java - Morphia 映射泛型

Question

为了模拟我看到的行为，我编写了这个测试(给出了完全相同的错误):

@Test
public void testListGenerics() {

    @Entity
    class BaseOne<T> {
        @Id
        ObjectId _id;
        T value;
        void setValue(T value) {
            this.value = value;
        }
    }

    class ListBase<ITEM> extends BaseOne<List<ITEM>> { }

    class ConcreteOne extends ListBase<String> {}

    ConcreteOne concreteOne = new ConcreteOne();
    List<String> strings = Arrays.asList("Hello, ", "world");
    concreteOne.setValue(strings);
    morphia.toDBObject(concreteOne);

}

尝试映射时，我得到:

java.lang.NullPointerException at com.google.code.morphia.utils.ReflectionUtils.getParameterizedClass(ReflectionUtils.java:306) at com.google.code.morphia.utils.ReflectionUtils.getParameterizedClass(ReflectionUtils.java:302) at com.google.code.morphia.utils.ReflectionUtils.getParameterizedClass(ReflectionUtils.java:324) at com.google.code.morphia.utils.ReflectionUtils.getParameterizedClass(ReflectionUtils.java:302) at com.google.code.morphia.utils.ReflectionUtils.getParameterizedType(ReflectionUtils.java:281) at com.google.code.morphia.mapping.MappedField.discoverMultivalued(MappedField.java:136) at com.google.code.morphia.mapping.MappedField.discover(MappedField.java:96) at com.google.code.morphia.mapping.MappedField.(MappedField.java:76) at com.google.code.morphia.mapping.MappedClass.discover(MappedClass.java:197) at com.google.code.morphia.mapping.MappedClass.(MappedClass.java:119) at com.google.code.morphia.mapping.Mapper.getMappedClass(Mapper.java:225) at com.google.code.morphia.DatastoreImpl.getWriteConcern(DatastoreImpl.java:1346) at com.google.code.morphia.DatastoreImpl.save(DatastoreImpl.java:934)

我该怎么做才能使这项工作成功？

Answer 1

你应该在 github 上提交一个问题，我会进行更深入的研究。