HBase实验（CRUD和MR入库）

前期准备

• 启动zk
• 启动HDFS
• 启动HBase

./start-hbase.sh

在HBase shell中实现CRUD操作

• 熟悉Hbase shell

1. 启动命令行客户端

./hbase shell

2. 创建表

• 指定命名空间school、表名student以及列族essential、additional,其中列族essential有列name、sex，列族additional有列interest

##创建命名空间
create_namespace 'school'

##创建表 creat '命名空间:表名',{NAME=>列族名,VERSION=>保存版本数量}
create 'school:student',{NAME => 'essential',VERSIONS => 3},{NAME => 'additional',VERSIONS => 3}

• 默认命名空间、表名teacher以及列族essential

##不指定命名空间则使用默认命名空间
create 'teacher',{NAME => 'essential'}

3. 删除、新增列族

• 在一个shell操作中删除表teacher的列族essential,并新增列族additional

##首先停用表teacher（新版本中不用）
disable 'teacher'

##删除列族
alter 'teacher',NAME => 'essential',METHOD => 'delete'

##或者
alter 'teacher','delete' => 'essential'

##新增列族additional，不指定版本数则默认为3
alter 'teacher', NAME => 'additional'

## 或者在新增列簇时指定版本数
alter 'teacher', NAME => 'additional',VERSIONS => 220

##添加列族additiona同时删除列族essential
alter 'teacher',{NAME => 'essential'},{NAME =>'essential',METHOD => 'delete'}

##启用表
enable 'teacher'

4. 删除表teacher

## 禁用表teacher
disable 'teacher'

## 删除表teacher
drop 'teacher'

##清空表数据
truncate 'teacher'

5. 新增数据

• 向student表新增至少5条数据，其中某个cell至少拥有两个版本

## put 'table name','row','Column family:column name','new value'

##插入五条数据
##第一条
put 'school:student','0001','essential:name','xiaoming'
put 'school:student','0001','essential:sex','male'
put 'school:student','0001','additional:interest','sing'

##第二条
put 'school:student','0002','essential:name','xiaodong'
put 'school:student','0002','essential:sex','male'
put 'school:student','0002','additional:interest','ball'

##此后三条以此类推

##使第一条的additional:interest有两个版本
put 'school:student','0001','additional:interest','swiming'

##查看additional列族中字段interest是两个版本的信息

get 'school:student','0001',{COLUMN=>'additional:interest',VERSIONS=>2}

6. 查看数据

#查看所有数据
scan 'school:student'

#查看前10条数据
scan 'student',{LIMIT=>10}

#查看某一行的数据
get 'student','0001',{COLUMN=>'additional',VERSIONS=>3000}

用Java API实现CRUD操作

工程结构

1. 导入依赖包

导入HBase安装包目录中lib目录的所有jar包

2. 调用Java API

package cn.bigdata.hbase;

import java.util.ArrayList;

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.KeyValue;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.HBaseAdmin;
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;

public class HbaseDAO {

	public static void main(String[] args) throws Exception{
		
		switch (args[0]) {
        case "create":
            new HbaseDAO().createTable();
            break;
        case "put":
            new HbaseDAO().put();
            break;
        case "scan":
            new HbaseDAO().scan();

        default:
            System.out.println("first arg is " + args[0] + "enter true args");
        }
				
		
	}
	
	//创建表
	public void createTable() throws Exception{
		
		//设置配置文件
		Configuration conf = HBaseConfiguration.create();
		conf.set("hbase.zookeeper.quorum", "master:2181,slave1:2181,slave2:2181");
		
		//hbase客户端实例
		HBaseAdmin admin = new HBaseAdmin(conf);
		
		//指定表名
		TableName name = TableName.valueOf("teacher");
				
		//向表描述里添加表名
		HTableDescriptor desc = new HTableDescriptor(name);
				
		//指定列族名和版本数
		HColumnDescriptor essential = new HColumnDescriptor("essential");
		HColumnDescriptor additional = new HColumnDescriptor("additional");
		essential.setMaxVersions(3);
		additional.setMaxVersions(3);
		
		//向表描述里添加列族
		desc.addFamily(essential);
		desc.addFamily(additional);
		
		//创建表
		admin.createTable(desc);
		
		admin.close();
	}
	
	//新增数据
	public void put()throws Exception{
		//设置配置文件
		Configuration conf = HBaseConfiguration.create();
		conf.set("hbase.zookeeper.quorum", "master:2181,slave1:2181,slave2:2181");
		
