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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cn.chinatelecom.hbase.sample包的“HBaseSample”类的
sampleScanFilter方法中。
public static List<String> sampleScanFilter(Connection conn) {
        List<String> list = new ArrayList<>();
        TableName tableName = TableName.valueOf("hbase-sample");
        Scan scan = new Scan();
        scan.addColumn(Bytes.toBytes("user"), Bytes.toBytes("name"));
        SingleColumnValueFilter filter = new SingleColumnValueFilter(
                Bytes.toBytes("user"), Bytes.toBytes("name"), CompareOperator.EQUAL,
                Bytes.toBytes("Zhang San"));
        scan.setFilter(filter);
        try (Table table = conn.getTable(tableName); ResultScanner rScanner = table.getScanner(scan)) {
            for (Result result : rScanner) {
                showData(list, result);
            }
            log.info("Scan filter data successfully");
        } catch (IOException e) {
            log.error("Scan filter data failed ", e);
        }
        return list;
}

private static void showData(List<String> list, Result result) {
        for (Cell cell : result.rawCells()) {
            String temp = Bytes.toString(CellUtil.cloneRow(cell)) + ":"
                    + Bytes.toString(CellUtil.cloneFamily(cell)) + ","
                    + Bytes.toString(CellUtil.cloneQualifier(cell)) + ","
                    + Bytes.toString(CellUtil.cloneValue(cell));
            log.info(temp);
            list.add(temp);
        }
    }
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),
CompareOperator.EQUAL, new SubstringComparator(substring)));
scan.setFilter(filterList);