code: @SuppressWarnings("unchecked")
      public static <T> Class<T> loadClass(String className, ClassLoader loader) {
          Assert.notNull(className, "className不能为null");
          Assert.notNull(loader, "loader不能为null");
          switch (className) {
              case "boolean":
                  return (Class<T>) boolean.class;
              case "byte":
                  return (Class<T>) byte.class;
              case "char":
                  return (Class<T>) char.class;
              case "short":
                  return (Class<T>) short.class;
              case "int":
                  return (Class<T>) int.class;
              case "long":
                  return (Class<T>) long.class;
              case "double":
                  return (Class<T>) double.class;
              case "float":
                  return (Class<T>) float.class;
              default:
                  try {
                      return (Class<T>) loader.loadClass(className);
                  } catch (ClassNotFoundException e) {
                      throw new ReflectException("找不到指定class：" + className, e);
                  }
          }
      }
docs: 使用指定ClassLoader加载class
  
  @param className class名字
  @param loader    加载class的ClassLoader
  @param <T>       class实际类型
  @return class