MapReduce(四)--MapReduce案例

一、倒排索引案例（多job串联）

1.1、需求及分析

1.2、代码编写

1.2.1、第一次处理

1）第一次处理，编写OneIndexMapper类

package com.dianchou.mr.index;

import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.lib.input.FileSplit;

import java.io.IOException;

public class OneIndexMapper extends Mapper<LongWritable, Text, Text, IntWritable> {

    Text k = new Text();
    IntWritable v = new IntWritable(1);
    String name;

    @Override
    protected void setup(Context context) throws IOException, InterruptedException {
        FileSplit split = (FileSplit) context.getInputSplit();
        name = split.getPath().getName();
    }

    @Override
    protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
        String line = value.toString();
        String[] words = line.split(" ");
        for (String word : words) {
            k.set(word + "---" + name);
            context.write(k,v);
        }
    }
}

2）第一次处理，编写OneIndexReducer类

package com.dianchou.mr.index;

import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

import java.io.IOException;


public class OneIndexReducer extends Reducer<Text, IntWritable,Text,IntWritable> {
    //atguigu--a.txt	3

    IntWritable v = new IntWritable();
    @Override
    protected void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException {
        int sum = 0;
        for (IntWritable value : values) {
            sum += value.get();
        }
        v.set(sum);
        context.write(key, v);

    }
}

3）第一次处理，编写OneIndexDriver类

package com.dianchou.mr.index;

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 OneIndexDriver {

    public static void main(String[] args) throws Exception {

        // 输入输出路径需要根据自己电脑上实际的输入输出路径设置
        args = new String[] { "D:\hadoop\index-input", "D:\hadoop\index-output" };

        Configuration conf = new Configuration();

        Job job = Job.getInstance(conf);
        job.setJarByClass(OneIndexDriver.class);

        job.setMapperClass(OneIndexMapper.class);
        job.setReducerClass(OneIndexReducer.class);

        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(IntWritable.class);

        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);

        FileInputFormat.setInputPaths(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));

        job.waitForCompletion(true);
    }
}

4）查看第一次输出结果

atguigu--a.txt	3
atguigu--b.txt	2
atguigu--c.txt	2
pingping--a.txt	1
pingping--b.txt	3
pingping--c.txt	1
ss--a.txt	2
ss--b.txt	1
ss--c.txt	1

1.1.2、第二次处理

1）第二次处理，编写TwoIndexMapper类

package com.dianchou.mr.index;

import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;

import java.io.IOException;

public class TwoIndexMapper extends Mapper<LongWritable, Text,Text,Text> {

    Text k = new Text();
    Text v = new Text();

    @Override
    protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
        //atguigu---a.txt	3  ==>atguigu   a.txt	3
        String line = value.toString();
        String[] fields = line.split("---");
        k.set(fields[0]);
        v.set(fields[1]);
        context.write(k, v);

    }
}

2）第二次处理，编写TwoIndexReducer类

package com.dianchou.mr.index;

import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

import java.io.IOException;

public class TwoIndexReducer extends Reducer<Text,Text,Text,Text> {
    Text v = new Text();

    @Override
    protected void reduce(Text key, Iterable<Text> values, Context context) throws IOException, InterruptedException {
        // atguigu a.txt 3
        // atguigu b.txt 2
        // atguigu c.txt 2
        // atguigu c.txt-->2 b.txt-->2 a.txt-->3

        StringBuilder sb = new StringBuilder();
        for (Text value : values) {
            sb.append(value.toString().replace("	", "-->") + "	");
        }
        v.set(sb.toString());
        context.write(key, v);
    }
}

3）第二次处理，编写TwoIndexDriver类

package com.dianchou.mr.index;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
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 TwoIndexDriver {

    public static void main(String[] args) throws Exception {

        // 输入输出路径需要根据自己电脑上实际的输入输出路径设置
        args = new String[] { "D:\hadoop\index-output", "D:\hadoop\index-output2" };

        Configuration config = new Configuration();
        Job job = Job.getInstance(config);

        job.setJarByClass(TwoIndexDriver.class);
        job.setMapperClass(TwoIndexMapper.class);
        job.setReducerClass(TwoIndexReducer.class);

        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(Text.class);

        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(Text.class);

        FileInputFormat.setInputPaths(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));

        boolean result = job.waitForCompletion(true);
        System.exit(result?0:1);
    }
}

