實做四: Hadoop 程式編譯

前言：啟動Hadoop環境

• 重新啟動昨天的環境
  • 在 node1 上操作

    $ cd /opt/hadoop
    $ bin/hadoop start-dfs.sh
    $ ssh node02 "bin/hadoop start-mapred.sh"
    

  • 請檢查 hadoop 是否正確運作.

練習 1 : Word Count 初級版

• 上傳內容到hdfs內

$ cd /opt/hadoop
$ bin/hadoop dfs -mkdir input
$ echo "I like NCHC Cloud Course." > input1
$ echo "I like nchc Cloud Course, and we enjoy this course." > input2
$ bin/hadoop dfs -put input1 input
$ bin/hadoop dfs -put input2 input
$ bin/hadoop dfs -ls input

• 點此連結 WordCount.java​ 並將他存到 /opt/hadoop

wget http://trac.nchc.org.tw/cloud/attachment/wiki/jazz/Hadoop_Lab6/WordCount.java?format=raw

• 運作程式

$ mkdir MyJava
$ javac -classpath hadoop-*-core.jar -d MyJava WordCount.java
$ jar -cvf wordcount.jar -C MyJava .
$ bin/hadoop jar wordcount.jar WordCount input/ output/
$ bin/hadoop dfs -cat output/part-00000

---

練習 2 : Word Count 進階版

$ echo "\." >pattern.txt && echo "\," >>pattern.txt
$ bin/hadoop dfs -put pattern.txt ./
$ mkdir MyJava2

• 點此連結 WordCount2.java​ 並將他存到 /opt/hadoop

$ javac -classpath hadoop-*-core.jar -d MyJava2 WordCount2.java
$ jar -cvf wordcount2.jar -C MyJava2 .
$ bin/hadoop jar wordcount2.jar WordCount2 input output2 -skip pattern.txt
$ bin/hadoop dfs -cat output2/part-00000
$ bin/hadoop jar wordcount2.jar WordCount2 -Dwordcount.case.sensitive=false input output3 -skip pattern.txt
$ bin/hadoop dfs -cat output3/part-00000