项目结构

 一、添加Spring Data JPA依赖启动器

 另外,添加MySQL数据库依赖

       <!--spring data jpa依赖启动器-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <!--MySql依赖-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.13</version>
        </dependency>

二、编写ORM实体类

 

package com.uos.jpa.entity;

import javax.persistence.*;

@Entity(name = "t_comment")
public class Discuss {
    @Id     //表明映射对应的主键id
    @GeneratedValue(strategy = GenerationType.IDENTITY) //设置主键自增策略
    private Integer id;
    private String content;
    private String author;
    @Column(name = "a_id")  //指定映射的表字段名
    private Integer aId;

    @Override
    public String toString() {
        return "Discuss{" +
                "id=" + id +
                ", content='" + content + '\'' +
                ", author='" + author + '\'' +
                ", aId=" + aId +
                '}';
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public Integer getaId() {
        return aId;
    }

    public void setaId(Integer aId) {
        this.aId = aId;
    }
}

Discuss

三、编写Repository接口

 

package com.uos.jpa.repository;
import com.uos.jpa.entity.Discuss;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Modifying;
import org.springframework.data.jpa.repository.Query;
import javax.transaction.Transactional;
import java.awt.print.Pageable;
import java.util.List;

public interface DiscussRepository extends JpaRepository<Discuss,Integer> {
    // 1.查询author非空的Discuss评论集合
    public List<Discuss> findByAuthorNotNull();
    // 2.根据文章id分页查询Discuss评论集合
    @Query("SELECT c FROM t_comment c WHERE  c.aId = ?1")
    public List<Discuss> getDiscussPaged(Integer aid, Pageable pageable);
    // 3.使用元素SQL语句,根据文章id分页查询Discuss评论集合
    @Query(value = "SELECT * FROM t_comment  WHERE  a_Id = ?1",nativeQuery = true)
    public List<Discuss> getDiscussPaged2(Integer aid,Pageable pageable);
    // 4.根据评论id修改评论作者author
    @Transactional
    @Modifying
    @Query("UPDATE t_comment c SET c.author = ?1 WHERE  c.id = ?2")
    public int updateDiscuss(String author,Integer id);
    // 5.根据评论id删除评论
    @Transactional
    @Modifying
    @Query("DELETE t_comment c WHERE  c.id = ?1")
    public int deleteDiscuss(Integer id);
}

DiscussRepository

四、全局文件配置application.properties

 

spring.datasource.url=jdbc:mysql://192.168.152.120:3306/springbootdata?serverTimezone=UTC
spring.datasource.username=root
spring.datasource.password=1

application.properties

五、编写单元测试进行接口方法测试

package com.uos.jpa;

import com.uos.jpa.entity.Discuss;
import com.uos.jpa.repository.DiscussRepository;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;


@SpringBootTest
class JpaApplicationTests {

    @Autowired
    private DiscussRepository repository;

    @Test
    public void selectCommentByKeys() {
        List<Discuss> list = repository.findByAuthorNotNull();
        System.out.println(list); }

    @Test
    void contextLoads() {
    }

}

JpaApplicationTests

运行结果

使用debug模式调试

 

 

12-14 17:07
查看更多