public boolean delete(String filename) {
		if (true ==  namenode.exits(filename)) {
			List<String>  chunk_uuids = (List<String> ) namenode.filetable.get(filename);
			for (Object chunk_uuid : chunk_uuids) {
				int chunkloc = (Integer) namenode.chunktable.get(chunk_uuid);
				((DataNode)namenode.datanodes.get(chunkloc)).delete(chunk_uuid.toString()); //#ɾ:һ
				((DataNode)namenode.datanodes.get(chunkloc%namenode.num_datanodes + 1)).delete(chunk_uuid.toString());//#ɾڶ
			}
			namenode.delete(filename); //߼ɾԪɾϢ
			return true;
		}
		else{
			return false;
		}
	}