		//得到表实例
		HTable teacher = new HTable(conf,"teacher");
		
		//一个Put对象需要用行键实例化，可以add多个键值对，包含行键，列族，列名，值，HBase中存储的数据类型为Byte
		//第一条数据
        Put put1 = new Put(Bytes.toBytes("rk0001"));
        put1.add(Bytes.toBytes("essential"), Bytes.toBytes("name"), Bytes.toBytes("xiaoming"));
        put1.add(Bytes.toBytes("essential"), Bytes.toBytes("sex"), Bytes.toBytes("male"));
        put1.add(Bytes.toBytes("additional"), Bytes.toBytes("interest"), Bytes.toBytes("ball"));
        
        //第二条数据
        Put put2 = new Put(Bytes.toBytes("rk0002"));
        put2.add(Bytes.toBytes("essential"), Bytes.toBytes("name"), Bytes.toBytes("xiaodong"));
        put2.add(Bytes.toBytes("essential"), Bytes.toBytes("sex"), Bytes.toBytes("male"));
        put2.add(Bytes.toBytes("additional"), Bytes.toBytes("interest"), Bytes.toBytes("play"));
        
        //第三条数据
        Put put3 = new Put(Bytes.toBytes("rk0003"));
        put3.add(Bytes.toBytes("essential"), Bytes.toBytes("name"), Bytes.toBytes("xiaohong"));
        put3.add(Bytes.toBytes("essential"), Bytes.toBytes("sex"), Bytes.toBytes("female"));
        put3.add(Bytes.toBytes("additional"), Bytes.toBytes("interest"), Bytes.toBytes("study"));
        
        //第四条数据
        Put put4 = new Put(Bytes.toBytes("rk0004"));
        put4.add(Bytes.toBytes("essential"), Bytes.toBytes("name"), Bytes.toBytes("xiaohua"));
        put4.add(Bytes.toBytes("essential"), Bytes.toBytes("sex"), Bytes.toBytes("female"));
        put4.add(Bytes.toBytes("additional"), Bytes.toBytes("interest"), Bytes.toBytes("sing"));
        
        //第五条数据
        Put put5 = new Put(Bytes.toBytes("rk0005"));
        put5.add(Bytes.toBytes("essential"), Bytes.toBytes("name"), Bytes.toBytes("xiaolong"));
        put5.add(Bytes.toBytes("essential"), Bytes.toBytes("sex"), Bytes.toBytes("male"));
        put5.add(Bytes.toBytes("additional"), Bytes.toBytes("interest"), Bytes.toBytes("box"));
        
        //增加第一条的一个cell版本
        put1.add(Bytes.toBytes("additional"), Bytes.toBytes("interest"), Bytes.toBytes("swimming"));
        
        ArrayList puts = new ArrayList<>();
        puts.add(put1);
        puts.add(put2);
        puts.add(put3);
        puts.add(put4);
        puts.add(put5);
        
        teacher.put(puts);
        teacher.close();
	}
	
	//扫描表
	@SuppressWarnings("deprecation")
	public void scan()throws Exception{
		//设置配置文件
		Configuration conf = HBaseConfiguration.create();
		conf.set("hbase.zookeeper.quorum", "master:2181,slave1:2181,slave2:2181");
				
		//得到表实例
		HTable teacher = new HTable(conf,"teacher");
		
		Scan scan = new Scan();
		
		//得到扫描结果
		ResultScanner rs = teacher.getScanner(scan);
		
		//在控制台显示
		for(Result r : rs){
			for(KeyValue kValue : r.list()) {
				
				System.out.print("Row Name:" + new String(kValue.getRow()) + "   ");
				
				System.out.print("Column Family:" + new String(kValue.getFamily())+ "   ");
				
				System.out.print("Key:" + new String(kValue.getQualifier())+ "   ");
				
				System.out.println("Value:" + new String(kValue.getValue()));				
			}
        }
        rs.close();
        teacher.close();
		
	}
            	
}

3. 导出hbasedemo.jar包

4. 将HBase依赖包加入到hadoop classpath中

在hadoop安装目录下找到hadoop-env.sh文件，添加 :

export HADOOP_CLASSPATH=/home/hadoop/apps/hbase/lib/*

5. 运行

#创建表
hadoop jar hbasedemo.jar cn.bigdata.hbase.HbaseDAO create

#插入数据
hadoop jar hbasedemo.jar cn.bigdata.hbase.HbaseDAO put

#扫描表
hadoop jar hbasedemo.jar cn.bigdata.hbase.HbaseDAO scan

注：也可直接在eclipse中运行（跳过3、5步骤），因为要访问zookeeper，所以要修改eclipse所在主机的hosts文件，确保可以ping通zookeeper的主机。

