mapreduce之partition分区

短命女 2022-08-25 12:51 237阅读 0赞

听了超哥的一席课后逐渐明白了partition，记录一下自己的理解！（thanks 超哥）

package partition;
    
    import java.io.IOException;
    import java.net.URI;
    
    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.Reducer;
    import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
    import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
    import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
    import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
    
    /**
     * @ClassName: FlowCount2 
     * @Description: TODO(这里用一句话描述这个类的作用) 
     * @author zhangweixiang
     * @date 2014年3月6日 下午3:27:56
     */
    /**
     * 分区的例子必须打成jar运行
     * 用处：	1.根据业务需要，产生多个输出文件
     * 		2.多个reduce任务在运行，提高整体job的运行效率
     */
    public class FlowCount2 {
    
    	public static final String INPUT_PATH = "hdfs://192.168.0.9:9000/wlan2";
    	public static final String OUT_PATH = "hdfs://192.168.0.9:9000/myout";
    
    	public static void main(String[] args) throws Exception {
    		Configuration conf = new Configuration();
    		Job job = new Job(conf, FlowCount2.class.getSimpleName());
    		
    		//指定打包的jar
    		job.setJarByClass(FlowCount2.class);
    
    		// 1.1指定输入文件的路径
    		FileInputFormat.addInputPath(job, new Path(INPUT_PATH));
    		// 指定输入信息的格式化类
    		job.setInputFormatClass(TextInputFormat.class);
    
    		// 1.2指定自定义map类
    		job.setMapperClass(MyMapper.class);
    		// 设置map输出类型
    		job.setMapOutputKeyClass(Text.class);
    		job.setMapOutputValueClass(FlowWritable.class);
    
    		// 1.3指定分区
    		job.setPartitionerClass(MyPartition.class);
    		// 设置reduce的任务个数,由于map输出后建立了两个分区，所以应该设置两个reduce任务输出到不同的文件（一个分区对应一个reduce任务）
    		job.setNumReduceTasks(2);
    
    		// 1.4排序，分组
    
    		// 1.5规约
    
    		// 2.2指定自定义的reduce类
    		job.setReducerClass(MyReduce.class);
    		// 设置输出类型
    		job.setOutputKeyClass(Text.class);
    		job.setOutputValueClass(FlowWritable.class);
    		// 设置输出格式化类
    		job.setOutputFormatClass(TextOutputFormat.class);
    
    		// 如果输出文件路径存在则删除
    		FileSystem fileSystem = FileSystem.get(new URI(OUT_PATH),
    				new Configuration());
    		Path path = new Path(OUT_PATH);
    		if (fileSystem.exists(path)) {
    			fileSystem.delete(path, true);
    		}
    
    		// 2.3指定输出路径
    		FileOutputFormat.setOutputPath(job, new Path(OUT_PATH));
    
    		// 提交任务
    		job.waitForCompletion(true);
    
    	}
    
    	static class MyMapper extends
    			Mapper<LongWritable, Text, Text, FlowWritable> {
    		@Override
    		protected void map(LongWritable key, Text value, Context context)
    				throws IOException, InterruptedException {
    			// 分割行
    			String[] split = value.toString().split("\t");
    			// 获取用户电话号码
    			String mobile = "";
    			long upPackNum = 0l;
    			long downPackNum = 0l;
    			long upPayLoad = 0l;
    			long downPayLoad = 0l;
    
    			// 符合规范的电话号码
    			if (!("".equals(split[2]))) {
    				mobile = split[2];
    				// 获取流量信息
    				if (!("".equals(split[21]))) {
    					upPackNum = Long.parseLong(split[21]);
    				}
    				if (!("".equals(split[22]))) {
    					downPackNum = Long.parseLong(split[22]);
    				}
    				if (!("".equals(split[23]))) {
    					upPayLoad = Long.parseLong(split[23]);
    				}
    				if (!("".equals(split[24]))) {
    					downPayLoad = Long.parseLong(split[24]);
    				}
    
    				FlowWritable flowWritable = new FlowWritable(upPackNum,
    						downPackNum, upPayLoad, downPayLoad);
    
    				context.write(new Text(mobile), flowWritable);
    			}
    
    		}
    	}
    
    	static class MyReduce extends
    			Reducer<Text, FlowWritable, Text, FlowWritable> {
    		@Override
    		protected void reduce(Text k2, Iterable<FlowWritable> v2s,
    				Context context) throws IOException, InterruptedException {
    
    			long upPackNum = 0l;
    			long downPackNum = 0l;
    			long upPayLoad = 0l;
    			long downPayLoad = 0l;
    
    			for (FlowWritable flowWritable : v2s) {
    				upPackNum += flowWritable.upPackNum;
    				downPackNum += flowWritable.downPackNum;
    				upPayLoad += flowWritable.upPayLoad;
    				downPayLoad += flowWritable.downPayLoad;
    			}
    
