Hadoop中自帶的hadoop-mapreduce-examples-2.7.6.jar含有一些事例,本文將用wordcount實現詞頻統計。具體步驟如下:
1. 啓動Hadoop
切換到Hadoop安裝目錄下的sbin目錄下執行./start-all.sh命令
或執行./start-dfs.sh和./start-yarn.sh兩條命令
2. 在集羣中創建目錄inputdata_w
hdfs dfs -mkdir /inputdata_w
3. 將Hadoop安裝目錄下的LICENSE.txt、README.txt、NOTICE.txt文件上傳到集羣
hdfs dfs -put ../LICENSE.txt /inputdata_w
hdfs dfs -put ../README.txt /inputdata_w
hdfs dfs -put ../NOTICE.txt /inputdata_w
4. 使用hadoop-mapreduce-examples-2.7.6.jar對上傳的數據進行詞頻統計
hadoop jar ../share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.6.jar wordcount /inputdata_w
/output/wordcountout01
5. 查看統計結果
hdfs dfs -cat /output/wordcountout01/part-r-00000