JPA双向多对多关联关系@ManyToMany

短命女 2022-05-20 08:23 229阅读 0赞

package com.jpa.helloworld;
    
    import java.util.HashSet;
    import java.util.Set;
    
    import javax.persistence.Column;
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.Id;
    import javax.persistence.JoinColumn;
    import javax.persistence.JoinTable;
    import javax.persistence.ManyToMany;
    import javax.persistence.Table;
    
    @Table(name="ITEMS")
    @Entity
    public class Item {
    
    	private Integer iId;
    
    	private String iName;
    
    	private Set<Category> categorys = new HashSet<Category>();
    
    	@Id
    	@GeneratedValue
    	@Column(name="I_ID")
    	public Integer getiId() {
    		return iId;
    	}
    
    	public void setiId(Integer iId) {
    		this.iId = iId;
    	}
    
    	@Column(name="I_NAME")
    	public String getiName() {
    		return iName;
    	}
    
    	public void setiName(String iName) {
    		this.iName = iName;
    	}
    
    	//使用@JoinTable注解添加中间表
    	//其中name属性设置中间表的表名
    	//joinCloums属性在中间表中添加的列
    	//JoinColumns属性：
    	//				@joinColumn属性设置中间表中的列名
    	//						referencedColumnName属性指向被映射表的主键（可以没有该属性）
    	//@inverseJoinColumns另外一张表在中间表中的列
    	@JoinTable(
    			name="ITEMS_CATEGORYS",
    //			joinColumns = {@JoinColumn(name="ITEM_ID",referencedColumnName="I_ID")},
    			joinColumns = {@JoinColumn(name="ITEM_ID")},
    //			inverseJoinColumns= {@JoinColumn(name="CATEGORY_ID", referencedColumnName="C_ID")})
    			inverseJoinColumns= {@JoinColumn(name="CATEGORY_ID")})
    	@ManyToMany
    	public Set<Category> getCategorys() {
    		return categorys;
    	}
    
    	public void setCategorys(Set<Category> categorys) {
    		this.categorys = categorys;
    	}
    
    }