// 设置Map规约Combinerjob.setCombinerClass(MyReducer.class);

文件内容：xiaomi 200            huawei 500xiaomi 300huawei 700iphonex 100iphonex 30iphone7 60
对上面文件内容按手机品牌分类分发到四个reduce处理计算：package rdb.com.hadoop01.mapreduce;import java.io.IOException;import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Partitioner;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;/*** * @author rdb**/
public class PartitionerApp {/*** map读取输入文件* @author rdb**/public static class MyMapper extends Mapper<LongWritable, Text, Text, LongWritable>{@Overrideprotected void map(LongWritable key, Text value,Mapper<LongWritable, Text, Text, LongWritable>.Context context)throws IOException, InterruptedException {//接收每一行数据String line = value.toString();//按空格进行分割 String[] words = line.split(" ");//通过上下文把map处理结果输出context.write(new Text(words[0]), new LongWritable(Long.parseLong(words[1])));}}/*** reduce程序，归并统计* @author rdb**/public static class MyReduce extends Reducer<Text, LongWritable, Text, LongWritable>{@Overrideprotected void reduce(Text key, Iterable<LongWritable> values,Reducer<Text, LongWritable, Text, LongWritable>.Context context)throws IOException, InterruptedException {long sum = 0;for (LongWritable value : values){//求单词次数sum += value.get();}//通过上下文把reduce处理结果输出context.write(key, new LongWritable(sum));}}/*** 自定义partition* @author rdb**/public static class MyPartitioner extends Partitioner<Text, LongWritable>{@Overridepublic int getPartition(Text key, LongWritable value, int numPartitions) {if(key.toString().equals("xiaomi")){return 0;}if(key.toString().equals("huawei")){return 1;}if(key.toString().equals("iphonex")){return 2;}return 3;}}/*** 自定义driver:封装mapreduce作业所有信息*@param args* @throws IOException */public static void main(String[] args) throws Exception {//创建配置Configuration configuration = new Configuration();//清理已经存在的输出目录Path out = new Path(args[1]);FileSystem fileSystem = FileSystem.get(configuration);if(fileSystem.exists(out)){fileSystem.delete(out, true);System.out.println("output exists,but it has deleted");}//创建jobJob job = Job.getInstance(configuration,"WordCount");//设置job的处理类job.setJarByClass(PartitionerApp.class);//设置作业处理的输入路径FileInputFormat.setInputPaths(job, new Path(args[0]));//设置map相关的参数job.setMapperClass(MyMapper.class);job.setMapOutputKeyClass(Text.class);job.setMapOutputValueClass(LongWritable.class);//设置reduce相关参数job.setReducerClass(MyReduce.class);job.setOutputKeyClass(Text.class);job.setOutputValueClass(LongWritable.class);//设置combiner处理类，逻辑上和reduce是一样的//job.setCombinerClass(MyReduce.class);//设置job partitionjob.setPartitionerClass(MyPartitioner.class);//设置4个reducer,每个分区一个 job.setNumReduceTasks(4);//设置作业处理的输出路径FileOutputFormat.setOutputPath(job, new Path(args[1]));System.exit(job.waitForCompletion(true)? 0 : 1) ;}
}打包后调用：hadoop jar ~/lib/hadoop01-0.0.1-SNAPSHOT.jar rdb.com.hadoop01.mapreduce.PartitionerApp
hdfs://hadoop01:8020/partitioner.txt  hdfs://hadoop01:8020/output/partitioner结果： -rw-r--r--   1 hadoop supergroup         11 2018-05-09 06:35 /output/partitioner/part-r-00000-rw-r--r--   1 hadoop supergroup         12 2018-05-09 06:35 /output/partitioner/part-r-00001-rw-r--r--   1 hadoop supergroup         12 2018-05-09 06:35 /output/partitioner/part-r-00002-rw-r--r--   1 hadoop supergroup         11 2018-05-09 06:35 /output/partitioner/part-r-00003[hadoop@hadoop01 lib]$ hadoop fs -text /output/partitioner/part-r-00000
18/05/09 06:36:37 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
xiaomi  500
[hadoop@hadoop01 lib]$ hadoop fs -text /output/partitioner/part-r-00001
18/05/09 06:36:43 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
huawei  1200
[hadoop@hadoop01 lib]$ hadoop fs -text /output/partitioner/part-r-00002
18/05/09 06:36:49 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
iphonex 130
[hadoop@hadoop01 lib]$ hadoop fs -text /output/partitioner/part-r-00003
18/05/09 06:36:57 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
iphone7 60

<property><name>mapreduce.jobhistory.address</name><value>hadoop01:10020</value><description>MR JobHistory Server管理的日志的存放位置</description>
</property>
<property><name>mapreduce.jobhistory.webapp.address</name><value>hadoop01:19888</value><description>查看历史服务器已经运行完的Mapreduce作业记录的web地址，需要启动该服务才行</description>
</property>
<property><name>mapreduce.jobhistory.done-dir</name><value>/history/done</value><description>MR JobHistory Server管理的日志的存放位置,默认:/mr-history/done</description>
</property>
<property><name>mapreduce.jobhistory.intermediate-done-dir</name><value>/history/done_intermediate</value><description>MapReduce作业产生的日志存放位置，默认值:/mr-history/tmp</description>
</property>

[hadoop@hadoop01 sbin]$ jps
24321 JobHistoryServer
24353 Jps
23957 NodeManager
7880 DataNode
8060 SecondaryNameNode
23854 ResourceManager
7791 NameNode
[hadoop@hadoop01 sbin]$