Spring Boot 3迁移：@Type(ClassType)代码适配问题咨询

问题背景 #

原Spring Boot 2及更早版本代码：

@Column(name = "OPTION_TYPE")
@Type(type = "org.hibernate.type.ClassType")
private Class<T> clazz;

迁移到Spring Boot 3后报错：

Cannot resolve method 'type'

尝试替换为以下代码后出现新错误：

@Column(name = "OPTION_TYPE")
@JdbcTypeCode(SqlTypes.JAVA_OBJECT)
private Class<T> clazz;

错误日志：

Caused by: jakarta.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory; nested exception is org.hibernate.MappingException: Unable to determine SQL type name for column 'option_type' of table 'account_options' because there is no type mapping for org.hibernate.type.SqlTypes code: 2000 (JAVA_OBJECT)
        at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:421) ~[spring-orm-6.1.5.jar!/:6.1.5]
        at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:396) ~[spring-orm-6.1.5.jar!/:6.1.5]
        at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:366) ~[spring-orm-6.1.5.jar!/:6.1.5]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1833) ~[spring-beans-6.1.5.jar!/:6.1.5]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1782) ~[spring-beans-6.1.5.jar!/:6.1.5]
        ... 92 common frames omitted
Caused by: org.hibernate.MappingException: Unable to determine SQL type name for column 'option_type' of table 'account_options' because there is no type mapping for org.hibernate.type.SqlTypes code: 2000 (JAVA_OBJECT)

解决方案 #

方法1：使用Hibernate 6.x原生类型（推荐） #

Spring Boot 3搭配的Hibernate 6.x重构了类型系统，原ClassType替换为ClassJavaType，需明确指定数据库列类型：

import jakarta.persistence.Column;
import org.hibernate.annotations.Type;
import org.hibernate.type.descriptor.java.ClassJavaType;

@Column(name = "OPTION_TYPE", columnDefinition = "VARCHAR(255)")
@Type(ClassJavaType.class)
private Class<T> clazz;

方法2：自定义类型处理类 #

若方法1不生效，可自定义类型处理类实现类型转换：

import org.hibernate.type.AbstractSingleColumnStandardBasicType;
import org.hibernate.type.descriptor.java.ClassJavaType;
import org.hibernate.type.descriptor.jdbc.VarcharJdbcType;

public class ClassType extends AbstractSingleColumnStandardBasicType<Class<?>> {
    public static final ClassType INSTANCE = new ClassType();

    public ClassType() {
        super(VarcharJdbcType.INSTANCE, ClassJavaType.INSTANCE);
    }

    @Override
    public String getName() {
        return "class";
    }
}

实体类中使用：

@Column(name = "OPTION_TYPE", columnDefinition = "VARCHAR(255)")
@Type(ClassType.class)
private Class<T> clazz;

方法3：手动处理类名存储 #

放弃ORM自动转换，直接存储类全限定名字符串，手动实现类型转换：

@Column(name = "OPTION_TYPE", length = 255)
private String className;

// 手动转换方法
public Class<T> getClazz() throws ClassNotFoundException {
    return (Class<T>) Class.forName(className);
}

public void setClazz(Class<T> clazz) {
    this.className = clazz.getName();
}

内容的提问来源于stack exchange，提问作者Peter Penzov