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Bigdata, Semantic IoT, Hadoop, NoSQL

Bigdata, Hadoop ecosystem, Semantic IoT등의 프로젝트를 진행중에 습득한 내용을 정리하는 곳입니다.
필요한 분을 위해서 공개하고 있습니다. 문의사항은 gooper@gooper.com로 메일을 보내주세요.


* 호출하는 쪽에서 사용하는 예시

if(paging) {
   // pageNumber를 100개 이내로 제한한다.
   if(pageNumber <= 0 || pageNumber >= 100) throw new NotProperRangeException("pageNumber is not in proper ranges(0 < pageNumber < 100)");
   rows=StoreUtil.listScanWithPaging(conn, tableName,Bytes.toBytes(startRow),Bytes.toBytes(stopRow), pageNumber, pageSize);
  } else {
   // maxRows를 10000개 이내로 제한한다.
   if(maxRows <= 0 || maxRows >= 10000) throw new NotProperRangeException("maxRows is not in proper ranges(0 < maxRows < 10000)");
   rows=StoreUtil.listScan(conn, tableName,Bytes.toBytes(startRow),Bytes.toBytes(stopRow),maxRows);
  }



------------------------------StoreUtil.java에 포함되는 메서드중 일부 --------------------------------

 // scan with  paging
 static public List<Map<String, byte[]>> listScanWithPaging(HConnection conn, String tableName, byte[] startRow, byte[] stopRow, int pageNumber, int pageSize) throws Exception {
  HTableInterface table = null;
  try {
   table=conn.getTable(Bytes.toBytes(tableName));
   Scan scan=new Scan(startRow);
   if(stopRow!=null)
    scan.setStopRow(stopRow);

   ResultScanner scanner = table.getScanner(scan);
   
   List<Map<String, byte[]>> rows=new LinkedList<Map<String, byte[]>>();
   int skipCnt = 1;
   int rowCnt = 1;
   
   // 잘못된 값이 들어오면 0건 return
   if(pageNumber <= 0 || pageSize <= 0) return rows;
   
   if(pageNumber == 1) pageNumber = 2;
   
   try {
    for (Result rs : scanner) {
     if(skipCnt++ <= ((pageNumber-1) * pageSize)) {
      //System.out.println("skipCnt  == > ["+(skipCnt-1)+"]");
      continue;
     } else {
      //System.out.println("includeCnt  == > ["+(skipCnt-1)+"]");
     }
     
     // 지정한 수만큼 row를 뽑아냄
     if(rowCnt++ > pageSize) break;
     
     Map<String, byte[]> m=new LinkedHashMap<String, byte[]>();
     m.put("rowId", rs.getRow());
           NavigableMap<byte[], NavigableMap<byte[], byte[]>> familyQualifierMap = rs.getNoVersionMap();
           for (byte[] familyBytes : familyQualifierMap.keySet()) {
               NavigableMap<byte[], byte[]> qualifierMap = familyQualifierMap.get(familyBytes);
               for (byte[] qualifier : qualifierMap.keySet())
                m.put(Bytes.toString(qualifier), qualifierMap.get(qualifier));
           }
     rows.add(m);
    }
   } finally {
    scanner.close();
   }
   return rows;
  } finally {
   if(table!=null)table.close();
  }
 }
 
 // count
 static public long getCount(HConnection conn, String tableName, String startRow, String stopRow) throws Exception {
  HTableInterface table = null;
  try {
   if(startRow == null || startRow.equals("")) throw new NullPointerException("startRow is null or '' ");
   if(stopRow == null || stopRow.equals("")) throw new NullPointerException("stopRow is null or '' ");
   
   table=conn.getTable(Bytes.toBytes(tableName));
   Scan scan=new Scan(Bytes.toBytes(startRow));
   if(stopRow!=null)
    scan.setStopRow(Bytes.toBytes(stopRow));

   ResultScanner scanner = table.getScanner(scan);
   
   long cnt=0L;
   try {
    for (Result rs = scanner.next(); rs != null; rs = scanner.next()) {
        cnt++;
    }   
   } finally {
    scanner.close();
   }
   return cnt;
  } finally {
   if(table!=null)table.close();
  }
 }

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