/** 测试主索引是否存在该文件及获得MD5* */
 public YandeCG testGetIndexByID(String _id) {
   YandeCG yanedCG = new YandeCG();
   yanedCG.setMd5("InNULL");
   try {
     logger.info("查询ID: " + _id + " 的MD5值");
     System.out.println("查询ID:" + _id);
     DBObject dBObject = collection.findOne(new BasicDBObject("id", Integer.parseInt(_id)));
     if (null == dBObject) {
       logger.warn("撞库失败 没有查询到指定对象 ID: " + Integer.parseInt(_id));
       return yanedCG;
     } else {
       yanedCG.setId(Integer.parseInt(dBObject.get("id").toString()));
       yanedCG.setTags(dBObject.get("tags").toString());
       yanedCG.setMd5(dBObject.get("md5").toString());
       yanedCG.setDownComplete(Boolean.parseBoolean(dBObject.get("downComplete").toString()));
       yanedCG.setSource(dBObject.get("source").toString());
       yanedCG.setFile_url(dBObject.get("file_url").toString());
       yanedCG.setFile_size(dBObject.get("file_size").toString());
       yanedCG.setLocal_url("Has Save in Server");
       logger.info("查询到指定对象 ID: " + Integer.parseInt(_id));
       return yanedCG;
     }
   } catch (Exception e) {
     logger.error(e.getMessage());
   }
   return yanedCG;
 }