HBase-建表(普通建表及预分区建表)

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package com.hbase.HBaseAdmin;
 
import java.io.IOException;
 
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.Admin;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;
import org.apache.hadoop.hbase.client.RegionLocator;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.Pair;
 
 
/**
* @author:FengZhen
* @create:2018年9月6日
*/
public class CreateTable {
 
    private static String addr="HDP233,HDP232,HDP231";
    private static String port="2181";
    private static Connection connection;
     
    /**
     * 获取连接
     */
    public static void getConnection(){
        Configuration conf = HBaseConfiguration.create();
 
        conf.set("hbase.zookeeper.quorum",addr);
        conf.set("hbase.zookeeper.property.clientPort", port);
        try {
            connection = ConnectionFactory.createConnection(conf);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
     
    /*
     * 关闭连接
     */
    public static void close() {
        /**
         * close connection
         **/
        if (connection != null) {
            try {
                connection.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
     
    public static void main(String[] args) {
        createTablePrePartition();
    }
     
    /**
     * 建表
     */
    public static void createTable() {
        getConnection();
        try {
            //获取admin实例
            Admin admin = connection.getAdmin();
            //创建表描述符
            HTableDescriptor tableDescriptor = new HTableDescriptor(TableName.valueOf("test_create"));
            //添加列族描述符到表描述符中
            HColumnDescriptor columnDescriptor = new HColumnDescriptor(Bytes.toBytes("info"));
            tableDescriptor.addFamily(columnDescriptor);
            //调用create方法
            admin.createTable(tableDescriptor);
            //检查表是否可用
            boolean avail = admin.isTableAvailable(TableName.valueOf("test_create"));
            System.out.println("Table available: " + avail);
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            close();
        }
    }
     
    //---------------------------------------通过预分区建表-----------------------------------------
    /**
     *  Printing regions of table: test_pre_partition1
        [1]start key: ,end key:1
        [2]start key:1 ,end key:13
        [3]start key:13 ,end key:25
        [4]start key:25 ,end key:37
        [5]start key:37 ,end key:49
        [6]start key:49 ,end key:61
        [7]start key:61 ,end key:73
        [8]start key:73 ,end key:85
        [9]start key:85 ,end key:100
        [10]start key:100 ,end key:
        Printing regions of table: test_pre_partition2
        [1]start key: ,end key:A
        [2]start key:A ,end key:D
        [3]start key:D ,end key:G
        [4]start key:G ,end key:K
        [5]start key:K ,end key:O
        [6]start key:O ,end key:T
        [7]start key:T ,end key:
     */
    /**
     * 打印表中region信息
     * @param tableName
     * @throws IOException
     */
    public static void printTableRegions(String tableName) throws IOException {
        System.out.println("Printing regions of table: " + tableName);
        //返回表中所有region的起始行键与终止行键列表
        RegionLocator regionLocator = connection.getRegionLocator(TableName.valueOf(tableName));
        //获取所有region的边界。
        //第一个region的起始行键与最后一个region的终止行键都是空字节，这是HBase中默认的规则
        //起始和终止行键都是已经计算好的，或是提供给用户的拆分键。
        //需要注意的是，前一个region的终止行键与后一个region的起始行键是串联起来的
        //终止行键不包含在前一个region中，而是作为起始行键包含在后一个region中。
        Pair<byte[][], byte[][]> pair = regionLocator.getStartEndKeys();
        for(int n = 0; n < pair.getFirst().length; n++) {
            byte[] sk = pair.getFirst()[n];
            byte[] ek = pair.getSecond()[n];
            System.out.println("[" + (n + 1) + "]" + 
            "start key:" + (sk.length == 8 ? Bytes.toLong(sk) : Bytes.toStringBinary(sk)) + 
            " ,end key:" + (ek.length == 8 ? Bytes.toLong(ek) : Bytes.toStringBinary(ek)));
        }
    }
    /**
     * 通过预分区的方式建表
     * @throws IOException 
     */
    public static void createTablePrePartition() {
        getConnection();
        String tableName = "test_pre_partition1";
        String tableName2 = "test_pre_partition2";
        try {
            //获取admin实例
            Admin admin = connection.getAdmin();
            //创建表描述符
            HTableDescriptor tableDescriptor = new HTableDescriptor(TableName.valueOf(tableName));
            //添加列族描述符到表描述符中
            HColumnDescriptor columnDescriptor = new HColumnDescriptor(Bytes.toBytes("info"));
            tableDescriptor.addFamily(columnDescriptor);
            //调用create方法,同时设置region边界。
            //能够以特定数量拆分特定起始行键和特定终止行键，并创建表。
            //startKey必须小于endKey，并且numRegions需要大于等于3，否则会抛出异常，这样才能确保region有最小的集合
            //此方法使用Bytes.split()方法计算region边界，然后将计算得到的边界作为已拆分边界列表，并调用createTable(final HTableDescriptor desc, byte[][] splitKeys)方法
            admin.createTable(tableDescriptor, Bytes.toBytes(1L), Bytes.toBytes(100L), 10);
            printTableRegions(tableName); 
             
            //创建表中region的拆分行键
            byte[][] regions = new byte[][] {
                Bytes.toBytes("A"),
                Bytes.toBytes("D"),
                Bytes.toBytes("G"),
                Bytes.toBytes("K"),
                Bytes.toBytes("O"),
                Bytes.toBytes("T")
            };
            tableDescriptor.setName(TableName.valueOf(tableName2));
            //使用新表明和region的已拆分键值列表作为参数调用建表命令
            //使用已拆分行键的集合：使用了已经拆分好的region边界列表，因此结果都是与预期相符的。
            admin.createTable(tableDescriptor, regions);
            printTableRegions(tableName2);
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            close();
        }
    }
}