据库：show databases;
创建新表： create database db_qfnu_test1;
6.运行代码
运行出成功截图：
7.实现对数据库与前端交互
在User类中创建方法
package com.example.demo.entity;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name = "tb_user")
public class User {
@Id
@Column(name = "f_id")
private Integer id;
@Column(name = "f_username", unique = true, nullable = false, length = 16)
private String username;
@Column(name = "f_password", length = 32, nullable = false)
private String password;
@Column(name = "f_name", length = 64)
private String name;
@Column(name = "f_age")
private Integer age;
@Column(name = "f_phone", length = 11)
private String phone;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public void setAge(int age) {
this.age = age;
}
public void setPhone(String phone) {
this.phone = phone;
}
}
创建Dao文件夹，用于创建User接口
Dao文件夹下创建UserDAO接口，选择Interface
UserDAO代码：
package com.example.demo.Dao;
import com.example.demo.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;
public interface UserDAO extends JpaRepository<User, Integer> {
}
创建UserController文件
UserController文件中编写Mapping，代码：
package com.example.demo.controller;
import com.example.demo.Dao.UserDAO;
import com.example.demo.Dao.UserDAO;
import com.example.demo.entity.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.Optional;
@RestController
@RequestMapping("user")
public class UserController {
@Autowired
private final UserDAO userDao;
public UserController(UserDAO userDao){
this.userDao = userDao;
}
@GetMapping("findById/{id}")
public User findById(@PathVariable Integer id){
Optional<User> userOptional = userDao.findById(id);
return userOptional.orElse(null); get or else
}
@PostMapping("add")
public void add(User user){
userDao.save(user);
}
@PostMapping("save")
public String save(@RequestBody User user){
userDao.save(user);
return "success";
}
@PostMapping("removeById/{id}")
public String removeById(@PathVariable Integer id){
userDao.deleteById(id);
return "success";
}
}
数据库中添加表项：
运行代码，导航栏中输入：http://localhost:8080/user/findById/1查看运行结果
前后端交互成功截图：
