HBase用戶端API-過濾器

在使用HBase的API查詢資料的時候，我們經常需要設定一些過濾條件來查詢資料，這個時候我們就需要使用 HBase API 的各種 Filter 來實現這一功能。

在 HBase API 中使用過濾器需要建立一個 Filter 執行個體，然後使用Scan.setFilter()或者Get.setFilter()來使用 Filter，如下：

Table table = connection.getTable(TableName.valueOf(TABLE_NAME));Scan scan = new Scan();Filter filter = new RowFilter(CompareOperator.EQUAL, new BinaryComparator(Bytes.toBytes("row_2")));scan.setFilter(filter);ResultScanner resultScanner = table.getScanner(scan);Iterator<Result> it = resultScanner.iterator();while (it.hasNext()) {    Result result = it.next();    printRow(result);}resultScanner.close();table.close();

在 HBase API 中提供了大量的 Filter 實現，比如一些常見的 Filter： RowFilter: 過濾指定的行記錄 FamilyFilter: 過濾指定的列族，其它列族返回null QualifierFilter: 過濾指定的列，其它列返回null ValueFilter: 過濾指定的值，，其它列返回null SingleColumnValueFilter: 單列值過濾器 SingleColumnValueExcludeFilter: 單列值排除過濾器，被排除的列返回null PageFilter: 分頁過濾器 ColumnPaginationFilter: 列分頁過濾器 …

在 HBase API 提供了一些常用比較子，這些寫比較子可以用來比較過濾器中的值，如： CompareOperator.LESS CompareOperator.LESS_OR_EQUAL CompareOperator.EQUAL CompareOperator.NOT_EQUAL CompareOperator.GREATOR CompareOperator.GREATOR_OR_EQUAL CompareOperator.NO_OP

在 HBase API 還提供了一些常用比較子，這些寫比較子可以用來比較過濾器中的值，如： BinaryComparator RegexStringComparator NullComparator SubstringComparator …

