Hadoop-MapReduce应用案例

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环境

  • CentOS 6.8 64位 1核 2GB

  • JDK 1.7.0_55 64 位

  • Hadoop 1.1.2

准备测试数据

  • 创建部门文件 dept,内容如下
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10,DEVELOP,BEIJING
20,UI,SHANGHAI
30,TEST,GUANGZHOU
40,OPS,SHENZHEN
  • 创建员工文件 emp,内容如下
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7369,SMITH,PRIMARY,7902,17-12月-80,10500,,20
7499,ALLEN,SENIOR,7698,20-2月-81,15500,300,30
7521,WARD,SENIOR,7698,22-2月-81,17500,500,30
7566,JONES,MANAGER,7839,02-4月-81,20500,,20
7654,MARTIN,SENIOR,7698,28-9月-81,16500,1400,30
7698,BLAKE,MANAGER,7839,01-5月-81,21000,,30
7782,CLARK,MANAGER,7839,09-6月-81,20000,,10
7839,KING,SENIOR,,17-11月-81,14500,,10
7844,TURNER,SENIOR,7698,08-9月-81,19500,0,30
7900,JAMES,PRIMARY,7698,03-12月-81,10000,,30
7902,FORD,SENIOR,7566,03-12月-81,19000,,20
7934,MILLER,PRIMARY,7782,23-1月-82,9500,,10
  • 在 HDFS 创建 /class6/input 目录
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$ hadoop fs -mkdir -p /class6/input
  • 把 dept、emp 上传到 HDFS 中 /class6/input 目录中
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$ hadoop fs -copyFromLocal dept /class6/input
$ hadoop fs -copyFromLocal emp /class6/input
  • 在HDFS中查看 /class6/input 目录
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$ hadoop fs -ls /class6/input
Found 2 items
-rw-r--r-- 1 yohann supergroup 80 2021-05-15 22:39 /class6/input/dept
-rw-r--r-- 1 yohann supergroup 538 2021-05-15 22:39 /class6/input/emp
  • 创建 /app/hadoop-1.1.2/myclass/class6 目录并进入
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$ cd /app/hadoop-1.1.2/myclass
$ mkdir class6
$ cd class6

求各个部门的总工资

  • 创建 Q1SumDeptSalary.java,代码如下
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import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.filecache.DistributedCache;
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.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;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

public class Q1SumDeptSalary extends Configured implements Tool {

public static class MapClass extends Mapper<LongWritable, Text, Text, Text> {

private Map<String, String> deptMap = new HashMap<String, String>();
private String[] kv;

@Override
protected void setup(Context context) throws IOException, InterruptedException {
BufferedReader in = null;
try {

Path[] paths = DistributedCache.getLocalCacheFiles(context.getConfiguration());
String deptIdName = null;
for (Path path : paths) {

if (path.toString().contains("dept")) {
in = new BufferedReader(new FileReader(path.toString()));
while (null != (deptIdName = in.readLine())) {

deptMap.put(deptIdName.split(",")[0], deptIdName.split(",")[1]);
}
}
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (in != null) {
in.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}

public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {

kv = value.toString().split(",");

if (deptMap.containsKey(kv[7])) {
if (null != kv[5] && !"".equals(kv[5].toString())) {
context.write(new Text(deptMap.get(kv[7].trim())), new Text(kv[5].trim()));
}
}
}
}

public static class Reduce extends Reducer<Text, Text, Text, LongWritable> {

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

long sumSalary = 0;
for (Text val : values) {
sumSalary += Long.parseLong(val.toString());
}

context.write(key, new LongWritable(sumSalary));
}
}

@Override
public int run(String[] args) throws Exception {

Job job = new Job(getConf(), "Q1SumDeptSalary");
job.setJobName("Q1SumDeptSalary");
job.setJarByClass(Q1SumDeptSalary.class);
job.setMapperClass(MapClass.class);
job.setReducerClass(Reduce.class);

job.setInputFormatClass(TextInputFormat.class);

