import org.eclipse.jdt.core.ITypeHierarchyChangedListener; //导入依赖的package包/类
private ITypeHierarchy getSupertypes(final IType type) throws JavaModelException
{
	ITypeHierarchy hierarchy = cache.get(type);
	if (hierarchy == null || !hierarchy.exists())
	{
		hierarchy = type.newSupertypeHierarchy(new NullProgressMonitor());
		hierarchy.addTypeHierarchyChangedListener(new ITypeHierarchyChangedListener()
		{
			@Override
			public void typeHierarchyChanged(ITypeHierarchy typeHierarchy)
			{
				cache.remove(type);
			}
		});
		cache.put(type, hierarchy);
	}
	return hierarchy;
}