hadoop hdfs 파일저장 및 읽기 예제

1. pom.xml

   <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemalocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
       <modelVersion>4.0.0</modelVersion>
       <groupId>com.dbility.hadoop</groupId>
       <artifactId>example01</artifactId>
       <version>0.0.1</version>
       <build>
           <finalName>${project.artifactId}</finalName>
       </build>
       <properties>
           <hadoop.version>1.2.1</hadoop.version>
           <slf4j.version>1.4.3</slf4j.version>
       </properties>
       <dependencies>
           <dependency>
               <groupId>org.apache.hadoop</groupId>
               <artifactId>hadoop-core</artifactId>
               <version>${hadoop.version}</version>
           </dependency>
           <dependency>
               <groupId>org.slf4j</groupId>
               <artifactId>slf4j-api</artifactId>
               <version>${slf4j.version}</version>
           </dependency>  
       </dependencies>
   </project>

2. SimpleFileWriteRead.java

   package com.dbility.hadoop;
   
   import org.apache.hadoop.conf.Configuration;
   import org.apache.hadoop.fs.FSDataInputStream;
   import org.apache.hadoop.fs.FSDataOutputStream;
   import org.apache.hadoop.fs.FileSystem;
   import org.apache.hadoop.fs.Path;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   public class SingleFileWriteRead {
   
   	private static final Logger LOG = LoggerFactory.getLogger(SingleFileWriteRead.class);
   
   	public static void main(String[] args) {
   
   		if (args.length != 2) {
   			LOG.info("Usage : <filename> <contents>");
   			Runtime.getRuntime().exit(1);
   		}
   
   		try {
   			Configuration conf = new Configuration();
   			FileSystem hdfs = FileSystem.get(conf);
   
   			Path path = new Path(args[0]);
   
   			if ( hdfs.exists(path) ){
   				hdfs.delete(path, true);
   			}
   
   			FSDataOutputStream outputStream = hdfs.create(path);
   			outputStream.writeUTF(args[1]);
   			outputStream.close();
   
   			FSDataInputStream inputStream = hdfs.open(path);
   			String inputString = inputStream.readUTF();
   			inputStream.close();
   
   			LOG.info("contents : {}",inputString);
   
   		} catch (Exception e) {
   			LOG.info("Error : {}", e.getMessage());
   		}
   	}
   }

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