2.3-2.6 HBase java API

一、get 、put、delete、scan

1、代码

package com.beifeng.senior.hadoop.hbase;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.CellUtil;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.client.Delete;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.ResultScanner;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.io.IOUtils;

/**
 * CRUD operations
 *
 * @author root
 *
 */

public class HBaseOperation {

    public static HTable getHTableByTableName(String tableName) throws Exception {
        // get instance of default configuration
        Configuration configuration = HBaseConfiguration.create();

        // get table instance
        HTable table = new HTable(configuration, tableName);

        return table;
    }

    public void getData() throws Exception {
        String tableName = "user"; // default.user

        HTable table = getHTableByTableName(tableName);

        //create get with rowkey
        Get get = new Get(Bytes.toBytes("10002"));

        //add column
        get.addColumn(Bytes.toBytes("info"), Bytes.toBytes("name"));
        get.addColumn(Bytes.toBytes("info"), Bytes.toBytes("age"));

        //get data
        Result result = table.get(get);

        //key: rowkey + cf + c + version
        //value: value
        for(Cell cell : result.rawCells()){
            System.out.println(
                    Bytes.toString(CellUtil.cloneFamily(cell)) + ":" //
                    + Bytes.toString(CellUtil.cloneQualifier(cell)) + "->" //
                    + Bytes.toString(CellUtil.cloneValue(cell)));
        }

        //table close
        table.close();
    }

    /**
     * 建议：
     *         tablename & column family ->常量, HbaseTableContent
     *
     *         Map<String, Object>
     *
     * @throws Exception
     */

    public void putData() throws Exception {
        String tableName = "user"; // default.user

        HTable table = getHTableByTableName(tableName);

        Put put = new Put(Bytes.toBytes("10004"));

        //add a column with value
        put.add(Bytes.toBytes("info"),
                 Bytes.toBytes("name"),
                 Bytes.toBytes("zhaoliu"));

        put.add(Bytes.toBytes("info"),
                 Bytes.toBytes("age"),
                 Bytes.toBytes("25"));

        put.add(Bytes.toBytes("info"),
                 Bytes.toBytes("address"),
                 Bytes.toBytes("shanghai"));

        table.put(put);

        table.close();
    }

    public void deleteData() throws Exception {
        String tableName = "user"; // default.user

        HTable table = getHTableByTableName(tableName);

        Delete delete = new Delete(Bytes.toBytes("10004"));

        /*删除单个数据
        delete.deleteColumn(Bytes.toBytes("info"),
                                 Bytes.toBytes("address"));
        */

        /*删除整个列簇*/
        delete.deleteFamily(Bytes.toBytes("info"));

        table.delete(delete);

        table.close();
    }

    public static void main(String[] args) throws Exception {
        String tableName = "user"; // default.user

        HTable table = null;
        ResultScanner resultScanner = null;

        try {
            table = getHTableByTableName(tableName);

            /*全表扫描
            Scan scan = new Scan();
            */

            //指定Rowkey范围
            Scan scan = new Scan();

            scan.setStartRow(Bytes.toBytes("10002"));
            scan.setStopRow(Bytes.toBytes("10004"));

            resultScanner = table.getScanner(scan);

            for(Result result : resultScanner) {
                System.out.println(Bytes.toString(result.getRow()));
                //System.out.println(result);

                for(Cell cell : result.rawCells()){
                    System.out.println(
                            Bytes.toString(CellUtil.cloneFamily(cell)) + ":" //
                            + Bytes.toString(CellUtil.cloneQualifier(cell)) + "->" //
                            + Bytes.toString(CellUtil.cloneValue(cell)));
                }

                System.out.println("--------------------");
            }

        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            IOUtils.closeStream(resultScanner);
            IOUtils.closeStream(table);
        }

    }

}

HBase命令：

hbase(main):006:0> flush 'table name'        //刷数据

hbase(main):007:0> compact 'table name'    //合并数据