SpringBoot整合SpringData JPA详解

本篇文章主要记录SpringBoot整合SpringData JPA，感兴趣的小伙伴和小编一起来学习吧！

1、添加依赖

<parent>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-parent</artifactId>
	<version>2.4.4</version>
	<relativePath/>
</parent>
<dependencies>
	<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>
	</dependency>
	<dependency>
		<groupId>mysql</groupId>
		<artifactId>mysql-connector-java</artifactId>
		<scope>runtime</scope>
	</dependency>
</dependencies>

2、编写一个实体类

编写一个实体类（bean）和数据表进行映射，并且配置好映射关系；

import javax.persistence.*;

//使用JPA注解配置映射关系
@Entity //告诉JPA这是一个实体类（和数据表映射的类）
@Table(name = "tbl_user") //@Table来指定和哪个数据表对应;如果省略默认表名就是user；
public class User {
    
    

    @Id //这是一个主键
    @GeneratedValue(strategy = GenerationType.IDENTITY)//自增主键
    private Integer id;

    @Column(name = "last_name",length = 50) //这是和数据表对应的一个列
    private String lastName;
    @Column //省略默认列名就是属性名
    private String email;
}

3、编写一个Dao接口来操作实体类对应的数据表

//继承JpaRepository来完成对数据库的操作
public interface UserRepository extends JpaRepository<User,Integer> {
    
    
}

4、application配置

spring:
  datasource:
    url: jdbc:mysql://192.168.0.104/jpa
    username: root
    password: 123456
    driver-class-name: com.mysql.jdbc.Driver
  jpa:
    hibernate:
#     更新或者创建数据表结构
      ddl-auto: update
#    控制台显示SQL
    show-sql: true

5、编写接口

import com.gzl.cn.entity.User;
import com.gzl.cn.repository.UserRepository;

import java.util.Optional;

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;

@RestController
public class UserController {
    
    

    @Autowired
    UserRepository userRepository;

    @GetMapping("/user/{
    
    id}")
    public User getUser(@PathVariable("id") Integer id){
    
    
        Optional<User> optional = userRepository.findById(id);
        if (optional.isPresent()) {
    
    
        	User user = optional.get();
            return user;
		}
        return null;
    }

    @GetMapping("/user")
    public User insertUser(User user){
    
    
        User save = userRepository.save(user);
        return save;
    }

}