1. 上传数据到hdfs目录

[hadoop@uhadoop-******-master1 pig]$ hadoop fs -put /etc/passwd /user/hadoop/passwd

1. 启动pig

[hadoop@uhadoop-******-master1 pig]$ pig

1. 加载数据

grunt> A = load 'passwd' using PigStorage(':');
grunt> dump A;

显示结果：

(root,x,0,0,root,/root,/bin/bash) 
……

• 准备数据

student 文件内容

any 9 5
bob 8 4

上传student文件

hdfs dfs -put student /user/root/student

• 示例代码

java package myudfs; import java.io.IOException; import org.apache.pig.EvalFunc; import org.apache.pig.data.Tuple; public class UPPER extends EvalFunc { public String exec(Tuple input) throws IOException { if (input == null || input.size() == 0 || input.get(0) == null) return null; try{ String str = (String)input.get(0); return str.toUpperCase(); }catch(Exception e){ throw new IOException("Caught exception processing input row ", e); } } }

• 编译

cd myudfs
javac -cp $ PIG_HOME/pig-0.12.0-cdh5.4.4.jar UPPER.java
cd ..
jar -cf myudfs.jar myudfs

测试脚本upper.pig

pig REGISTER myudfs.jar; A = LOAD 'student' AS (name: chararray, age: int, gpa: float); B = FOREACH A GENERATE myudfs.UPPER(name); DUMP B;

• 执行

pig upper.pig

• 输出结果

  (ANY 9 5) (BOB 8 4)