3.4 Hadoop-MapReduce，模拟QQ好友推荐

叁歲伎倆 2022-05-24 06:11 180阅读 0赞

模拟QQ好友推荐，好友的好友，出现次数最多的推荐

第一行为QQ账号名，后面同排为自己好友

![20180522111811817][]

工程结构：

![20180522111817274][]

Mapper1：

<table style="table-layout:fixed;white-space:nowrap;width:0px;">    
 <tbody> 
  <tr style="height:95px;"> 
   <td style="color:rgb(57,57,57);border-color:rgb(167,167,167);white-space:pre-wrap;"> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">package com.test.friend;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import java.io.IOException;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.io.IntWritable;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.io.Text;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.mapreduce.Mapper;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.util.StringUtils;</span> 
    </div> 
    <div> 
     <br> 
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     <br> 
    </div> 
    <div> 
     <br> 
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    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">public class Mapper1 extends Mapper&lt;Text, Text, Text, IntWritable&gt;{ </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;/**</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; * 找到所有的fof：user1:user2 zs:ww ww:zs</span> 
    </div> 
    <div> 
     <br> 
    </div> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; */</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;protected void map(Text key, Text value,</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;Context context)</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;throws IOException, InterruptedException { </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; String user=key.toString();</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; String[] friends =StringUtils.split(value.toString(), '\t');</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; for (int i = 0; i &lt; friends.length; i++) { </span> 
    </div> 
    <div> 
     <br> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;String f1 = friends[i];</span> 
    </div> 
    <div> 
     <br> 
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    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;String userAndFriend= f1.compareTo(user)&gt;0 ?f1+":"+user:user+":"+f1;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;context.write(new Text(userAndFriend), new IntWritable(0)); //输出的是直接好友关系 比如：zs:ls 0</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;for (int j = i+1; j &lt; friends.length; j++) { </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; String f2 = friends[j];</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; String fof= f1.compareTo(f2)&gt;0 ?f1+":"+f2:f2+":"+f1;</span> 
    </div> 
    <div> 
     <br> 
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    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; context.write(new Text(fof), new IntWritable(1));//输出的是间接好友关系 比如：zs:ls 1</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;}</span> 
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     <br> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; }</span> 
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    <div> 
     <br> 
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    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; </span> 
    </div> 
    <div> 
     <br> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;}</span> 
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     <br> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">}</span> 
    </div></td> 
  </tr> 
 </tbody> 
</table>

Reducer1：

<table style="table-layout:fixed;white-space:nowrap;width:0px;">    
 <tbody> 
  <tr style="height:163px;"> 
   <td style="color:rgb(57,57,57);border-color:rgb(167,167,167);white-space:pre-wrap;"> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">package com.test.friend;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import java.io.IOException;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
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     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.io.IntWritable;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.io.Text;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.mapreduce.Reducer;</span> 
    </div> 
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     <br> 
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    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">public class Reducer1 extends Reducer&lt;Text, IntWritable, Text, IntWritable&gt;{ </span> 
    </div> 
    <div> 
     <br> 
    </div> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;protected void reduce(Text arg0, Iterable&lt;IntWritable&gt; arg1,</span> 
    </div> 
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     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;Context arg2)</span> 
    </div> 
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     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;throws IOException, InterruptedException { </span> 
    </div> 
    <div> 
     <br> 
    </div> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; int sum =0;</span> 
    </div> 
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     <br> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; boolean f=true;</span> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; for(IntWritable i :arg1){ </span> 
    </div> 
    <div> 
     <br> 
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    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;if(i.get()==0){//如果存在一个value=0的情况。一定在map时候有直接好友存在。删除这一组（不要）</span> 
    </div> 
    <div> 
     <br> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; f=false;</span> 
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    <div> 
     <br> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; break;</span> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;}else{ </span> 
    </div> 
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     <br> 
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    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; sum=sum+i.get();</span> 
    </div> 
    <div> 
     <br> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;}</span> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; }</span> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; if(f){ </span> 
    </div> 
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     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;arg2.write(arg0, new IntWritable(sum));</span> 
    </div> 
    <div> 
     <br> 
    </div> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; }</span> 
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     <br> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;}</span> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">}</span> 
    </div></td> 
  </tr> 
 </tbody> 
</table>