4）第二次查看最终结果

atguigu	c.txt-->2	b.txt-->2	a.txt-->3
pingping	c.txt-->1	b.txt-->3	a.txt-->1
ss	c.txt-->1	b.txt-->1	a.txt-->2

二、TopN案例

2.1、需求及分析

2.2、代码实现

1）编写FlowBean类

package com.dianchou.mr.top;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import org.apache.hadoop.io.WritableComparable;

public class FlowBean implements WritableComparable<FlowBean>{

    private long upFlow;
    private long downFlow;
    private long sumFlow;

    public FlowBean() {
        super();
    }

    public FlowBean(long upFlow, long downFlow) {
        super();
        this.upFlow = upFlow;
        this.downFlow = downFlow;
    }

    @Override
    public void write(DataOutput out) throws IOException {
        out.writeLong(upFlow);
        out.writeLong(downFlow);
        out.writeLong(sumFlow);
    }

    @Override
    public void readFields(DataInput in) throws IOException {
        upFlow = in.readLong();
        downFlow = in.readLong();
        sumFlow = in.readLong();
    }

    public long getUpFlow() {
        return upFlow;
    }

    public void setUpFlow(long upFlow) {
        this.upFlow = upFlow;
    }

    public long getDownFlow() {
        return downFlow;
    }

    public void setDownFlow(long downFlow) {
        this.downFlow = downFlow;
    }

    public long getSumFlow() {
        return sumFlow;
    }

    public void setSumFlow(long sumFlow) {
        this.sumFlow = sumFlow;
    }

    @Override
    public String toString() {
        return upFlow + "	" + downFlow + "	" + sumFlow;
    }

    public void set(long downFlow2, long upFlow2) {
        downFlow = downFlow2;
        upFlow = upFlow2;
        sumFlow = downFlow2 + upFlow2;
    }

    @Override
    public int compareTo(FlowBean bean) {
        int result;
        if (this.sumFlow > bean.getSumFlow()) {
            result = -1;
        }else if (this.sumFlow < bean.getSumFlow()) {
            result = 1;
        }else {
            result = 0;
        }
        return result;
    }
}

2）编写TopNMapper类

package com.dianchou.mr.top;

import java.io.IOException;
import java.util.Iterator;
import java.util.TreeMap;

import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;

public class TopNMapper extends Mapper<LongWritable, Text, FlowBean, Text> {

    // 定义一个TreeMap作为存储数据的容器（天然按key排序）
    private TreeMap<FlowBean, Text> flowMap = new TreeMap<FlowBean, Text>();
    private FlowBean kBean;

    @Override
    protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {

        kBean = new FlowBean();
        Text v = new Text();

        // 1 获取一行
        String line = value.toString();

        // 2 切割
        String[] fields = line.split("	");

        // 3 封装数据
        String phoneNum = fields[0];
        long upFlow = Long.parseLong(fields[1]);
        long downFlow = Long.parseLong(fields[2]);
        long sumFlow = Long.parseLong(fields[3]);

        kBean.setDownFlow(downFlow);
        kBean.setUpFlow(upFlow);
        kBean.setSumFlow(sumFlow);

        v.set(phoneNum);

        // 4 向TreeMap中添加数据
        flowMap.put(kBean, v);

        // 5 限制TreeMap的数据量，超过10条就删除掉流量最小的一条数据
        if (flowMap.size() > 10) {
            flowMap.remove(flowMap.lastKey());
        }
    }

    @Override
    protected void cleanup(Context context) throws IOException, InterruptedException {
        // 6 遍历treeMap集合，输出数据
        Iterator<FlowBean> bean = flowMap.keySet().iterator();
        while (bean.hasNext()) {
            FlowBean k = bean.next();
            context.write(k, flowMap.get(k));
        }
    }
}

3）编写TopNReducer类

package com.dianchou.mr.top;

import java.io.IOException;
import java.util.Iterator;
import java.util.TreeMap;

import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

public class TopNReducer extends Reducer<FlowBean, Text, Text, FlowBean> {

    // 定义一个TreeMap作为存储数据的容器（天然按key排序）
    TreeMap<FlowBean, Text> flowMap = new TreeMap<FlowBean, Text>();

    @Override
    protected void reduce(FlowBean key, Iterable<Text> values, Context context) throws IOException, InterruptedException {

        for (Text value : values) {
            FlowBean bean = new FlowBean();
            bean.set(key.getDownFlow(), key.getUpFlow());

            // 1 向treeMap集合中添加数据
            flowMap.put(bean, new Text(value));

