mr利用mapjoin计算出每个部门的总工资以及部门名称

短命女 2022-04-25 08:44 242阅读 0赞

> 把作业素材dept.txt（部门表） 和 emp.txt（员工表）导入hadoop中  
> 求各个部门的总工资(可以使用map side join 或者 reduce side join)  
> 结果如下:  
> ACCOUNTING 8750  
> RESEARCH 6775  
> SALES 9400

> **dept.txt数据**  
> 10,ACCOUNTING,NEW YORK  
> 20,RESEARCH,DALLAS  
> 30,SALES,CHICAGO  
> 40,OPERATIONS,BOSTON

> **emp.txt数据**  
> 7369,SMITH,CLERK,7902,17-12月-80,800,20  
> 7499,ALLEN,SALESMAN,7698,20-2月-81,1600,300,30  
> 7521,WARD,SALESMAN,7698,22-2月-81,1250,500,30  
> 7566,JONES,MANAGER,7839,02-4月-81,2975,20  
> 7654,MARTIN,SALESMAN,7698,28-9月-81,1250,1400,30  
> 7698,BLAKE,MANAGER,7839,01-5月-81,2850,30  
> 7782,CLARK,MANAGER,7839,09-6月-81,2450,10  
> 7839,KING,PRESIDENT,17-11月-81,5000,10  
> 7844,TURNER,SALESMAN,7698,08-9月-81,1500,0,30  
> 7900,JAMES,CLERK,7698,03-12月-81,950,30  
> 7902,FORD,ANALYST,7566,03-12月-81,3000,20  
> 7934,MILLER,CLERK,7782,23-1月-82,1300,10

package com.bw.project;
    
    import java.io.BufferedReader;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.InputStreamReader;
    import java.net.URI;
    import java.util.Collection;
    import java.util.HashMap;
    import java.util.Map;
    
    import org.apache.hadoop.conf.Configuration;
    import org.apache.hadoop.fs.FileSystem;
    import org.apache.hadoop.fs.Path;
    import org.apache.hadoop.io.IntWritable;
    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.lib.input.FileInputFormat;
    import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
    
    
    
    public class MR {
    	public static class DMapper extends Mapper<LongWritable, Text, Text, IntWritable>{
    		Map<String, String> map = new HashMap<>();
    		@Override
    		protected void setup(Mapper<LongWritable, Text, Text, IntWritable>.Context context)
    				throws IOException, InterruptedException {
    			FileSystem fs=FileSystem.getLocal(context.getConfiguration());
    			Path[] paths = context.getLocalCacheFiles();
    			InputStream in = fs.open(paths[0]);
    			BufferedReader bf=new BufferedReader(new InputStreamReader(in));
    			String read="";
    			while ((read=bf.readLine())!=null) {
    				String[] split = read.split(",");
    				//context.write(new Text(split[0]), new Text("t1:"+split[1]));
    				map.put(split[0], split[1]);
    			}
    			
    			bf.close();
    			in.close();
    			fs.close();
    		}
    		
    		@Override
    		protected void map(LongWritable key, Text value, Mapper<LongWritable, Text, Text, IntWritable>.Context context)
    				throws IOException, InterruptedException {
    			String[] split = value.toString().split(",");
    			if ((map.get(split[7]))!=null) {
    				String dname=map.get(split[7]);
    				String dwString=dname+":"+split[5];
    				map.put(split[7], dwString);
    			}
    		}
    		@Override
    		protected void cleanup(Mapper<LongWritable, Text, Text, IntWritable>.Context context)
    				throws IOException, InterruptedException {
    			Collection<String> values = map.values();
    			for (String s : values) {
    				int sum=0;
    				String[] split = s.split(":");
    				for (int i = 1; i < split.length; i++) {
    					sum+=Integer.parseInt(split[i]);
    				}
    				if (sum>0) {
    					context.write(new Text(split[0]), new IntWritable(sum));
    				}
    			}
    		}
    	}
    	
    	public static void main(String[] args) throws Exception {
    		Configuration conf = new Configuration();
    		Job job = Job.getInstance(conf);
    		job.setJarByClass(Demo.class);
    		job.addCacheFile(new URI("dept.txt"));
    		
    		job.setMapperClass(DMapper.class);
    		job.setMapOutputKeyClass(Text.class);
    		job.setMapOutputValueClass(Text.class);
    		
    		job.setNumReduceTasks(0);
    		/*job.setReducerClass(DReduce.class);
    		job.setOutputKeyClass(Text.class);
    		job.setOutputValueClass(IntWritable.class);*/
    		
    		FileInputFormat.addInputPath(job,new Path("emp.txt"));
    		FileOutputFormat.setOutputPath(job, new Path("dept1"));
    		
    		job.waitForCompletion(true);
    	}
    	
    	
    }