    			FlowWritable flowWritable = new FlowWritable(upPackNum,
    					downPackNum, upPayLoad, downPayLoad);
    
    			context.write(k2, flowWritable);
    		}
    	}
    	
    
    }

package partition;
    
    import java.io.DataInput;
    import java.io.DataOutput;
    import java.io.IOException;
    
    import org.apache.hadoop.io.Writable;
    
    /**
     * @ClassName: flowWritable
     * @Description: 自定义类型实现Writable接口，包含四个参数（upPackNum 上行包， downPackNum 下行包，
     *               upPayLoad 发送流量，downPayLoad 下载流量）
     * @author zhangweixiang
     * @date 2014年3月5日 上午11:37:10
     */
    public class FlowWritable implements Writable {
    
    	public long upPackNum;
    	public long downPackNum;
    	public long upPayLoad;
    	public long downPayLoad;
    
    	public FlowWritable() {
    		// TODO Auto-generated constructor stub
    	}
    
    	public FlowWritable(long upPackNum, long downPackNum, long upPayLoad,
    			long downPayLoad) {
    		this.upPackNum = upPackNum;
    		this.downPackNum = downPackNum;
    		this.upPayLoad = upPayLoad;
    		this.downPayLoad = downPayLoad;
    	}
    
    	@Override
    	public void write(DataOutput out) throws IOException {
    		out.writeLong(upPackNum);
    		out.writeLong(downPackNum);
    		out.writeLong(upPackNum);
    		out.writeLong(downPayLoad);
    	}
    
    	@Override
    	public void readFields(DataInput in) throws IOException {
    		this.upPackNum = in.readLong();
    		this.downPackNum = in.readLong();
    		this.upPayLoad = in.readLong();
    		this.downPayLoad = in.readLong();
    	}
    
    	/*
    	 * (非 Javadoc)
    	 * 
    	 * 
    	 * @return
    	 * 
    	 * @see java.lang.Object#toString()
    	 */
    	@Override
    	public String toString() {
    		return upPackNum + "\t" + downPackNum + "\t" + upPayLoad + "\t"
    				+ downPayLoad;
    	}
    
    }

package partition;
    
    import org.apache.hadoop.io.Text;
    import org.apache.hadoop.mapreduce.lib.partition.HashPartitioner;
    /**
     * @ClassName: MyPartition 
     * @Description: 根据电话号码分区，正规号码分区代号为0，非正规号码分区为1（在此建立了两个分区，即会产生两个reduce任务输出到不同的文件0和1）
     * @param K k2(map输出的键), V v2(map输出的值)
     * @author zhangweixiang
     * @date 2014年3月6日 下午3:02:29
     */
    public class MyPartition extends HashPartitioner<Text,FlowWritable>{
    	@Override
    	public int getPartition(Text key, FlowWritable value, int numReduceTasks) {
    		int p=0;
    		if(key.toString().length()!=11){
    			p=1;
    		}
    		return p;
    	}
    }

**注：必须要达成jar包上传到linux下执行（我开始没有打成jar包直接在eclipse下执行抛了异常）**

**执行完成后会产生两个文件（part-r-00000和part-r-00001）分别记录不同条件的信息。**

**eclipse直接运行抛的异常：**

**（**

14/03/06 15:41:13 WARN mapred.LocalJobRunner: job\_local\_0001  
**j**ava.io.IOException: Illegal partition for 10.80.203.79 (1)  
at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(MapTask.java:1073)  
at org.apache.hadoop.mapred.MapTask$NewOutputCollector.write(MapTask.java:691)  
at org.apache.hadoop.mapreduce.TaskInputOutputContext.write(TaskInputOutputContext.java:80)  
at partition.FlowCount2$MyMapper.map(FlowCount2.java:120)  
at partition.FlowCount2$MyMapper.map(FlowCount2.java:1)  
at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:144)  
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:764)  
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:370)  
at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:214)  
14/03/06 15:41:14 INFO mapred.JobClient:  map 0% reduce 0%  
14/03/06 15:41:14 INFO mapred.JobClient: Job complete: job\_local\_0001  
14/03/06 15:41:14 INFO mapred.JobClient: Counters: 0

**）**

**记录超哥的总结：**

分区的例子必须打成jar运行
     * 用处：

*1.根据业务需要，产生多个输出文件
     * 2.多个reduce任务在运行，提高整体job的运行效率