SpringBoot实战教程（7）| 整合JPA

JPA是Java Persistence API的简称，中文名Java持久层API，是JDK 5.0注解或XML描述对象－关系表的映射关系，并将运行期的实体​​对象持久化​​到数据库中。

目录

​​一、初始化springboot项目​​

​​二、引入依赖文件​​

​​三、编写配置文件​​

​​四、编写测试案例​​

​​User.java​​

​​ UserDao.java​​

​​UserService.java​​

​​UserServiceimpl.java​​

​​ JpaController.java​​

​​五、运行结果展示​​

---

一、初始化springboot项目

二、引入依赖文件

<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.27</version>
</dependency>

<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>
<version>2.6.1</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>

三、编写配置文件

注意：需要提前建立好数据库，表可以不建。

#通用数据源配置
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/springboot_jpa?charset=utf8mb4&useSSL=false
spring.datasource.username=root
spring.datasource.password=123456
# Hikari 数据源专用配置
spring.datasource.hikari.maximum-pool-size=20
spring.datasource.hikari.minimum-idle=5
# JPA 相关配置
spring.jpa.database-platform=org.hibernate.dialect.MySQL5InnoDBDialect
spring.jpa.show-sql=true
spring.jpa.hibernate.ddl-auto=create

四、编写测试案例

User.java

package com.csdn.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import javax.persistence.*;

@Entity
@Table(name = "AUTH_USER") //表名
@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
@Id //主键ID
@GeneratedValue(strategy = GenerationType.IDENTITY) //主键自增
private Long id;

@Column(length = 32) //字段最大允许长度
private String username;

@Column(length = 32)
private String password;

}

 UserDao.java

package com.csdn.dao;

import com.csdn.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface UserDao extends JpaRepository<User, Long> {
}

UserService.java

package com.csdn.service;

import com.csdn.entity.User;

import java.util.List;

public interface UserService {

public List<User> users();

}

UserServiceimpl.java

package com.csdn.service.impl;

import com.csdn.dao.UserDao;
import com.csdn.entity.User;
import com.csdn.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class UserServiceimpl implements UserService {

@Autowired
private UserDao userDao;

@Override
public List<User> users() {
User user1 = new User(1L, "admin1", "123456");
User user2 = new User(2L, "admin2", "123456");
userDao.save(user1);
userDao.save(user2);
List<User> users = userDao.findAll();
return users;
}
}

 JpaController.java

package com.csdn.controller;

import com.csdn.entity.User;
import com.csdn.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
public class JpaController {

@Autowired
private UserService userService;

@GetMapping("/users")
public List<User> users() {
return userService.users();
}

}

五、运行结果展示

我们在启动日志中可以看到数据库的创建过程。

 

 然后我们访问：localhost:8080/users

到这里，一个简单的整合过程就完成了。如果本篇文章对你有帮助，请一键三连支持，谢谢。