Mapper2：

<table style="table-layout:fixed;white-space:nowrap;width:0px;">    
 <tbody> 
  <tr style="height:88px;"> 
   <td style="color:rgb(57,57,57);border-color:rgb(167,167,167);white-space:pre-wrap;"> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">package com.test.friend;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import java.io.IOException;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
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     <br> 
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    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.io.Text;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.mapreduce.Mapper;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">public class Mapper2 extends Mapper&lt;Text, Text, User, Text&gt;{ </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;protected void map(Text key, Text value,</span> 
    </div> 
    <div> 
     <br> 
    </div> 
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     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;Context context)</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; &nbsp;throws IOException, InterruptedException { </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; String f1 =key.toString().split(":")[0];</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; String f2 =key.toString().split(":")[1];</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; int count =Integer.parseInt(value.toString());</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; User u1 =new User();</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; u1.setUser(f1);</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; u1.setOther(f2);</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; u1.setCount(count);</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; context.write(u1, new Text(f2+":"+count));</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; User u2 =new User();</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; u2.setUser(f2);</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; u2.setOther(f1);</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; u2.setCount(count);</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; context.write(u2, new Text(f1+":"+count));</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;}</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">}</span> 
    </div></td> 
  </tr> 
 </tbody> 
</table>

Reducer2：

<table style="table-layout:fixed;white-space:nowrap;width:0px;">    
 <tbody> 
  <tr style="height:86px;"> 
   <td style="color:rgb(57,57,57);border-color:rgb(167,167,167);white-space:pre-wrap;"> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">package com.test.friend;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import java.io.IOException;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.io.Text;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.mapreduce.Reducer;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">public class Reducer2 extends Reducer&lt;User, Text, Text, Text&gt;{ </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;protected void reduce(User arg0, Iterable&lt;Text&gt; arg1,</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;Context arg2)</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; &nbsp;throws IOException, InterruptedException { </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; StringBuilder sb =new StringBuilder();</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; for(Text t:arg1){ </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;sb.append(t.toString()).append(",");</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; }</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; arg2.write(new Text(arg0.getUser()), new Text(sb.substring(0, sb.length()-1)));</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;}</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">}</span> 
    </div></td> 
  </tr> 
 </tbody> 
</table>

User：

<table style="table-layout:fixed;white-space:nowrap;width:0px;">    
 <tbody> 
  <tr style="height:79px;"> 
   <td style="color:rgb(57,57,57);border-color:rgb(167,167,167);white-space:pre-wrap;"> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">package com.test.friend;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import java.io.DataInput;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import java.io.DataOutput;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import java.io.IOException;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.io.WritableComparable;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">public class User implements WritableComparable&lt;User&gt; { </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;private String user;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;private String other;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;private int count;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;public String getUser() { </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; return user;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;}</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;public void setUser(String user) { </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; this.user = user;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;}</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;public String getOther() { </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; return other;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;}</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;public void setOther(String other) { </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; this.other = other;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;}</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;public int getCount() { </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; return count;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;}</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;public void setCount(int count) { </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; this.count = count;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;}</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;public void write(DataOutput out) throws IOException { </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; out.writeUTF(user);</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; out.writeUTF(other);</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; out.writeInt(count);</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;}</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;public void readFields(DataInput in) throws IOException { </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; this.user =in.readUTF();</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; this.other =in.readUTF();</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; this.count=in.readInt();</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;}</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;public int compareTo(User o) { </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; int r = this.getUser().compareTo(o.getUser());</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; if(r==0){ </span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;return -Integer.compare(this.getCount(), o.getCount());</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; }</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; return r;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;}</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">}</span> 
    </div></td> 
  </tr> 
 </tbody> 
</table>

Group：

<table style="table-layout:fixed;white-space:nowrap;width:0px;">    
 <tbody> 
  <tr style="height:97px;"> 
   <td style="color:rgb(57,57,57);border-color:rgb(167,167,167);white-space:pre-wrap;"> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">package com.test.friend;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.io.WritableComparable;</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.io.WritableComparator;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">public class Group extends WritableComparator{ </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;public Group(){ </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; super(User.class,true);</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;}</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;public int compare(WritableComparable a, WritableComparable b) { </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; User u1 =(User) a;</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; User u2=(User) b;</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; return u1.getUser().compareTo(u2.getUser());</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;}</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">}</span> 
    </div></td> 
  </tr> 
 </tbody> 
</table>

