Hadoop中自带的examples之wordcount应用案例，hadoopwordcount
大家都知道hadoop中自带了很多例子，那么怎么用呢，今天主要测试下hadoop中的wordcount程序jar包：
1、首先启动hadoop
2、准备数据：vim words， 写入
hello tom
hello jerry
hello kitty
hello tom
hello bbb
3、将数据上传到HDFS
hadoop fs -put words /user/guest/words.txt
4、运行examples中自带的wordcount程序jar包
guest@master:/usr/hadoop/share/hadoop/mapreduce$ hadoop jar hadoop-mapreduce-examples-2.4.0.jar
An example program must be given as the first argument.
Valid program names are:
aggregatewordcount: An Aggregate based map/reduce program that counts the words in the input files.
aggregatewordhist: An Aggregate based map/reduce program that computes the histogram of the words in the input files.
bbp: A map/reduce program that uses Bailey-Borwein-Plouffe to compute exact digits of Pi.
dbcount: An example job that count the pageview counts from a database.
distbbp: A map/reduce program that uses a BBP-type formula to compute exact bits of Pi.
grep: A map/reduce program that counts the matches of a regex in the input.
join: A job that effects a join over sorted, equally partitioned datasets
multifilewc: A job that counts words from several files.
pentomino: A map/reduce tile laying program to find solutions to pentomino problems.
pi: A map/reduce program that estimates Pi using a quasi-Monte Carlo method.
randomtextwriter: A map/reduce program that writes 10GB of random textual data per node.
randomwriter: A map/reduce program that writes 10GB of random data per node.
secondarysort: An example defining a secondary sort to the reduce.
sort: A map/reduce program that sorts the data written by the random writer.
sudoku: A sudoku solver.
teragen: Generate data for the terasort
terasort: Run the terasort
teravalidate: Checking results of terasort
wordcount: A map/reduce program that counts the words in the input files.
wordmean: A map/reduce program that counts the average length of the words in the input files.
wordmedian: A map/reduce program that counts the median length of the words in the input files.
wordstandarddeviation: A map/reduce program that counts the standard deviation of the length of the words in the input files.
从这里可以看到wordcount程序；然后执行：
hadoop jar hadoop-mapreduce-examples-2.4.0.jar wordcount /user/guest/words.txt /user/guest/wordcount
查看结果：hello 5 Jerry 1 kitty 1 tom 2 bbb 1
版权声明：本文为博主原创文章，未经博主允许不得转载。