            // 2 限制TreeMap数据量，超过10条就删除掉流量最小的一条数据
            if (flowMap.size() > 10) {
                flowMap.remove(flowMap.lastKey());
            }
        }
    }

    @Override
    protected void cleanup(Reducer<FlowBean, Text, Text, FlowBean>.Context context) throws IOException, InterruptedException {
        // 3 遍历集合，输出数据
        Iterator<FlowBean> it = flowMap.keySet().iterator();
        while (it.hasNext()) {
            FlowBean v = it.next();
            context.write(new Text(flowMap.get(v)), v);
        }
    }
}

4）编写TopNDriver类

package com.dianchou.mr.top;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
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 TopNDriver {

    public static void main(String[] args) throws Exception {

        args  = new String[]{"D:\hadoop\top-input","D:\hadoop\top-output"};

        // 1 获取配置信息，或者job对象实例
        Configuration configuration = new Configuration();
        Job job = Job.getInstance(configuration);

        // 6 指定本程序的jar包所在的本地路径
        job.setJarByClass(TopNDriver.class);

        // 2 指定本业务job要使用的mapper/Reducer业务类
        job.setMapperClass(TopNMapper.class);
        job.setReducerClass(TopNReducer.class);

        // 3 指定mapper输出数据的kv类型
        job.setMapOutputKeyClass(FlowBean.class);
        job.setMapOutputValueClass(Text.class);

        // 4 指定最终输出的数据的kv类型
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(FlowBean.class);

        // 5 指定job的输入原始文件所在目录
        FileInputFormat.setInputPaths(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));

        // 7 将job中配置的相关参数，以及job所用的java类所在的jar包， 提交给yarn去运行
        boolean result = job.waitForCompletion(true);
        System.exit(result ? 0 : 1);
    }
}

三、共同好友案例

3.1、需求及分析

好友列表数据，冒号前是一个用户，冒号后是该用户的所有好友（数据中的好友关系是单向的），求出哪些人两两之间有共同好友，及他俩的共同好友都有谁？

数据输入：

A:B,C,D,F,E,O
B:A,C,E,K
C:F,A,D,I
D:A,E,F,L
E:B,C,D,M,L
F:A,B,C,D,E,O,M
G:A,C,D,E,F
H:A,C,D,E,O
I:A,O
J:B,O
K:A,C,D
L:D,E,F
M:E,F,G
O:A,H,I,J

需求分析：

先求出A、B、C、….等是谁的好友

第一次输出结果：

A	I,K,C,B,G,F,H,O,D,
B	A,F,J,E,
C	A,E,B,H,F,G,K,
D	G,C,K,A,L,F,E,H,
E	G,M,L,H,A,F,B,D,
F	L,M,D,C,G,A,
G	M,
H	O,
I	O,C,
J	O,
K	B,
L	D,E,
M	E,F,
O	A,H,I,J,F,

第二次输出结果：

A-B	E C
A-C	D F
A-D	E F
A-E	D B C
A-F	O B C D E
A-G	F E C D
A-H	E C D O
A-I	O
A-J	O B
A-K	D C
A-L	F E D
A-M	E F
B-C	A
B-D	A E
B-E	C
B-F	E A C
B-G	C E A
B-H	A E C
B-I	A
B-K	C A
B-L	E
B-M	E
B-O	A
C-D	A F
C-E	D
C-F	D A
C-G	D F A
C-H	D A
C-I	A
C-K	A D
C-L	D F
C-M	F
C-O	I A
D-E	L
D-F	A E
D-G	E A F
D-H	A E
D-I	A
D-K	A
D-L	E F
D-M	F E
D-O	A
E-F	D M C B
E-G	C D
E-H	C D
E-J	B
E-K	C D
E-L	D
F-G	D C A E
F-H	A D O E C
F-I	O A
F-J	B O
F-K	D C A
F-L	E D
F-M	E
F-O	A
G-H	D C E A
G-I	A
G-K	D A C
G-L	D F E
G-M	E F
G-O	A
H-I	O A
H-J	O
H-K	A C D
H-L	D E
H-M	E
H-O	A
I-J	O
I-K	A
I-O	A
K-L	D
K-O	A
L-M	E F

3.2、代码编写

1）第一次Mapper类

package com.dianchou.mr.friends;

import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;

import java.io.IOException;

public class OneShareFriendsMapper extends Mapper<LongWritable, Text, Text, Text> {

