Question

我有一个父类，它是一个访客类，它将包含访问者的所有字段。课程如下。

package classes.trantables;

import java.io.Serializable;
import java.sql.Time;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.Lob;
import javax.persistence.Table;

import java.sql.Date;

import org.hibernate.annotations.GenericGenerator;
import org.hibernate.annotations.Type;


@Entity
@Table(name="VISITORS")
@Inheritance(strategy=InheritanceType.TABLE_PER_CLASS)
public class Visitors implements  Serializable{
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    @Id
    @Column(nullable=false,name="COMPANY_ID")
    private String companyId;//Maps to company 
    @Id
    @Column(nullable=false,name="BRANCH_ID")
    private String branchId;//number of branches
    /* (non-Javadoc)
     * @see java.lang.Object#hashCode()
     */
    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result
                + ((branchId == null) ? 0 : branchId.hashCode());
        result = prime * result
                + ((companyId == null) ? 0 : companyId.hashCode());
        result = prime * result + ((passNo == null) ? 0 : passNo.hashCode());
        return result;
    }
    /* (non-Javadoc)
     * @see java.lang.Object#equals(java.lang.Object)
     */
    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (!(obj instanceof Visitors)) {
            return false;
        }
        Visitors other = (Visitors) obj;
        if (branchId == null) {
            if (other.branchId != null) {
                return false;
            }
        } else if (!branchId.equals(other.branchId)) {
            return false;
        }
        if (companyId == null) {
            if (other.companyId != null) {
                return false;
            }
        } else if (!companyId.equals(other.companyId)) {
            return false;
        }
        if (passNo == null) {
            if (other.passNo != null) {
                return false;
            }
        } else if (!passNo.equals(other.passNo)) {
            return false;
        }
        return true;
    }
    @Id
    @Column(nullable=false,name="PASS_NO")
    private String passNo;//Random generated
    @Column(nullable=false)
    private String visitorName;//Name given by the visitor
    //remainder of the class is not required..

现在我想创建一个类，它是这个类的子类，它存储访问者的所有所有物。我希望来自VISITOR类的COMPANY_ID，BRANCH_ID，PASS_NO和来自Belongings类的ItemName成为Belongings类的主键。我想要每个子类一个表，但如果我将上面的类放在映射中，我会收到错误。

这就是我在下面试过的..

package classes.trantables;

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.PrimaryKeyJoinColumn;
import javax.persistence.PrimaryKeyJoinColumns;
import javax.persistence.Table;

@Entity
@Table(name="BELONGINGS")
@PrimaryKeyJoinColumns({@PrimaryKeyJoinColumn(name="COMPANY_ID",referencedColumnName="COMPANY_ID"),
    @PrimaryKeyJoinColumn(name="BRANCH_ID",referencedColumnName="BRANCH_ID"),
    @PrimaryKeyJoinColumn(name="PASS_NO", referencedColumnName="PASS_NO")
})


public class Belongings extends Visitors{
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    @Id
    private String itemNm;
    private String model;
    private String srNo;

Answer 1

您的子类中不应该有另一个@Id带注释的属性。从@Id中itemNm移除Belongings将取消此例外。

org.hibernate.mapping.UnionSubclass无法强制转换为org.hibernate.mapping.RootClass

1 个答案: