受限类型参数( 推论变量T具有不兼容的上限)

public class EnumUtil {

    public static <T extends CodeEnum> T getByCode(Integer code, Class<T> enumClass) {
        for (T each: enumClass.getEnumConstants()) {
            if (code.equals(each.getCode())) {
                return each;
            }
        }
        return null;
    }
T必须是CodeEnum接口的实现.