    @Override
    protected void map(LongWritable key, Text value, Mapper<LongWritable, Text, Text, Text>.Context context)
            throws IOException, InterruptedException {

        // 1 获取一行 A:B,C,D,F,E,O
        String line = value.toString();
        //读取到最后
        if ("".equals(line)) {
            return;
        }

        // 2 切割
        String[] fields = line.split(":");

        // 3 获取person和好友
        String person = fields[0];
        String[] friends = fields[1].split(",");

        // 4写出去
        for (String friend : friends) {
            // 输出 <好友，人>
            context.write(new Text(friend), new Text(person));
        }
    }
}

2）第一次Reducer类

package com.dianchou.mr.friends;

import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

import java.io.IOException;

public class OneShareFriendsReducer extends Reducer<Text, Text, Text, Text> {

    @Override
    protected void reduce(Text key, Iterable<Text> values, Context context)throws IOException, InterruptedException {
        StringBuffer sb = new StringBuffer();
        //1 拼接
        for(Text person: values){
            sb.append(person).append(",");
        }
        //2 写出
        context.write(key, new Text(sb.toString()));
    }
}

3）第一次Driver类

package com.dianchou.mr.friends;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
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 OneShareFriendsDriver {

    public static void main(String[] args) throws Exception {
        args = new String[]{"D:\hadoop\friends-input","D:\hadoop\friends-output"};

        // 1 获取job对象
        Configuration configuration = new Configuration();
        Job job = Job.getInstance(configuration);

        // 2 指定jar包运行的路径
        job.setJarByClass(OneShareFriendsDriver.class);

        // 3 指定map/reduce使用的类
        job.setMapperClass(OneShareFriendsMapper.class);
        job.setReducerClass(OneShareFriendsReducer.class);

        // 4 指定map输出的数据类型
        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(Text.class);

        // 5 指定最终输出的数据类型
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(Text.class);

        // 6 指定job的输入原始所在目录
        FileInputFormat.setInputPaths(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));

        // 7 提交
        boolean result = job.waitForCompletion(true);

        System.exit(result?0:1);
    }
}

4）第二次Mapper类

package com.dianchou.mr.friends;

import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;

import java.io.IOException;
import java.util.Arrays;

public class TwoShareFriendsMapper extends Mapper<LongWritable, Text, Text, Text> {

    @Override
    protected void map(LongWritable key, Text value, Context context)
            throws IOException, InterruptedException {

        // A I,K,C,B,G,F,H,O,D,
        // 友 人，人，人
        String line = value.toString();
        String[] friend_persons = line.split("	");

        String friend = friend_persons[0];
        String[] persons = friend_persons[1].split(",");

        Arrays.sort(persons);

        for (int i = 0; i < persons.length - 1; i++) {

            for (int j = i + 1; j < persons.length; j++) {
                // 发出 <人-人，好友> ，这样，相同的“人-人”对的所有好友就会到同1个reduce中去
                context.write(new Text(persons[i] + "-" + persons[j]), new Text(friend));
            }
        }
    }
}

5）第二次Reducer类

package com.dianchou.mr.friends;

import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

import java.io.IOException;

public class TwoShareFriendsReducer extends Reducer<Text, Text, Text, Text> {

    @Override
    protected void reduce(Text key, Iterable<Text> values, Context context)	throws IOException, InterruptedException {

        StringBuffer sb = new StringBuffer();

        for (Text friend : values) {
            sb.append(friend).append(" ");
        }

        context.write(key, new Text(sb.toString()));
    }
}

6）第二次Driver类

package com.dianchou.mr.friends;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
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 TwoShareFriendsDriver {

    public static void main(String[] args) throws Exception {

        args = new String[]{"D:\hadoop\friends-output","D:\hadoop\friends-output2"};

        // 1 获取job对象
        Configuration configuration = new Configuration();
        Job job = Job.getInstance(configuration);

        // 2 指定jar包运行的路径
        job.setJarByClass(TwoShareFriendsDriver.class);

        // 3 指定map/reduce使用的类
        job.setMapperClass(TwoShareFriendsMapper.class);
        job.setReducerClass(TwoShareFriendsReducer.class);

        // 4 指定map输出的数据类型
        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(Text.class);

        // 5 指定最终输出的数据类型
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(Text.class);

        // 6 指定job的输入原始所在目录
        FileInputFormat.setInputPaths(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));

        // 7 提交
        boolean result = job.waitForCompletion(true);
        System.exit(result?0:1);
    }
}