java泛型问题，急救

Question

import java.io.IOException;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.type.TypeReference;

public class JsonReader<T> {

public static <T> T readValue(String json) {
	ObjectMapper mapper = new ObjectMapper();
	try {
		TypeReference<T> ref = new TypeReference<T>() {};
		System.out.println(ref.getClass());
		System.out.println(ref.getType());
		return mapper.readValue(json, ref);
	} catch (JsonParseException e) {
		e.printStackTrace();
	} catch (JsonMappingException e) {
		e.printStackTrace();
	} catch (IOException e) {
		e.printStackTrace();
	}
}
}
请问这里哪里错了，TypeReference<T>得不到T的具体类型

Answer 1

ParameterizedType type = (ParameterizedType) this.getClass().getGenericSuperclass();
Type[] types = type.getActualTypeArguments();
Class<T> subClass = (Class<T>) types[0];

Answer 2

Class<T> subClass = (Class<T>) ((ParameterizedType) (this.getClass().getGenericSuperclass())).getActualTypeArguments()[0];