Hibernate 多对一查询，以及一对多关联删除

来源：互联网发布：windows系统启动 efi 编辑：程序博客网时间：2024/06/03 14:53

类别、标签（一个类别，有多个标签）

一对多关联删除（在一的这边进行如下配置就可以了）

在删除“一”的这一方的数据时，“多”的这一方的相关数据也会被删除；

@OneToMany(mappedBy="articleCategory",fetch=FetchType.EAGER,cascade=CascadeType.REMOVE)private Set<ArticleTags> articleTags;  //标签

类别完整的实体类代码：

package com.wamei.entity;import org.hibernate.annotations.GenericGenerator;import javax.persistence.*;import java.io.Serializable;import java.util.Set;/** * APP版本表 * @author chain * 文章类别 */@Entity@Table(name="T_ARTICLE_CATEGORY")public class ArticleCategory implements Serializable {/** * */private static final long serialVersionUID = 1L;@Id@GeneratedValue(generator = "paymentableGenerator")@GenericGenerator(name = "paymentableGenerator", strategy = "uuid")@Column(name = "ID")private String id;@Column(name = "NAME")private String name;@OneToMany(mappedBy="articleCategory",fetch=FetchType.EAGER,cascade=CascadeType.REMOVE)private Set<ArticleTags> articleTags;//标签public String getId() {return id;}@Column(name = "ORDER_INDEX")private int orderIndex;public void setId(String id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public static long getSerialVersionUID() {return serialVersionUID;}public int getOrderIndex() {return orderIndex;}public void setOrderIndex(int orderIndex) {this.orderIndex = orderIndex;}public Set<ArticleTags> getArticleTags() {return articleTags;}public void setArticleTags(Set<ArticleTags> articleTags) {this.articleTags = articleTags;}}

多对一的查询（在查询“多” 的这一方时，把“一”的这一方的相关数据也查询出来）

在“多”的一方的实体类进行如下配置

@ManyToOne@JoinColumn(name = "CATEGOTY_ID")private ArticleCategory articleCategory;

获取“一”这一方的相关字段的属性设置如下

@Transientpublic String getCategoryName(){   String str = "";   try {      str = null==this.articleCategory?"无":articleCategory.getName();   } catch (Exception e) {      str = "无";   }   return str;}

注意：在添加多的一方数据时，前端页面的属性名称写法如下

articleCategory是“多”的一方的属性对象

所以类别的ID的属性的写法应该是：articleCategory.id (这里的id对应的是类别的属性)

<div class="field-box"><label>类别:</label><div class="ui-select"><select style="height: 32px;" id="categoryId" name="articleCategory.id"><option value="">--请选择--</option><c:forEach items="${cataList}" var="item" varStatus="status"><option value="${item.id}">${item.name}</option></c:forEach></select></div></div>

标签实体类：

package com.wamei.entity;import org.hibernate.annotations.GenericGenerator;import javax.persistence.*;import java.io.Serializable;/** * APP版本表 * @author chain * 文章标签 */@Entity@Table(name="T_ARTICLE_TAGS")public class ArticleTags implements Serializable {/** * */private static final long serialVersionUID = 1L;@Id@GeneratedValue(generator = "paymentableGenerator")@GenericGenerator(name = "paymentableGenerator", strategy = "uuid")@Column(name = "ID")private String id;@Column(name = "NAME")private String name;@Column(name = "ORDER_INDEX")private int orderIndex;@ManyToOne@JoinColumn(name = "CATEGOTY_ID")private ArticleCategory articleCategory;public String getId() {return id;}public void setId(String id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getOrderIndex() {return orderIndex;}public void setOrderIndex(int orderIndex) {this.orderIndex = orderIndex;}public static long getSerialVersionUID() {return serialVersionUID;}public ArticleCategory getArticleCategory() {return articleCategory;}public void setArticleCategory(ArticleCategory articleCategory) {this.articleCategory = articleCategory;}@Transientpublic String getCategoryName(){String str = "";try {str = null==this.articleCategory?"无":articleCategory.getName();} catch (Exception e) {str = "无";}return str;}}

0 0