hadoop非mapreduce过程对hdfs文件的读写

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package cn.ytu.hdfsrwfile;import java.util.ArrayList;import java.util.List;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.fs.FSDataInputStream;import org.apache.hadoop.fs.FileSystem;import org.apache.hadoop.fs.Path;/** * 非mapreduce过程在HDFS上读文件 * @author LiuYinxing * */public class ReadHDFSfile {/** * 非mapreduce过程在HDFS上读取文件 * @param path  文件路径 * @return 内容 * @throws Exception */@SuppressWarnings("deprecation")public List<String> getData(String path) throws Exception{Configuration conf = new Configuration();FileSystem hdfs = FileSystem.get(conf);Path inPath  = new Path(path);FSDataInputStream dis = hdfs.open(inPath);    String s = null;    s = dis.readLine();    String[] strings = s.split(",");    List<String> attributesvalue = new ArrayList<>();    for (int i = 0; i < strings.length; i++) {attributesvalue.add(strings[i]);}    return attributesvalue;}}

package cn.ytu.hdfsrwfile;import java.io.FileNotFoundException;import java.io.IOException;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.fs.FSDataOutputStream;import org.apache.hadoop.fs.FileSystem;import org.apache.hadoop.fs.Path;/** * 非mapreduce过程在HDFS上写文件 * @author LiuYinxing * */public class WriteHDFSfile {/** * 非mapreduce过程在HDFS上写文件 * @param path * @throws FileNotFoundException * @throws IOException */  public void writehdfsdata(String path) throws FileNotFoundException, IOException  {    String string = "hello world i love you";Configuration conf = new Configuration();FileSystem hdfs = FileSystem.get(conf);Path inPath  = new Path(path);FSDataOutputStream dos = hdfs.create(inPath);dos.writeBytes(string);dos.close();}}

package cn.ytu.hdfsrwfile;public class HRWmain {public static void main(String[] args) throws Exception {// TODO Auto-generated method stubString path = "hdfs://localhost:9000/user/hadoop/output/helloworld.txt";WriteHDFSfile writeHDFSfile = new WriteHDFSfile();writeHDFSfile.writehdfsdata(path);ReadHDFSfile readHDFSfile = new ReadHDFSfile();for (String string : readHDFSfile.getData(path)) {System.out.print(string+" ");}System.out.println();}}

运行结果如下：

注意如果在eclipse上运行出现如下异常：

请参考上篇博客：

hadoop程序抛出异常：java.lang.IllegalArgumentException: Wrong FS: hdfs:/ expected file:///

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