怎么用java从hadoop中读数据

如果用eclipse 连接hadoop测试 一定要把core-site.xml  hdfs-site.xml 放到和包test同目录下 不然会报错程序会报File not found错误，并且加载相对应版本的的hadoop-core-xx.jar包

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1. package test;
   
2. import java.io.*;
   
3. import java.util.*;
   
4. import java.net.*;
   
5. import org.apache.hadoop.fs.*;
   
6. import org.apache.hadoop.conf.*;
   
7. import org.apache.hadoop.io.*;
   
8. import org.apache.hadoop.mapred.*;
   
9. import org.apache.hadoop.util.*;
   
10.  
    
11. public class Cat{
    
12.         public static void main (String [] args) throws Exception{
    
13.                 try{
    
14.                         Path pt=new Path("hdfs://10.14.2.201:9000/user/hadoop/words.txt");
    
15.                         //Path pt=new Path("hdfs://npvm11.np.wc1.yellowpages.com:9000/user/john/abc.txt");
    
16.                         FileSystem fs = FileSystem.get(new Configuration());
    
17.                         BufferedReader br=new BufferedReader(new InputStreamReader(fs.open(pt)));
    
18.                         String line;
    
19.                         line=br.readLine();
    
20.                         long sum = 0L;
    
21.                         while (line != null){
    
22.                                 sum ++;
    
23.                                 System.out.println(line+"sum: "+sum);
    
24.                                 line=br.readLine();
    
25.                         }
    
26.                 }catch(Exception e){
    
27.                     e.printStackTrace();
    
28.                 }
    
29.         }
    
30. }