通過HBase的相關JavaAPI,我們可以實現伴隨HBase操作的MapReduce過程,比如使用MapReduce將數據從本地文件系統導入到HBase的表中,比如我們從HBase中讀取一些原始數據後使用MapReduce做數據分析。
官方HBase-MapReduce
查看HBase的MapReduce任務的執行
$ bin/hbase mapredcp
環境變量的導入
- 執行環境變量的導入(臨時生效,在命令行執行下述操作)
$ export HBASE_HOME=/opt/module/hbase-1.3.1
$ export HADOOP_HOME=/opt/module/hadoop-2.7.2
$ export HADOOP_CLASSPATH=`${HBASE_HOME}/bin/hbase mapredcp`
- 永久生效:在/etc/profile配置
export HBASE_HOME=/opt/module/hbase-1.3.1
export HADOOP_HOME=/opt/module/hadoop-2.7.2
並在hadoop-env.sh中配置:(注意:在for循環之後配)
export HADOOP_CLASSPATH=$HADOOP_CLASSPATH:/opt/module/hbase/lib/*
運行官方的MapReduce任務
案例一:統計Student表中有多少行數據
$ /opt/module/hadoop-2.7.2/bin/yarn jar lib/hbase-server-1.3.1.jar rowcounter student
案例二:使用MapReduce將本地數據導入到HBase
- 在本地創建一個tsv格式的文件:fruit.tsv
1001 Apple Red
1002 Pear Yellow
1003 Pineapple Yellow
- 創建HBase表
hbase(main):001:0> create 'fruit','info'
- 在HDFS中創建input_fruit文件夾並上傳fruit.tsv文件
$ /opt/module/hadoop-2.7.2/bin/hdfs dfs -mkdir /input_fruit/
$ /opt/module/hadoop-2.7.2/bin/hdfs dfs -put fruit.tsv /input_fruit/
- 執行MapReduce到HBase的fruit表中
$ /opt/module/hadoop-2.7.2/bin/yarn jar lib/hbase-server-1.3.1.jar importtsv \
-Dimporttsv.columns=HBASE_ROW_KEY,info:name,info:color fruit \
hdfs://hadoop102:9000/input_fruit
- 使用scan命令查看導入後的結果
hbase(main):001:0> scan ‘fruit’
自定義HBase-MapReduce1
目標:將fruit表中的一部分數據,通過MR遷入到fruit_mr表中。
分步實現:
- 構建ReadFruitMapper類,用於讀取fruit表中的數據
import java.io.IOException;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.CellUtil;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.mapreduce.TableMapper;
import org.apache.hadoop.hbase.util.Bytes;
public class ReadFruitMapper extends TableMapper<ImmutableBytesWritable, Put> {
@Override
protected void map(ImmutableBytesWritable key, Result value, Context context)
throws IOException, InterruptedException {
//將fruit的name和color提取出來,相當於將每一行數據讀取出來放入到Put對象中。
Put put = new Put(key.get());
//遍歷添加column行
for(Cell cell: value.rawCells()){
//添加/克隆列族:info
if("info".equals(Bytes.toString(CellUtil.cloneFamily(cell)))){
//添加/克隆列:name
if("name".equals(Bytes.toString(CellUtil.cloneQualifier(cell)))){
//將該列cell加入到put對象中
put.add(cell);
//添加/克隆列:color
}else if("color".equals(Bytes.toString(CellUtil.cloneQualifier(cell)))){
//向該列cell加入到put對象中
put.add(cell);
}
}
}
//將從fruit讀取到的每行數據寫入到context中作爲map的輸出
context.write(key, put);
}
}
- 構建WriteFruitMRReducer類,用於將讀取到的fruit表中的數據寫入到fruit_mr表中
import java.io.IOException;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.mapreduce.TableReducer;
import org.apache.hadoop.io.NullWritable;
public class WriteFruitMRReducer extends TableReducer<ImmutableBytesWritable, Put, NullWritable> {
@Override
protected void reduce(ImmutableBytesWritable key, Iterable<Put> values, Context context)
throws IOException, InterruptedException {
//讀出來的每一行數據寫入到fruit_mr表中
for(Put put: values){
context.write(NullWritable.get(), put);
}
}
}
- 構建Fruit2FruitMRRunner extends Configured implements Tool用於組裝運行Job任務
//組裝Job
public int run(String[] args) throws Exception {
//得到Configuration
Configuration conf = this.getConf();
//創建Job任務
Job job = Job.getInstance(conf, this.getClass().getSimpleName());
job.setJarByClass(Fruit2FruitMRRunner.class);
//配置Job
Scan scan = new Scan();
scan.setCacheBlocks(false);
scan.setCaching(500);
//設置Mapper,注意導入的是mapreduce包下的,不是mapred包下的,後者是老版本
TableMapReduceUtil.initTableMapperJob(
"fruit", //數據源的表名
scan, //scan掃描控制器
ReadFruitMapper.class,//設置Mapper類
ImmutableBytesWritable.class,//設置Mapper輸出key類型
Put.class,//設置Mapper輸出value值類型
job//設置給哪個JOB
);
//設置Reducer
