mapreduce程序本地运行单词统计案例，输入输出数据放在本地
集群模式运行：https://blog.csdn.net/weixin_43614067/article/details/108400938
本地提交给集群中运行：https://blog.csdn.net/weixin_43614067/article/details/108401227
统计单词文本，word.txt（位于C:\Users\Think\Desktop\input\word.txt）
Stray birds of summer
come to my window to sing and
fly away And yellow leaves of autumn
which have no songs flutter and fall there with a
sign O Troupe of little vagrants of the world l
eave your footprints in my
words The world puts off
its mask of vastness to its
lover It becomes small as one song
as one kiss of the eternal It is the tears of
the earth that keep her smiles in bloom The mighty desert
is burning for the love of a blade of grass
who shakes her head and laughs and flies
away If you shed tears when you miss the
sun you also miss the stars The sands in
your way beg for your song and your movement
dancing water Will you carry the burden of their
lameless Her wishful face haunts my dreams like the
rain at night Once we dreamt that we were strangers
We wake up to find that
we were dear to each other
Mapper端
package com.bjsxt.wc;
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 WCMapper extends Mapper<LongWritable, Text, Text, IntWritable>{
@Override
protected void map(LongWritable key, Text value, Context context)
throws IOException, InterruptedException {
//LongWritable为输入文本内容的每一行起始位置，value为每一行内容
String line = value.toString();
String[] words = line.split(" ");
for (String word : words) {
context.write(new Text(word), new IntWritable(1));
}
}
}
Reducer端
package com.bjsxt.wc;
import java.io.IOException;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.mapreduce.TableReducer;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;
public class WCReducer extends Reducer<Text, IntWritable, Text, IntWritable> {
@Override
protected void reduce(Text key, Iterable<IntWritable> values, Context context)
throws IOException, InterruptedException {
Integer count = 0;
for (IntWritable value : values) {
count += value.get();
}
context.write(key, new IntWritable(count));
}
}
Runner端
package com.bjsxt.wc;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.NullWritable;
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 WCRunner {
public static void main(String[] args) throws Exception {
//创建配置对象
Configuration conf = new Configuration();
//创建Job对象
Job job = Job.getInstance(conf, "wordCount");
//设置mapper类
job.setMapperClass(WCMapper.class);
//设置 Reduce类
job.setReducerClass(WCReducer.class);
//设置运行job类
job.setJarByClass(WCRunner.class);
//设置map输出的key,value类型
job.setMapOutputKeyClass(Text.class);
job.setMapOutputValueClass(IntWritable.class);
//设置reduce输出的key,value类型
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
//设置输入路径金额输出路径
/*FileInputFormat.setInputPaths(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));*/
FileInputFormat.setInputPaths(job, new Path("C:\Users\Think\Desktop\input\word.txt"));
FileOutputFormat.setOutputPath(job, new Path("C:\Users\Think\Desktop\output"))
long startTime = System.currentTimeMillis();
try {
//提交job
boolean b = job.waitForCompletion(true);
if (b) {
System.out.println("单词统计完成!");
}
} finally {
// 结束的毫秒数
long endTime = System.currentTimeMillis();
System.out.println("Job<" + job.getJobName() + ">是否执行成功:" + job.isSuccessful() + "; 开始时间:" + startTime + "; 结束时间:" + endTime + "; 用时:" + (endTime - startTime) + "ms");
}
}
}
注：使用
FileInputFormat.setInputPaths(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
运行需传入参数
结果如下图：
如果输入目录和输出目录一直，会报如下异常
在这里插入代码片`2020-09-03 16:37:03,938 INFO [main] Configuration.deprecation (Configuration.java:warnOnceIfDeprecated(1129)) - session.id is deprecated. Instead, use dfs.metrics.session-id
2020-09-03 16:37:03,942 INFO [main] jvm.JvmMetrics (JvmMetrics.java:init(76)) - Initializing JVM Metrics with processName=JobTracker, sessionId=
Exception in thread "main" org.apache.hadoop.mapred.FileAlreadyExistsException: Output directory file:/C:/Users/Think/Desktop/input already exists
at org.apache.hadoop.mapreduce.lib.output.FileOutputFormat.checkOutputSpecs(FileOutputFormat.java:146)
at org.apache.hadoop.mapreduce.JobSubmitter.checkSpecs(JobSubmitter.java:267)
at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:140)
at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1297)
at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1294)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:422)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1692)
at org.apache.hadoop.mapreduce.Job.submit(Job.java:1294)
at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:1315)
at com.bjsxt.wc.WCRunner.main(WCRunner.java:77)
Process finished with exit code 1`
解决办法：输入文本存在目录和输出目录不一致即可
mapreduce程序本地运行单词统计案例，输入输出数据放在hdfs中，增加修改如下配置
//本地运行，读取hdfs数据，并将数据提到hdfs
conf.set("fs.defaultFS", "hdfs://node001:8020");
FileInputFormat.setInputPaths(job, new Path("hdfs://node001:8020/wordcount/input"));
FileOutputFormat.setOutputPath(job, new Path("hdfs://node001:8020/wordcount/output"));
集群模式运行：https://blog.csdn.net/weixin_43614067/article/details/108400938
本地提交给集群中运行：https://blog.csdn.net/weixin_43614067/article/details/108401227