如何使用 hibernate 生成自定义 ID 而它必须是表的主键

问题描述

这是我的 pojo 课

Here is my pojo class

@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 必须是这个 Department 表的主键，并且这个键的条目必须是 DEP0001、DEP0002、DEP0003

What i want is that department_id must be primary key of this Department table and entries for this key must be as DEP0001, DEP0002,DEP0003

推荐答案

谢谢大家的回复......最后我在我的 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

Thank you everyone for your response......finally i have done some changes in my Department class and used a class for generating ids........Here is my code

@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

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;
    }

}

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