大数据学习（八）：mapreduce编程案例-计算访问次数最多的5个网站
数据
2017/07/28 qq.com/a
2017/07/28 qq.com/bx
2017/07/28 qq.com/by
2017/07/28 qq.com/by3
2017/07/28 qq.com/news
2017/07/28 sina.com/news/socail
2017/07/28 163.com/ac
2017/07/28 sina.com/news/socail
2017/07/28 163.com/sport
2017/07/28 163.com/ac
2017/07/28 sina.com/play
2017/07/28 163.com/sport
2017/07/28 163.com/ac
2017/07/28 sina.com/movie
2017/07/28 sina.com/play
2017/07/28 sina.com/movie
2017/07/28 163.com/sport
2017/07/28 sina.com/movie
2017/07/28 163.com/ac
2017/07/28 163.com/ac
2017/07/28 163.com/acc
2017/07/28 qq.com/by
2017/07/28 qq.com/by3
2017/07/28 qq.com/news
2017/07/28 163.com/sport
2017/07/28 sina.com/news/socail
2017/07/28 163.com/sport
2017/07/28 sina.com/movie
2017/07/28 sina.com/news/socail
2017/07/28 sina.com/movie
2017/07/28 qq.com/news
2017/07/28 163.com/bb
2017/07/28 163.com/cc
2017/07/28 sina.com/lady/
2017/07/28 163.com/cc
2017/07/28 qq.com/news
2017/07/28 qq.com/by
2017/07/28 qq.com/by3
2017/07/28 sina.com/lady/
2017/07/28 qq.com/by3
2017/07/28 sina.com/lady/
2017/07/28 qq.com/by3
2017/07/28 qq.com/news
2017/07/28 qq.com/by3
2017/07/28 163.com/sport
2017/07/28 163.com/sport
2017/07/28 sina.com/news/socail
2017/07/28 sina.com/lady/
2017/07/28 sina.com/play
2017/07/28 sina.com/movie
2017/07/28 sina.com/music
2017/07/28 sina.com/sport
2017/07/28 sina.com/sport
2017/07/28 163.com/sport
2017/07/28 sina.com/news/socail
2017/07/28 sohu.com/lady/
2017/07/28 sohu.com/play
2017/07/28 sohu.com/movie
2017/07/28 sohu.com/music
2017/07/28 sohu.com/sport
2017/07/28 sohu.com/sport
2017/07/28 sina.com/news/socail
2017/07/28 baidu.com/lady/
2017/07/28 baidu.com/play
2017/07/28 baidu.com/movie
2017/07/28 baidu.com/music
2017/07/28 baidu.com/movie
2017/07/28 baidu.com/music
2017/07/28 baidu.com/movie
2017/07/28 baidu.com/music
2017/07/28 baidu.com/movie
2017/07/28 baidu.com/music
2017/07/28 baidu.com/movie
2017/07/28 baidu.com/music
2017/07/28 baidu.com/music
2017/07/28 baidu.com/movie
2017/07/28 baidu.com/music
2017/07/28 baidu.com/sport
2017/07/28 baidu.com/sport
package com.bigdata.mapreduce.topn;
/**
* 排序
* @author 90669
*
*/
public class PageCount implements Comparable<PageCount>{
private String page;
private int count;
public void set(String page,int count) {
this.page=page;
this.count=count;
}
public String getPage() {
return page;
}
public void setPage(String page) {
this.page = page;
}
public int getCount() {
return count;
}
public void setCount(int count) {
this.count = count;
}
@Override
public int compareTo(PageCount o) {
return o.getCount()-this.count==0?this.page.compareTo(o.getPage()):o.getCount()-this.count;
}
}
package com.bigdata.mapreduce.topn;
import java.io.IOException;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.TreeMap;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;
public class PageTopnReducer extends Reducer<Text, IntWritable, Text, IntWritable>{
Map<PageCount,Object> treeMap = new TreeMap<>();
@Override
protected void reduce(Text key, Iterable<IntWritable> values,
Reducer<Text, IntWritable, Text, IntWritable>.Context context) throws IOException, InterruptedException {
int count = 0;
for (IntWritable value : values) {
count += value.get();
}
PageCount pageCount = new PageCount();
pageCount.set(key.toString(), count);
treeMap.put(pageCount, null);
}
@Override
protected void cleanup(Context context)
throws IOException, InterruptedException {
Configuration conf = context.getConfiguration();
//int topn = conf.getInt("top.n", 5);
int topn = 5;
Set<Entry<PageCount, Object>> entrySet = treeMap.entrySet();
int i = 0;
for (Entry<PageCount, Object> entry : entrySet) {
context.write(new Text(entry.getKey().getPage()), new IntWritable(entry.getKey().getCount()));
i++;
if(i==topn)return;
}
}
}
package com.bigdata.mapreduce.topn;
import java.io.IOException;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;
public class PageTopnMapper extends Mapper<LongWritable, Text, Text, IntWritable>{
@Override
protected void map(LongWritable key, Text value, Mapper<LongWritable, Text, Text, IntWritable>.Context context)
throws IOException, InterruptedException {
String line = value.toString();
String[] split = line.split(" ");
context.write(new Text(split[1]), new IntWritable(1));
}
}
package com.bigdata.mapreduce.topn;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
public class JobSubmitter {
public static void main(String[] args) throws Exception {
/**
* 通过加载classpath下的*-site.xml文件解析参数
*/
Configuration conf = new Configuration();
conf.addResource("fs-site.xml");
Job job = Job.getInstance(conf);
job.setJarByClass(JobSubmitter.class);
job.setMapperClass(PageTopnMapper.class);
job.setReducerClass(PageTopnReducer.class);
job.setMapOutputKeyClass(Text.class);
job.setMapOutputValueClass(IntWritable.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
FileInputFormat.setInputPaths(job, new Path("D:\\mrdata\\url\\input"));
FileOutputFormat.setOutputPath(job, new Path("D:\\mrdata\\url\\output"));
job.waitForCompletion(true);
}
}
计算结果
163.com/sport 8
baidu.com/music 7
sina.com/news/socail 7
baidu.com/movie 6
qq.com/by3 6
sina.com/movie 6