public Map<String, String> buildKeyWordMap(File indexFile) {
		Map<String, String> result = new HashMap<String, String>();
		try {
			BufferedReader reader = new BufferedReader( new InputStreamReader( new FileInputStream(indexFile)));
			String s;
			while((s = reader.readLine()) != null) {
				String[] indexArray = s.split("\t");
				String keyWord = indexArray[0].toLowerCase();
				String index = indexArray[1].replaceFirst(Constants.SPLIT_FLAG, "");
				if (result.containsKey(keyWord)) {
					index = index + Constants.SPLIT_FLAG + result.get(keyWord);
				}
				result.put(keyWord, index);
			}
			reader.close();
			
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		return result;
	}