将MapReduce结果直接存储在HBase

1. 导入MapReduce和HBase依赖包

2. 代码实现

package cn.mr2hbase;
import java.io.IOException;

import org.apache.commons.lang.StringUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
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.HBaseAdmin;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.mapreduce.TableOutputFormat;
import org.apache.hadoop.hbase.mapreduce.TableReducer;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;

public class MRtoHBase {

	public static class Map extends Mapper{
		
		
		//该步骤同一般Map程序
		@Override
		protected void map(LongWritable key, Text value, Context context)
				throws IOException, InterruptedException {
			//将读入行转化为字符串
			String line = value.toString();
			//切分字符串
			String[] words = StringUtils.split(line," ");
			//将单词写入context
			for(String word:words) {
				context.write(new Text(word), new LongWritable(1));
			}
		}
		
	}
	
	public static class Reduce extends TableReducer{

		@Override
		protected void reduce(Text key, Iterable values,Context context)
				throws IOException, InterruptedException {
			long count =0;
			for(LongWritable value : values) {				
				count += value.get();
			}
			//实例化Put，将单词作为主键
			Put put = new Put(Bytes.toBytes(key.toString()));
			//列族为content，key为result，value为count
			put.add(Bytes.toBytes("content"), Bytes.toBytes("result"), Bytes.toBytes(String.valueOf(count)));
			context.write(NullWritable.get(), put);
		}
		
	}
	
	//创建表
		public static void createTable(String tablename) throws Exception{
			
			//设置配置文件
			Configuration conf = HBaseConfiguration.create();
			conf.set("hbase.zookeeper.quorum", "master:2181,slave1:2181,slave2:2181");
			
			//hbase客户端实例
			HBaseAdmin admin = new HBaseAdmin(conf);
			
			//指定表名
			TableName name = TableName.valueOf(tablename);
					
			//向表描述里添加表名
			HTableDescriptor desc = new HTableDescriptor(name);
					
			//指定列族名和版本数
			HColumnDescriptor content = new HColumnDescriptor("content");
			content.setMaxVersions(3);
			
			//向表描述里添加列族
			desc.addFamily(content);
			//判断表是否存在
			if(admin.tableExists(tablename)){  
	            System.out.println("table exists,trying recreate table !");  
	            admin.disableTable(tablename);  
	            admin.deleteTable(tablename);  
	        }  
	        System.out.println("Create new table: "+ tablename);
			
			//创建表
			admin.createTable(desc);
			
			admin.close();
		}

	public static void main(String[] args) throws Exception{
		
		String tablename = "WC";
		//创建表
		createTable(tablename);
		
		//配置文件
		Configuration conf = new Configuration();
		conf.set(TableOutputFormat.OUTPUT_TABLE, tablename);
		Job job = Job.getInstance(conf);
		
		//设置整个job所调用类的jar包路径
		job.setJarByClass(MRtoHBase.class);
		
		//设置该作业所使用的mapper和reducer类
		job.setMapperClass(Map.class);
		job.setReducerClass(Reduce.class);
		        
		//指定mapper输出数据的k-v类型，和reduce输出类型一样，可缺省
		job.setMapOutputKeyClass(Text.class);
		job.setOutputValueClass(LongWritable.class);		
				
		//指定reduce输出到Hbase
		job.setOutputKeyClass(Text.class);
		job.setOutputValueClass(LongWritable.class);		
				
		//指定输入数据存放路径
		FileInputFormat.setInputPaths(job, new Path(args[0]));		
				
		//指定输出到HBase
		job.setOutputFormatClass(TableOutputFormat.class);		
		
		//将job提交给集群运行，参数为true表示提示运行进度
		System.exit(job.waitForCompletion(true)?0:1);

	}

}

3. 导出hbasedemo.jar包

4.修改Yarn配置文件

修改集群中所有主机Hadoop配置目录下的Yarn-site.xml配置文件，添加以下属性,将Hbaselib目录下的依赖包路径配置到Yarn的class path中

    mapreduce.application.classpath
        
            /home/hadoop/app/hbase-0.96.2-hadoop2/lib/*
    

5. 运行

#在集群主机上运行
hadoop jar mrtohbase.jar cn.mr2hbase.MRtoHBase /wc/srcdata