MAPREDUCE服务 MRS-使用Filter过滤器读取HBase表数据:代码样例

时间：2024-11-01 09:29:13

MAPREDUCE服务 MRS

代码样例

以下代码片段在com.huawei.bigdata.hbase.examples包的“HBaseSample”类的testSingleColumnValueFilter方法中。

public void testSingleColumnValueFilter() {
     LOG .info("Entering testSingleColumnValueFilter.");
    Table table = null;

    ResultScanner rScanner = null;

    try {

      table = conn.getTable(tableName);

      Scan scan = new Scan();
      scan.addColumn(Bytes.toBytes("info"), Bytes.toBytes("name"));
      // Set the filter criteria.
      SingleColumnValueFilter filter = new SingleColumnValueFilter(
          Bytes.toBytes("info"), Bytes.toBytes("name"), CompareOperator.EQUAL,
          Bytes.toBytes("Xu Bing"));
      scan.setFilter(filter);
      // Submit a scan request.
      rScanner = table.getScanner(scan);
      // Print query results.
       for (Result r = rScanner.next(); r != null; r = rScanner.next()) {
         for (Cell cell : r.rawCells()) {
           LOG.info("{}:{},{},{}", Bytes.toString(CellUtil.cloneRow(cell)),
               Bytes.toString(CellUtil.cloneFamily(cell)), Bytes.toString(CellUtil.cloneQualifier(cell)),
               Bytes.toString(CellUtil.cloneValue(cell)));
        }
      }
      LOG.info("Single column value filter successfully.");
    } catch (IOException e) {
      LOG.error("Single column value filter failed " ,e);
    } finally {
        if (rScanner != null) {
            // Close the scanner object.
            rScanner.close();
          }
      if (table != null) {
        try {
          // Close the HTable object.
          table.close();
        } catch (IOException e) {
          LOG.error("Close table failed " ,e);
        }
      }
    }
    LOG.info("Exiting testSingleColumnValueFilter.");
  }

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