下面是一段完整的列子是怎樣，看看使用各種 Filter

package my.hbasestudy;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.hbase.CompareOperator;import org.apache.hadoop.hbase.HBaseConfiguration;import org.apache.hadoop.hbase.TableName;import org.apache.hadoop.hbase.client.*;import org.apache.hadoop.hbase.exceptions.DeserializationException;import org.apache.hadoop.hbase.filter.*;import org.apache.hadoop.hbase.util.Bytes;import java.io.IOException;import java.util.ArrayList;import java.util.Iterator;import java.util.List;public class TestFilter {    private static final String TABLE_NAME = "user";    private static final String COLUMN_FAMILY_BASE = "base";    private static final String COLUMN_FAMILY_ADDRESS = "address";    private static final String COLUMN_USERNAME = "username";    private static final String COLUMN_PASSWORD = "password";    private static final String COLUMN_HOME = "home";    private static final String COLUMN_OFFICE = "office";    private Connection connection;    public static void main(String[] args) throws Exception {        Configuration config = HBaseConfiguration.create();        Connection connection = ConnectionFactory.createConnection(config);        TestFilter t = new TestFilter(connection);        t.test();        connection.close();    }    public TestFilter(Connection connection) {        this.connection = connection;    }    private void test() throws IOException, DeserializationException {        createTable();        prepare();        System.out.println("---------- Row Filter ----------");        filter(new RowFilter(CompareOperator.EQUAL, new BinaryComparator(Bytes.toBytes("row_2"))));        filter(new RowFilter(CompareOperator.LESS_OR_EQUAL, new BinaryComparator(Bytes.toBytes("row_5"))));        filter(new RowFilter(CompareOperator.EQUAL, new RegexStringComparator("row_*")));        System.out.println("---------- Family Filter ----------");        filter(new FamilyFilter(CompareOperator.EQUAL, new BinaryComparator(Bytes.toBytes("base"))));        filter(new FamilyFilter(CompareOperator.EQUAL, new RegexStringComparator("address*")));        System.out.println("---------- Column Filter ----------");        filter(new QualifierFilter(CompareOperator.EQUAL, new BinaryComparator(Bytes.toBytes("username"))));        filter(new QualifierFilter(CompareOperator.EQUAL, new RegexStringComparator("home*")));        System.out.println("---------- Value Filter ----------");        filter(new ValueFilter(CompareOperator.EQUAL, new BinaryComparator(Bytes.toBytes("user_0"))));        filter(new ValueFilter(CompareOperator.EQUAL, new RegexStringComparator("password_*")));        System.out.println("---------- Single Column Value Filter ----------");        filter(new SingleColumnValueFilter(Bytes.toBytes("base"), Bytes.toBytes("username"),                CompareOperator.EQUAL, new BinaryComparator(Bytes.toBytes("user_0"))));        System.out.println("---------- Single Column Value Exclude Filter ----------");        filter(new SingleColumnValueExcludeFilter(Bytes.toBytes("base"), Bytes.toBytes("username"),                CompareOperator.EQUAL, new BinaryComparator(Bytes.toBytes("user_0"))));        deleteTable();    }    private void createTable() throws IOException {        Admin admin = connection.getAdmin();        try {            TableDescriptor tableDesc = TableDescriptorBuilder.newBuilder(TableName.valueOf(TABLE_NAME))                    .addColumnFamily(ColumnFamilyDescriptorBuilder.newBuilder(Bytes.toBytes(COLUMN_FAMILY_BASE)).build())                    .addColumnFamily(ColumnFamilyDescriptorBuilder.newBuilder(Bytes.toBytes(COLUMN_FAMILY_ADDRESS)).build())                    .build();            admin.createTable(tableDesc);        } finally {            admin.close();        }    }    private void deleteTable() throws IOException {        Admin admin = connection.getAdmin();        try {            admin.disableTable(TableName.valueOf(TABLE_NAME));            admin.deleteTable(TableName.valueOf(TABLE_NAME));        } finally {            admin.close();        }    }    private void prepare() throws IOException {        Table table = connection.getTable(TableName.valueOf(TABLE_NAME));        List<Row> actions = new ArrayList<Row>();        for (int i = 0; i < 10; i++) {            Put put = new Put(Bytes.toBytes("row_" + i));            put.addColumn(Bytes.toBytes(COLUMN_FAMILY_BASE), Bytes.toBytes(COLUMN_USERNAME), Bytes.toBytes("user_" + i));            put.addColumn(Bytes.toBytes(COLUMN_FAMILY_BASE), Bytes.toBytes(COLUMN_PASSWORD), Bytes.toBytes("password_" + i));            put.addColumn(Bytes.toBytes(COLUMN_FAMILY_ADDRESS), Bytes.toBytes(COLUMN_HOME), Bytes.toBytes("home_" + i));            put.addColumn(Bytes.toBytes(COLUMN_FAMILY_ADDRESS), Bytes.toBytes(COLUMN_OFFICE), Bytes.toBytes("office_" + i));            actions.add(put);        }        Object[] results = new Object[actions.size()];        try {            table.batch(actions, results);        } catch (InterruptedException e) {            e.printStackTrace();        }        table.close();    }    private void filter(Filter filter) throws IOException {        Table table = connection.getTable(TableName.valueOf(TABLE_NAME));        Scan scan = new Scan();        scan.setFilter(filter);        ResultScanner resultScanner = table.getScanner(scan);        Iterator<Result> it = resultScanner.iterator();        while (it.hasNext()) {            Result result = it.next();            printRow(result);        }        resultScanner.close();        table.close();    }    private void printRow(Result result) {        if (Bytes.toString(result.getRow()) != null) {            StringBuilder sb = new StringBuilder();            sb.append(Bytes.toString(result.getRow()));            sb.append("[");            sb.append("base:username=" + Bytes.toString(result.getValue(Bytes.toBytes("base"), Bytes.toBytes("username"))));            sb.append(", base:password=" + Bytes.toString(result.getValue(Bytes.toBytes("base"), Bytes.toBytes("password"))));            sb.append(", address:home=" + Bytes.toString(result.getValue(Bytes.toBytes("address"), Bytes.toBytes("home"))));            sb.append(", address:office=" + Bytes.toString(result.getValue(Bytes.toBytes("address"), Bytes.toBytes("office"))));            sb.append("]");            System.out.println(sb.toString());        }    }}