当hibernate必须是表的主键时，如何使用休眠生成自定义ID

Z时代
2024-01-10
分类：问答

这是我的pojo课

@Entity
public class Department {
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="Department_Id")
private Integer deptId;
@Column(name="Department_Name",unique=true,nullable=false)
private String deptName;
@Column(name="Department_Description")
@NotNull
private String deptDesc;
   //geters and setters

我想要的是department_id必须是此Department表的主键，并且该键的条目必须为DEP0001，DEP0002，DEP0003

回答：

谢谢大家的回答……最后，我在Department类中做了一些更改，并使用了一个类来生成IDs ....这是我的代码

@Entity
public class Department {
@Id
@GenericGenerator(name = "sequence_dep_id", strategy = "com.xyz.ids.DepartmentIdGenerator")
@GeneratedValue(generator = "sequence_dep_id")  
@Column(name="Department_Id")
private String deptId;
@Column(name="Department_Name",unique=true,nullable=false)
private String deptName;
@Column(name="Department_Description")
@NotNull
private String deptDesc;
//getters and setters

DepartmentIdGenerator.java

package com.xyz.ids;
import java.io.Serializable;
import java.sql.*;
import org.hibernate.HibernateException;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.id.IdentifierGenerator;
public class DepartmentIdGenerator implements IdentifierGenerator{
    @Override
    public Serializable generate(SessionImplementor session, Object object)
            throws HibernateException {
        String prefix = "DEP";
        Connection connection = session.connection();
        try {
            Statement statement=connection.createStatement();
            ResultSet rs=statement.executeQuery("select count(Department_Id) as Id from demo.Department");
            if(rs.next())
            {
                int id=rs.getInt(1)+101;
                String generatedId = prefix + new Integer(id).toString();
                System.out.println("Generated Id: " + generatedId);
                return generatedId;
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }
}