TableMapReduceUtil.initTableReducerJob("fruit_mr", WriteFruitMRReducer.class, job);
//設置Reduce數量,最少1個
job.setNumReduceTasks(1);
boolean isSuccess = job.waitForCompletion(true);
if(!isSuccess){
throw new IOException("Job running with error");
}
return isSuccess ? 0 : 1;
}
- 主函數中調用運行該Job任務
public static void main( String[] args ) throws Exception{
Configuration conf = HBaseConfiguration.create();
int status = ToolRunner.run(conf, new Fruit2FruitMRRunner(), args);
System.exit(status);
}
- 打包運行任務
$ /opt/module/hadoop-2.7.2/bin/yarn jar ~/softwares/jars/hbase-0.0.1-SNAPSHOT.jar com.z.hbase.mr1.Fruit2FruitMRRunner
提示:運行任務前,如果待數據導入的表不存在,則需要提前創建。
提示:maven打包命令:-P local clean package或-P dev clean package install(將第三方jar包一同打包,需要插件:maven-shade-plugin)
自定義HBase-MapReduce2
目標:實現將HDFS中的數據寫入到HBase表中。
分步實現:
- 構建ReadFruitFromHDFSMapper於讀取HDFS中的文件數據
import java.io.IOException;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;
public class ReadFruitFromHDFSMapper extends Mapper<LongWritable, Text, ImmutableBytesWritable, Put> {
@Override
protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
//從HDFS中讀取的數據
String lineValue = value.toString();
//讀取出來的每行數據使用\t進行分割,存於String數組
String[] values = lineValue.split("\t");
//根據數據中值的含義取值
String rowKey = values[0];
String name = values[1];
String color = values[2];
//初始化rowKey
ImmutableBytesWritable rowKeyWritable = new ImmutableBytesWritable(Bytes.toBytes(rowKey));
//初始化put對象
Put put = new Put(Bytes.toBytes(rowKey));
//參數分別:列族、列、值
put.add(Bytes.toBytes("info"), Bytes.toBytes("name"), Bytes.toBytes(name));
put.add(Bytes.toBytes("info"), Bytes.toBytes("color"), Bytes.toBytes(color));
context.write(rowKeyWritable, put);
}
}
- 構建WriteFruitMRFromTxtReducer類
import java.io.IOException;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.mapreduce.TableReducer;
import org.apache.hadoop.io.NullWritable;
public class WriteFruitMRFromTxtReducer extends TableReducer<ImmutableBytesWritable, Put, NullWritable> {
@Override
protected void reduce(ImmutableBytesWritable key, Iterable<Put> values, Context context) throws IOException, InterruptedException {
//讀出來的每一行數據寫入到fruit_hdfs表中
for(Put put: values){
context.write(NullWritable.get(), put);
}
}
}
- 創建Txt2FruitRunner組裝Job
public int run(String[] args) throws Exception {
//得到Configuration
Configuration conf = this.getConf();
//創建Job任務
Job job = Job.getInstance(conf, this.getClass().getSimpleName());
job.setJarByClass(Txt2FruitRunner.class);
Path inPath = new Path("hdfs://hadoop102:9000/input_fruit/fruit.tsv");
FileInputFormat.addInputPath(job, inPath);
//設置Mapper
job.setMapperClass(ReadFruitFromHDFSMapper.class);
job.setMapOutputKeyClass(ImmutableBytesWritable.class);
job.setMapOutputValueClass(Put.class);
//設置Reducer
TableMapReduceUtil.initTableReducerJob("fruit_mr", WriteFruitMRFromTxtReducer.class, job);
//設置Reduce數量,最少1個
job.setNumReduceTasks(1);
boolean isSuccess = job.waitForCompletion(true);
if(!isSuccess){
throw new IOException("Job running with error");
}
return isSuccess ? 0 : 1;
}
- 調用執行Job
public static void main(String[] args) throws Exception {
Configuration conf = HBaseConfiguration.create();
int status = ToolRunner.run(conf, new Txt2FruitRunner(), args);
System.exit(status);
}
- 打包運行
$ /opt/module/hadoop-2.7.2/bin/yarn jar hbase-0.0.1-SNAPSHOT.jar com.liujh.hbase.mr2.Txt2FruitRunner
提示:運行任務前,如果待數據導入的表不存在,則需要提前創建之。
提示:maven打包命令:-P local clean package或-P dev clean package install(將第三方jar包一同打包,需要插件:maven-shade-plugin)
簡書:https://www.jianshu.com/u/0278602aea1d
CSDN:https://blog.csdn.net/u012387141