使用过滤器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“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"), CompareOp.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."); 
  }

注意事项

当前二级索引不支持使用SubstringComparator类定义的对象作为Filter的比较器。

例如，如下示例中的用法当前不支持：

Scan scan = new Scan();
filterList = new FilterList(FilterList.Operator.MUST_PASS_ALL);
filterList.addFilter(new SingleColumnValueFilter(Bytes
.toBytes(columnFamily), Bytes.toBytes(qualifier),
CompareOp.EQUAL, new SubstringComparator(substring)));
scan.setFilter(filterList);