使用Java Api操作HDFS过程详解

<dependencies>    <dependency>      <groupId>junit</groupId>      <artifactId>junit</artifactId>      <version>4.10</version>    </dependency>        <!-- hadoop Client -->    <dependency>      <groupId>org.apache.hadoop</groupId>      <artifactId>hadoop-client</artifactId>      <version>${hadoop.version}</version>    </dependency>    </dependencies>

package com.zuoyan.hadoop.hdfs;import java.io.File;import java.io.FileInputStream;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.apache.hadoop.io.IOUtils;/** * use java api operate hdfs *  * @author beifeng *  */public class HdfsApp {  // get FileSystem  public static FileSystem getFileSystem() throws Exception {    Configuration conf = new Configuration();    FileSystem fileSystem = FileSystem.get(conf);    return fileSystem;  }  public static void read(String fileName) throws Exception {    FileSystem fileSystem = getFileSystem();    // read Path    Path readPath = new Path(fileName);    FSDataInputStream inStream = fileSystem.open(readPath);    try {      IOUtils.copyBytes(inStream, System.out, 4096, false);    } catch (Exception e) {      // TODO: handle exception      e.printStackTrace();    } finally {      // if Exception close Stream      IOUtils.closeStream(inStream);    }  }  public static void main(String[] args) throws Exception{            //String fileName = "/user/beifeng/mapreduce/wordcount/input/wc.input";      //read(fileName);          FileSystem fileSystem = getFileSystem();      //write path      String putFileName = "/user/beifeng/put-wc.input";            Path writePath = new Path(putFileName);            FSDataOutputStream outputStream = fileSystem.create(writePath);            FileInputStream inputStream = new FileInputStream(          new File("/opt/modules/hadoop-2.5.0/wc.input"));            try {        IOUtils.copyBytes(inputStream, outputStream, 4096,false);      } catch (Exception e) {        // TODO: handle exception        inputStream.close();        outputStream.close();      }      }}