MAPREDUCE服务 MRS-使用Scan API读取HBase表数据:代码样例

时间：2024-06-13 09:38:27

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testScanData方法中。

public void testScanData() {
    LOG.info("Entering testScanData.");
    Table table = null; 
    // Instantiate a ResultScanner object.
    ResultScanner rScanner = null;
    try {
      // Create the Configuration instance.
      table = conn.getTable(tableName);
      // Instantiate a Get object.
      Scan scan = new Scan();
      scan.addColumn(Bytes.toBytes("info"), Bytes.toBytes("name"));
      // Set the cache size.
      scan.setCaching(1000);

      // 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("Scan data successfully.");
    } catch (IOException e) {
      LOG.error("Scan data 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 testScanData.");
  }

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