PageLoader(Document doc,InputStream in,URL old,URL page){
  this.in=in;
  this.old=old;
  this.page=page;
  this.doc=doc;
}

PageLoader ( Document doc , InputStream in , URL old , URL page ) { this . in = in ; this . old = old ; this . page = page ; this . doc = doc ; }
construct an asynchronous page loader .
