ant delete

The * wildcard should only delete the files at the top level

------------- 

<delete>
   <fileset dir="${dist.dir}">
      <include name="*"/>
   </fileset>
</delete>

 -------------

the subdirectories will be deleted,you'd need to use **/* instead. 

<delete includeEmptyDirs="true">
  <fileset dir="dir_name" includes="**/*" defaultexcludes="no"/>
</delete>