spring - 使用 @Converter 为泛型类实现 AttributeConverter

Question

如何实现泛型的 AttributeConverter？

类似的东西

class JSONConverter<T> implements AtttributeConverter<T,String>{
   //Here How do I get the generic class type with which I can convert a serialized object
}

在实体类中调用转换器

@Column
@Convert( converter = JSONConverter.class) //How do I pass the Generic here
private SomeClass sm;

Answer 1

可以做得更简单，因为您不一定需要通过构造函数传递 typeReference:

public abstract class JsonConverter<T> implements AttributeConverter<T, String> {

    private final TypeReference<T> typeReference = new TypeReference<T>() {};

    @Resource
    private ObjectMapper objectMapper;

    @Override
    public String convertToDatabaseColumn(T object) {
        try {
            return objectMapper.writeValueAsString(object);
        } catch (JsonProcessingException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public T convertToEntityAttribute(String json) {
        try {
            return objectMapper.readValue(json, typeReference);
        } catch (JsonProcessingException e) {
            throw new RuntimeException(e);
        }
    }
}

然后是类，扩展你的 JsonConventer 看起来像:

public class SomeClassConverter extends JsonConverter<SomeClass> { }