Hibernate 自定义 SQL 枚举转换失败

Question

这里有类似的问题，但没有一个对我有用。我有一个自定义 SQL，它返回 2 列：一个字符串，一个数字。并且字符串列始终是一个完整的大写 ENUM 名称。我想将此结果集提供给具有上述枚举的自定义 bean。

按照 Hibernate 5.X 的答案 here，代码如下

    Properties params = new Properties();
    params.put("enumClass", "MyEnumClass");
    params.put("useNamed", true);
    Type myEnumType = new TypeLocatorImpl(new TypeResolver()).custom(MyEnumClass.class, params);

    final Query query = getCurrentSession().createSQLQuery(MY_CUSTOM_SQL)
            .addScalar("col1", myEnumType)
            .addScalar("col2", StandardBasicTypes.INTEGER)
            .setLong("someSqlVar", someVal)
            .setResultTransformer(Transformers.aliasToBean(MyCustomBean.class));

    return query.list();

这段代码甚至没有执行 query.list() 方法，它在这一行失败：

Type myEnumType = new TypeLocatorImpl(new TypeResolver()).custom(MyEnumClass.class, params);

异常跟踪：

Caused by: org.hibernate.MappingException: Unable to instantiate custom type: com.example.MyEnumClass
...
Caused by: java.lang.InstantiationException: com.example.MyEnumClass
...
Caused by: java.lang.NoSuchMethodException: com.example.MyEnumClass.<init>()
at java.lang.Class.getConstructor0(Class.java:3082) ~[?:1.8.0_60]
at java.lang.Class.newInstance(Class.java:412) ~[?:1.8.0_60]
at org.hibernate.type.TypeFactory.custom(TypeFactory.java:202) ~[hibernate-core-5.1.0.Final.jar:5.1.0.Final]
at org.hibernate.type.TypeFactory.custom(TypeFactory.java:193) ~[hibernate-core-5.1.0.Final.jar:5.1.0.Final]
at org.hibernate.internal.TypeLocatorImpl.custom(TypeLocatorImpl.java:144) ~[hibernate-core-5.1.0.Final.jar:5.1.0.Final]
...

所以休眠尝试调用MyEnumClass.class.newInstance() 并失败。它甚至不检查我通过的属性。使用 Hibernate 5.1.0.Final，我不应该这样使用自定义类型吗？

Answer 1

我找到了一种方法：

Properties params = new Properties();
params.put("enumClass", MyEnumClass.class.getName());
params.put("useNamed", true);

EnumType enumType = new EnumType();
enumType.setParameterValues(params);
CustomType customType = new CustomType(enumType);

final Query query = getCurrentSession().createSQLQuery(MY_CUSTOM_SQL)
   .addScalar("col1", customType)
   .addScalar("col2", StandardBasicTypes.INTEGER)
   .setLong("someSqlVar", someVal)
   .setResultTransformer(Transformers.aliasToBean(MyCustomBean.class));

return query.list();