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

String[] otherArgs = new GenericOptionsParser(job.getConfiguration(), args).getRemainingArgs();
DistributedCache.addCacheFile(new Path(otherArgs[0]).toUri(), job.getConfiguration());
FileInputFormat.addInputPath(job, new Path(otherArgs[1]));
FileOutputFormat.setOutputPath(job, new Path(otherArgs[2]));

job.waitForCompletion(true);
return job.isSuccessful() ? 0 : 1;
}

public static void main(String[] args) throws Exception {
int res = ToolRunner.run(new Configuration(), new Q1SumDeptSalary(), args);
System.exit(res);
}
}
  • 编译打包
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$ javac -classpath ../../hadoop-core-1.1.2.jar:../../lib/commons-cli-1.2.jar Q1SumDeptSalary.java
$ jar cvf ./Q1SumDeptSalary.jar ./Q1SumDept*.class
$ mv *.jar /app/hadoop-1.1.2/
$ rm Q1SumDept*.class
  • 测试
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$ hadoop jar Q1SumDeptSalary.jar Q1SumDeptSalary hdfs://hadoop:9000/class6/input/dept hdfs://hadoop:9000/class6/input/emp hdfs://hadoop:9000/class6/out1
$ hadoop fs -cat /class6/out1/part-r-00000
DEVELOP 44000
TEST 100000
UI 50000

求各个部门的人数和平均工资

  • 创建 Q2DeptNumberAveSalary.java,代码如下
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import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.filecache.DistributedCache;
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;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

public class Q2DeptNumberAveSalary extends Configured implements Tool {

public static class MapClass extends Mapper<LongWritable, Text, Text, Text> {

private Map<String, String> deptMap = new HashMap<String, String>();
private String[] kv;

@Override
protected void setup(Context context) throws IOException, InterruptedException {
BufferedReader in = null;
try {
Path[] paths = DistributedCache.getLocalCacheFiles(context.getConfiguration());
String deptIdName = null;
for (Path path : paths) {

if (path.toString().contains("dept")) {
in = new BufferedReader(new FileReader(path.toString()));
while (null != (deptIdName = in.readLine())) {

deptMap.put(deptIdName.split(",")[0], deptIdName.split(",")[1]);
}
}
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (in != null) {
in.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}

public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {

kv = value.toString().split(",");

if (deptMap.containsKey(kv[7])) {
if (null != kv[5] && !"".equals(kv[5].toString())) {
context.write(new Text(deptMap.get(kv[7].trim())), new Text(kv[5].trim()));
}
}
}
}

public static class Reduce extends Reducer<Text, Text, Text, Text> {

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

long sumSalary = 0;
int deptNumber = 0;

for (Text val : values) {
sumSalary += Long.parseLong(val.toString());
deptNumber++;
}

context.write(key, new Text("Dept Number:" + deptNumber + ", Ave Salary:" + sumSalary / deptNumber));
}
}

@Override
public int run(String[] args) throws Exception {

Job job = new Job(getConf(), "Q2DeptNumberAveSalary");
job.setJobName("Q2DeptNumberAveSalary");
job.setJarByClass(Q2DeptNumberAveSalary.class);
job.setMapperClass(MapClass.class);
job.setReducerClass(Reduce.class);

job.setInputFormatClass(TextInputFormat.class);

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

String[] otherArgs = new GenericOptionsParser(job.getConfiguration(), args).getRemainingArgs();
DistributedCache.addCacheFile(new Path(otherArgs[0]).toUri(), job.getConfiguration());
FileInputFormat.addInputPath(job, new Path(otherArgs[1]));
FileOutputFormat.setOutputPath(job, new Path(otherArgs[2]));

job.waitForCompletion(true);
return job.isSuccessful() ? 0 : 1;
}

public static void main(String[] args) throws Exception {
int res = ToolRunner.run(new Configuration(), new Q2DeptNumberAveSalary(), args);
System.exit(res);
}
}
  • 编译打包
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$ javac -classpath ../../hadoop-core-1.1.2.jar:../../lib/commons-cli-1.2.jar Q2DeptNumberAveSalary.java
$ jar cvf ./Q2DeptNumberAveSalary.jar ./Q2DeptNum*.class
$ mv *.jar /app/hadoop-1.1.2/
$ rm Q2DeptNum*.class
  • 测试
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$ hadoop jar Q2DeptNumberAveSalary.jar Q2DeptNumberAveSalary hdfs://hadoop:9000/class6/input/dept hdfs://hadoop:9000/class6/input/emp hdfs://hadoop:9000/class6/out2
$ hadoop fs -cat /class6/out2/part-r-00000
DEVELOP Dept Number:3, Ave Salary:14666
TEST Dept Number:6, Ave Salary:16666
UI Dept Number:3, Ave Salary:16666
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