如果对 BasicTypeRegistry 中隐式选择 Hibernate type 的结果不满意，也可以通过 @org.hibernate.annotations.Type 显式指定 Hibernate type

org.hibernate.annotations.Type 的 type 属性可以取值：

• org.hibernate.type.Type 实现类的全名
• BasicTypeRegistry 的 key
• type definition(@org.hibernate.annotations.TypeDef) 的 name

package org.example.demo.hibernate;

import javax.persistence.Entity;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Id;
import javax.persistence.Persistence;

public class Test {
    public static void main(String[] args) {
        EntityManagerFactory factory = Persistence.createEntityManagerFactory("test");
        factory.close();
    }

    @Entity(name = "Product")
    public static class Product {
        @Id
        Integer id;
        @org.hibernate.annotations.Type(type = "integer")
        String sku;
    }
}

生成的 SQL

drop table if exists Product cascade

create table Product (id int4 not null, sku int4, primary key (id))

原文档中的例子

package org.example.demo.hibernate;

import javax.persistence.Entity;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Id;
import javax.persistence.Persistence;

public class Test {
    public static void main(String[] args) {
        EntityManagerFactory factory = Persistence.createEntityManagerFactory("test");
        factory.close();
    }

    @Entity(name = "Product")
    public static class Product {
        @Id
        Integer id;
        String sku;
        @org.hibernate.annotations.Type(type = "nstring")
        String name;
        @org.hibernate.annotations.Type(type = "materialized_nclob")
        String description;
    }
}

生成 SQL

drop table if exists Product cascade

create table Product (id int4 not null, description nclob, name nvarchar(255), sku varchar(255), primary key (id))

但是执行 DDL 时出错

• org.postgresql.util.PSQLException: 错误: 类型 "nclob" 不存在
• org.postgresql.util.PSQLException: 错误: 类型 "nvarchar" 不存在