hbase的過濾器查詢

  hbase的過濾器有不少：大體分爲兩大類：比較過濾器和專用過濾器，過濾器的做用是在服務端判斷數據是否知足條件，而後只將知足條件的數據返回給客戶端；
hbase 過濾器的比較運算符：

LESS  -----  <
 LESS_OR_EQUAL  -----  <=
 EQUAL  -----  =
 NOT_EQUAL -----   <>
 GREATER_OR_EQUAL  ----- >=
 GREATER  -----  > 
 NO_OP   #排除全部

HBase 過濾器的比較器（指定比較機制）：

BinaryComparator 按字節索引順序比較指定字節數組，採用 Bytes.compareTo(byte[])
BinaryPrefixComparator 跟前面相同，只是比較左端的數據是否相同
NullComparator 判斷給定的是否爲空
BitComparator 按位比較
RegexStringComparator 提供一個正則的比較器，僅支持 EQUAL 和非 EQUAL
SubstringComparator 判斷提供的子串是否出如今 value 中。

1. 比較過濾器

//行鍵過濾器 RowFilter
Filter filter1 = new RowFilter(CompareOp.LESS_OR_EQUAL, new
BinaryComparator(Bytes.toBytes("user0000")));
scan.setFilter(filter1);

//列簇過濾器 FamilyFilter
Filter filter1 = new FamilyFilter(CompareOp.LESS, new
BinaryComparator(Bytes.toBytes("base_info")));
scan.setFilter(filter1);

//列過濾器 QualifierFilter
Filter filter = new QualifierFilter(CompareOp.LESS_OR_EQUAL, new
BinaryComparator(Bytes.toBytes("name")));
scan.setFilter(filter1);

//值過濾器 ValueFilter
Filter filter = new ValueFilter(CompareOp.EQUAL, new SubstringComparator("zhangsan") );
scan.setFilter(filter1);

//時間戳過濾器 TimestampsFilter
List<Long> tss = new ArrayList<Long>();
tss.add(1495398833002l);
Filter filter1 = new TimestampsFilter(tss);
scan.setFilter(filter1);

2.專用過濾器

//單列值過濾器 SingleColumnValueFilter ----會返回知足條件的整行
SingleColumnValueFilter filter = new SingleColumnValueFilter(
 Bytes.toBytes("colfam1"),
 Bytes.toBytes("col-5"),
 CompareFilter.CompareOp.NOT_EQUAL,
 new SubstringComparator("val-5"));
filter.setFilterIfMissing(true); //若是不設置爲 true，則那些不包含指定 column 的行也會返回
scan.setFilter(filter1);

//單列值排除器 SingleColumnValueExcludeFilter -----返回排除了該列的結果
SingleColumnValueExcludeFilter filter = new SingleColumnValueExcludeFilter(
 Bytes.toBytes("colfam1"),
 Bytes.toBytes("col-5"),
 CompareFilter.CompareOp.NOT_EQUAL,
 new SubstringComparator("val-5"));
filter.setFilterIfMissing(true); //若是不設置爲 true，則那些不包含指定 column 的行也會返回
scan.setFilter(filter1);

//前綴過濾器 PrefixFilter----針對行鍵
Filter filter = new PrefixFilter(Bytes.toBytes("row1"));
scan.setFilter(filter1);

//列前綴過濾器 ColumnPrefixFilter
Filter filter = new ColumnPrefixFilter(Bytes.toBytes("qual2"));
scan.setFilter(filter1);

實戰案例：

public class HBase_Filter01 {
    private static String ZK_KEY = "hbase.zookeeper.quorum";
    private static String ZK_VALUE = "hadoop01:2181,hadoop02:2181,hadoop03:2181";
    private static Configuration conf;
    private static Connection connection;
    private static Admin admin;
    static {
        conf = HBaseConfiguration.create();
        conf.set(ZK_KEY,ZK_VALUE);
        try {
            connection= ConnectionFactory.createConnection(conf);
            admin=connection.getAdmin();

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        Scan scan=new Scan();
        ValueFilter filter = new ValueFilter(CompareFilter.CompareOp.EQUAL, new SubstringComparator("a"));
        scan.setFilter(filter);
        TableName tableName =TableName.valueOf("user_info");
        try {
            Table table = connection.getTable(tableName);
            ResultScanner scanner = table.getScanner(scan);
            Iterator<Result> iterator=scanner.iterator();
            while(iterator.hasNext()){
                 Result result = iterator.next();
                System.out.println(result.list());
                 byte[] row = result.getRow();
                System.out.println(new String(row));
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}