SpringBoot 项目搭建参考
https://blog.csdn.net/zhouzhiwengang/article/details/108402298
源码文件夹（src）定义
实体对象和Dao层
package com.zzg.entity;
import java.util.List;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.experimental.Accessors;
@Entity
@Table(name = "author")
@Data // 自动生成get、set、toString、equals方法
@AllArgsConstructor // 全参构造方法
@NoArgsConstructor // 无参构造方法
@Accessors(chain = true) // 链式编程
public class Author {
@Id // 主键
@GeneratedValue(strategy = GenerationType.IDENTITY) // 自增长策略
private Long id; //id
@Column(nullable = false, length = 20)
private String name;//姓名
//@JoinColumn(name = "author_id")
//级联保存、更新、删除、刷新;延迟加载。当删除用户，会级联删除该用户的所有文章
//拥有mappedBy注解的实体类为关系被维护端
//mappedBy="author"中的author是Article中的author属性
@OneToMany(mappedBy = "author",cascade=CascadeType.ALL,fetch=FetchType.EAGER)
private List<Article> articleList;//文章列表
}
package com.zzg.entity;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import lombok.AllArgsConstructor;
import lombok.EqualsAndHashCode;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;
import lombok.experimental.Accessors;
@Entity
@Table(name = "article")
@Setter
@Getter
@EqualsAndHashCode// 自动生成get、set、toString、equals方法
@AllArgsConstructor // 全参构造方法
@NoArgsConstructor // 无参构造方法
@Accessors(chain = true) // 链式编程
public class Article {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY) // 自增长策略
private Long id;
@Column(nullable = false, length = 50) // 映射为字段，值不能为空
private String title;
@Column(nullable = false) // 映射为字段，值不能为空
private String content;//文章全文内容
//可选属性optional=false,表示author不能为空。删除文章，不影响用户
@ManyToOne(cascade={CascadeType.MERGE,CascadeType.REFRESH},optional=false)
@JoinColumn(name="author_id")//设置在article表中的关联字段(外键)
private Author author;//所属作者
@Override
public String toString() {
// TODO Auto-generated method stub
return "Article{ id='"+id+"'}";
}
}
package com.zzg.dao;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
import com.zzg.entity.Author;
@Repository
public interface AuthorRepository extends JpaRepository<Author, Long> {
Author findByName(String name);
}
package com.zzg.dao;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
import com.zzg.entity.Article;
@Repository
public interface ArticleRepository extends JpaRepository<Article, Long> {
}
功能测试(test)定义:
package com.zzg.test;
import java.util.ArrayList;
import java.util.List;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import com.zzg.dao.ArticleRepository;
import com.zzg.dao.AuthorRepository;
import com.zzg.entity.Article;
import com.zzg.entity.Author;
/**
* spring-data-jpa 一对多测试
* @author zzg
*
*/
@RunWith(SpringRunner.class)
@SpringBootTest
public class OneToMany {
@Autowired
private ArticleRepository articleRepository;
@Autowired
private AuthorRepository authorRepository;
@Test
public void insertOneToMany(){
Author author = new Author();
author.setName("周晨曦");
List<Article> list = new ArrayList<Article>();
for(int i =0; i<10; i++ ){
Article article = new Article();
article.setTitle("标题:" + i);
article.setContent("内容:" + i);
// 记住一定要添加关系实体对象，否在关联字段为null
article.setAuthor(author);
list.add(article);
}
author.setArticleList(list);
authorRepository.save(author);
}
@Test
public void selectOneToMany(){
Author author = authorRepository.findOne(10L);
System.out.println("author=" + author);
}
@Test
public void updateOneToMany(){
Author author = authorRepository.findOne(10L);
List<Article> articleList = author.getArticleList();
Article article = new Article();
article.setAuthor(author);
articleList.add(article);
authorRepository.save(author);
}
@Test
public void deleteOneToMany(){
authorRepository.delete(10L);
}
}
增删改查效果截图：
新增:
查询:
修改:
删除:
涉及表的数据库脚本:
CREATE TABLE `article` (
`id` bigint(20) NOT NULL AUTO_INCREMENT,
`title` varchar(64) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
`content` varchar(64) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
`author_id` bigint(20) NULL DEFAULT NULL,
PRIMARY KEY (`id`) USING BTREE,
INDEX `author_id`(`author_id`) USING BTREE,
CONSTRAINT `author_id` FOREIGN KEY (`author_id`) REFERENCES `author` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;
CREATE TABLE `author` (
`id` bigint(20) NOT NULL AUTO_INCREMENT,
`name` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;
