将List<Map>中的datas转换为json格式写入文件

private static boolean writeToTextFileByJson(List<Map<String, Object>> datas, String title, String columns,
			String fileName, String encode) {
		final BufferedWriter bw;
		boolean flag = true;
		try {
			boolean hasExists = new File(fileName).exists();
			if(!hasExists){
			createLocDir(fileName);//创建目录
			}
			File f = new File(fileName);
			bw = new BufferedWriter(new FileWriter(f, false));
			final String[] allcolumns = columns.substring(0, columns.length()).split(",");
			Map<String, Object> resultMap = new HashMap<String, Object>();
			String mobile = "";
			List<Map<String,Object>> columnList = new ArrayList<Map<String,Object>>();
			
			//mobileMap.put("mobile", (String) m.get(allcolumns[0].toUpperCase()));
					Object value ="";
					for(Map<String, Object> map : datas) {
						for (int i = 1; i < allcolumns.length; i++) {
							String columnName = allcolumns[i];
						Set<String> set = map.keySet();
						if(set.contains(columnName)){
							value =  map.get(columnName);
						}
						mobile = (String) map.get(allcolumns[0].toUpperCase());
						resultMap.put("mobile", mobile);
						HashMap<String, Object> columnMap = new HashMap<String, Object>();
						columnMap.put("colum_name", columnName); 
						columnMap.put("value", value);
						columnList.add(columnMap);
					resultMap.put("column", columnList);
					String json = JsonUtil.toJson(resultMap).toString();
					bw.write(json);
					columnList.clear();
					}
			}
			
			if (bw != null) {
				bw.close();
			}
		} catch (Exception e) {
			flag = false;
			LOG.error("createFile(" + fileName + ") error:", e);
			e.printStackTrace();
		} 
		return flag;
	}