HBase Shell is written in JRuby. As JRuby runs within Java Virtual Machine (JVM) , it is very easy to execute Java methods from HBase Shell. HBase ships with many Java utility classes; the ability to execute Java methods from HBase Shell makes it possible to import and use these utilities directly from HBase Shell.
HBase Shell 使用JRuby编写。JRuby运行在Java虚拟机内（JVM），使的在HBase Shell 中运行java程序变得非常简单，HBase附带了许多Java工具类；我们可以直接从HBase shell中引入并使用java的类库。
首先确保hbase启动正常，查看进程，运行jps，保证这三个进程正常启动
19467 HMaster
19744 HRegionServer
19394 HQuorumPeer
启动hbase shell
> hbase shell
查看加载的类库：
jruby-1.7.19 :008 > $LOAD_PATH
=> [#<Pathname:/usr/hbase-cdh/lib/ruby>, "file:/usr/hbase-cdh/lib/jruby-complete-1.6.8.jar!/META-INF/jruby.home/lib/ruby/site_ruby/1.8", "file:/usr/hbase-cdh/lib/jruby-complete-1.6.8.jar!/META-INF/jruby.home/lib/ruby/site_ruby/shared", "file:/usr/hbase-cdh/lib/jruby-complete-1.6.8.jar!/META-INF/jruby.home/lib/ruby/1.8", "."]
相应的jar包已经在加载路径中，在程序中可以直接引用，在shell中直接输入如下内容：
include Java
import org.apache.hadoop.hbase.HBaseConfiguration
import org.apache.hadoop.hbase.HColumnDescriptor
import org.apache.hadoop.hbase.HConstants
import org.apache.hadoop.hbase.HTableDescriptor
import org.apache.hadoop.hbase.client.HBaseAdmin
import org.apache.hadoop.hbase.client.HTable
import org.apache.hadoop.io.Text
conf = HBaseConfiguration.new
tablename = "test_links"
desc = HTableDescriptor.new(tablename)
desc.addFamily(HColumnDescriptor.new("core"))
desc.addFamily(HColumnDescriptor.new("meta"))
desc.addFamily(HColumnDescriptor.new("stats"))
在hbase中创建表
admin = HBaseAdmin.new(conf)
if admin.tableExists(tablename)
admin.disableTable(tablename)
admin.deleteTable(tablename)
end
admin.createTable(desc)
tables = admin.listTables
p [:tables, tables]
以上是在hbase shell中运行的结果，下面我们来来看如何直接使用jruby脚本来访问hbase，不同的是我们需要手动的去加载相应的jar包，才能正常的引入，完整代码如下：
include Java
hbase_home = '/usr/hbase-cdh'
jar_paths = Dir.glob(File.join(File.dirname("#{hbase_home}/lib/"),"lib","*.jar"))
jar_paths.each {|jar| require jar}
import org.apache.hadoop.hbase.HBaseConfiguration
import org.apache.hadoop.hbase.HColumnDescriptor
import org.apache.hadoop.hbase.HConstants
import org.apache.hadoop.hbase.HTableDescriptor
import org.apache.hadoop.hbase.client.HBaseAdmin
import org.apache.hadoop.hbase.client.HTable
import org.apache.hadoop.io.Text
conf = HBaseConfiguration.new
tablename = "test_links"
desc = HTableDescriptor.new(tablename)
desc.addFamily(HColumnDescriptor.new("core"))
desc.addFamily(HColumnDescriptor.new("meta"))
desc.addFamily(HColumnDescriptor.new("stats"))
admin = HBaseAdmin.new(conf)
if admin.tableExists(tablename)
admin.disableTable(tablename)
admin.deleteTable(tablename)
end
admin.createTable(desc)
tables = admin.listTables
p [:tables, tables]
测试：
jruby -S jruby_connect_hbase.rb
[:tables, org.apache.hadoop.hbase.HTableDescriptor['mac-history', {NAME => 'info', DATA_BLOCK_ENCODING => 'FAST_DIFF', BLOOMFILTER => 'ROW', REPLICATION_SCOPE => '0', VERSIONS => '1', COMPRESSION => 'NONE', MIN_VERSIONS => '0', TTL => 'FOREVER', KEEP_DELETED_CELLS => 'false', BLOCKSIZE => '16384', IN_MEMORY => 'false', BLOCKCACHE => 'true'}, 'shop-blacklist', {NAME => 'info', DATA_BLOCK_ENCODING => 'FAST_DIFF', BLOOMFILTER => 'ROW', REPLICATION_SCOPE => '0', VERSIONS => '1', COMPRESSION => 'NONE', MIN_VERSIONS => '0', TTL => 'FOREVER', KEEP_DELETED_CELLS => 'false', BLOCKSIZE => '16384', IN_MEMORY => 'false', BLOCKCACHE => 'true'}, 'shop-daily-counter', {NAME => 'info', DATA_BLOCK_ENCODING => 'FAST_DIFF', BLOOMFILTER => 'ROW', REPLICATION_SCOPE => '0', VERSIONS => '50', COMPRESSION => 'NONE', MIN_VERSIONS => '0', TTL => 'FOREVER', KEEP_DELETED_CELLS => 'false', BLOCKSIZE => '16384', IN_MEMORY => 'false', BLOCKCACHE => 'true'}, 'shop-daily-profile', {NAME => 'info', DATA_BLOCK_ENCODING => 'FAST_DIFF', BLOOMFILTER => 'ROW', REPLICATION_SCOPE => '0', VERSIONS => '1', COMPRESSION => 'NONE', MIN_VERSIONS => '0', TTL => 'FOREVER', KEEP_DELETED_CELLS => 'false', BLOCKSIZE => '16384', IN_MEMORY => 'false', BLOCKCACHE => 'true'}, 'test_links', {NAME => 'core', DATA_BLOCK_ENCODING => 'NONE', BLOOMFILTER => 'ROW', REPLICATION_SCOPE => '0', VERSIONS => '1', COMPRESSION => 'NONE', MIN_VERSIONS => '0', TTL => 'FOREVER', KEEP_DELETED_CELLS => 'false', BLOCKSIZE => '65536', IN_MEMORY => 'false', BLOCKCACHE => 'true'}, {NAME => 'meta', DATA_BLOCK_ENCODING => 'NONE', BLOOMFILTER => 'ROW', REPLICATION_SCOPE => '0', VERSIONS => '1', COMPRESSION => 'NONE', MIN_VERSIONS => '0', TTL => 'FOREVER', KEEP_DELETED_CELLS => 'false', BLOCKSIZE => '65536', IN_MEMORY => 'false', BLOCKCACHE => 'true'}, {NAME => 'stats', DATA_BLOCK_ENCODING => 'NONE', BLOOMFILTER => 'ROW', REPLICATION_SCOPE => '0', VERSIONS => '1', COMPRESSION => 'NONE', MIN_VERSIONS => '0', TTL => 'FOREVER', KEEP_DELETED_CELLS => 'false', BLOCKSIZE => '65536', IN_MEMORY => 'false', BLOCKCACHE => 'true'}]@89c9ec7]