RunJob：

<table style="table-layout:fixed;white-space:nowrap;width:0px;">    
 <tbody> 
  <tr style="height:65px;"> 
   <td style="color:rgb(57,57,57);border-color:rgb(167,167,167);white-space:pre-wrap;"> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">package com.test.friend;</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.conf.Configuration;</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.fs.FileSystem;</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.fs.Path;</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.io.IntWritable;</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.io.Text;</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.mapreduce.Job;</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.mapreduce.lib.input.KeyValueTextInputFormat;</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">/**</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;* 模拟QQ好友推荐</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;* @author root</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;*/</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">public class RunJob { </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;public static void main(String[] args) { </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; Configuration config =new Configuration();</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; config.set("fs.defaultFS", "hdfs://node1:9000");</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">// config.set("mapred.jar", "C:\\Users\\Administrator\\Desktop\\wc.jar");</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; config.set("mapreduce.input.keyvaluelinerecordreader.key.value.separator", "\t");//设置为制表符拆分</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; try { </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;FileSystem fs =FileSystem.get(config);</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;Job job =Job.getInstance(config);</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;job.setJobName("f1");</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;job.setJarByClass(RunJob.class);//job的入口类</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;job.setMapperClass(Mapper1.class);</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;job.setReducerClass(Reducer1.class);</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;"> </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;job.setMapOutputKeyClass(Text.class);</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;job.setMapOutputValueClass(IntWritable.class);</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;//设置一个map任务输入数据的格式 &nbsp;KeyValueTextInputFormat 把第一个隔开符的左边为key，右边为value</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;job.setInputFormatClass(KeyValueTextInputFormat.class);</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;//定义job任务输入数据目录和输出结果目录</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;//把friend上传到hdfs目录中/usr/intput/friend</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;//输出结果数据放到/usr/output/f1</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;FileInputFormat.addInputPath(job, new Path("/usr/input/friend"));</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;//输出结果数据目录不能存在，job执行时自动创建的。如果在执行时目录已经存在，则job执行失败。</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;Path output =new Path("/usr/output/f1");</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;if(fs.exists(output)){ </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; fs.delete(output, true);</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;}</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;FileOutputFormat.setOutputPath(job,output );</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;boolean f= job.waitForCompletion(true);</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;if(f){ </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; System.out.println("第一个job执行成功！");</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; job =Job.getInstance(config);</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; job.setJobName("f2");</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; job.setJarByClass(RunJob.class);//job的入口类</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; job.setMapperClass(Mapper2.class);</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; job.setReducerClass(Reducer2.class);</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;"> </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; job.setMapOutputKeyClass(User.class);</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; job.setMapOutputValueClass(Text.class);</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; job.setGroupingComparatorClass(Group.class);</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; job.setInputFormatClass(KeyValueTextInputFormat.class);//KeyValueTextInputFormat 把第一个隔开符的左边为key，右边为value</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; //定义job任务输入数据目录和输出结果目录</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; //获取到hdfs目录中/usr/intput/f1</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; //输出结果数据放到/usr/output/f2</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; FileInputFormat.addInputPath(job, new Path("/usr/output/f1"));</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; //输出结果数据目录不能存在，job执行时自动创建的。如果在执行时目录已经存在，则job执行失败。</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; output =new Path("/usr/output/f2");</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; if(fs.exists(output)){ </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; &nbsp;fs.delete(output, true);</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; }</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; FileOutputFormat.setOutputPath(job,output );</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; f= job.waitForCompletion(true);</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; if(f){ </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; &nbsp;System.out.println("第二个job执行成功！");</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp; }</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;}</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; } catch (Exception e) { </span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;// TODO Auto-generated catch block</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; &nbsp;e.printStackTrace();</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp; }</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">&nbsp;}</span> 
    </div> 
    <div> 
     <span style="font-family:'Microsoft YaHei', STXihei;color:rgb(0,0,0);background-color:transparent;">}</span> 
    </div></td> 
  </tr> 
 </tbody> 
</table>

[20180522111811817]: /images/20220524/b089645918a141a787c15b2d95ec4fa7.png
[20180522111817274]: /images/20220524/e9abec437aed435ea594794485ecdba3.png