import com.intellij.ide.actions.QualifiedNameProvider; //导入依赖的package包/类
@Nullable
public static String getQualifiedNameFromProviders(@Nullable com.intellij.psi.PsiElement element) {
  if (element == null) return null;
  for (QualifiedNameProvider provider : Extensions.getExtensions(QualifiedNameProvider.EP_NAME)) {
    String result = provider.getQualifiedName(element);
    if (result != null) return result;
  }
  return null;
}
 

import com.intellij.ide.actions.QualifiedNameProvider; //导入依赖的package包/类
@Nullable
public static Pair<PsiElement, QualifiedNameProvider> findElementByQualifiedName(@Nullable String qName, @Nonnull Project project) {
  QualifiedNameProvider theProvider = null;
  PsiElement element = null;
  for(QualifiedNameProvider provider: QualifiedNameProvider.EP_NAME.getExtensions()) {
    element = provider.qualifiedNameToElement(qName, project);
    if (element != null) {
      theProvider = provider;
      break;
    }
  }
  return theProvider == null ? null : Pair.create(element, theProvider);
}
 

import com.intellij.ide.actions.QualifiedNameProvider; //导入依赖的package包/类
@NotNull
@Override
protected String getLookupString(@NotNull Object item) {
  if (item instanceof PsiElement) {
    for (QualifiedNameProvider provider : Extensions.getExtensions(QualifiedNameProvider.EP_NAME)) {
      String result = provider.getQualifiedName((PsiElement)item);
      if (result != null) {
        return result;
      }
    }
  }
  return item.toString();
}