HBase客户端API-过滤器

在使用HBase的API查询数据的时候，我们经常需要设置一些过滤条件来查询数据，这个时候我们就需要使用 HBase API 的各种 Filter 来实现这一功能。

在 HBase API 中使用过滤器需要创建一个 Filter 实例，然后使用Scan.setFilter()或者Get.setFilter()来使用 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 实现，比如一些常见的 Filter：

• RowFilter: 过滤指定的行记录
• FamilyFilter: 过滤指定的列族，其它列族返回null
• QualifierFilter: 过滤指定的列，其它列返回null
• ValueFilter: 过滤指定的值，，其它列返回null
• SingleColumnValueFilter: 单列值过滤器
• SingleColumnValueExcludeFilter: 单列值排除过滤器，被排除的列返回null
• PageFilter: 分页过滤器
• ColumnPaginationFilter: 列分页过滤器
• ...

在 HBase API 提供了一些常用比较运算符，这些写比较器可以用来比较过滤器中的值，如：

• CompareOperator.LESS
• CompareOperator.LESS_OR_EQUAL
• CompareOperator.EQUAL
• CompareOperator.NOT_EQUAL
• CompareOperator.GREATOR
• CompareOperator.GREATOR_OR_EQUAL
• CompareOperator.NO_OP

在 HBase API 还提供了一些常用比较器，这些写比较器可以用来比较过滤器中的值，如：

• BinaryComparator
• RegexStringComparator
• NullComparator
• SubstringComparator
• ...

下面是一段完整的列子是怎样，看看使用各种 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());
        }
    }
}