TypeUtils.java 文件源码

/**
 * Given an input class, finds the usage of 'wanted', and returns the
 * annotated type number of param.
 */

public static AnnotatedType getParamterOfInterface(Class<?> klass, Class<?> wanted, int param) {

  final AnnotatedType val = TypeUtils.getInterfaceType(klass, wanted);

  if (val == null) {
    // no base class implements the given interface
    return null;
  }

  //

  if (!(val instanceof AnnotatedParameterizedType)) {
    throw new IllegalArgumentException("is not a parameterized type");
  }

  final AnnotatedParameterizedType ptype = (AnnotatedParameterizedType) val;

  if (param >= ptype.getAnnotatedActualTypeArguments().length) {
    throw new IllegalArgumentException("too many");
  }

  return ptype.getAnnotatedActualTypeArguments()[param];

}