更新时间:2024-11-25 GMT+08:00
使用HBase过滤器Filter
功能简介
HBase Filter主要在Scan和Get过程中进行数据过滤,通过设置一些过滤条件来实现,如设置RowKey、列名或者列值的过滤条件。
代码样例
以下代码片段在com.huawei.bigdata.hbase.examples包的“HBaseExample”类的testFilterList方法中。
样例代码获取方式请参考获取MRS应用开发样例工程。
代码样例:
public void testFilterList() { LOG.info("Entering testFilterList."); 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")); // Instantiate a FilterList object in which filters have "and" // relationship with each other. FilterList list = new FilterList(Operator.MUST_PASS_ALL); // Obtain data with age of greater than or equal to 20. list.addFilter(new SingleColumnValueFilter(Bytes.toBytes("info"), Bytes.toBytes("age"), CompareOp.GREATER_OR_EQUAL, Bytes.toBytes(new Long(20)))); // Obtain data with age of less than or equal to 29. list.addFilter(new SingleColumnValueFilter(Bytes.toBytes("info"), Bytes.toBytes("age"), CompareOp.LESS_OR_EQUAL, Bytes.toBytes(new Long(29)))); scan.setFilter(list); // 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("Filter list successfully."); } catch (IOException e) { LOG.error("Filter list 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 testFilterList."); }
父主题: 开发HBase应用