作业13答案

package cn.edu.zucc.hdfs; 

import java.io.BufferedReader;
import java.io.IOException; 
import java.io.InputStream; 
import java.io.InputStreamReader; 
import org.apache.hadoop.conf.Configuration; 
import org.apache.hadoop.fs.*; 

public class MyFSDataInputStream extends FSDataInputStream { 

    public MyFSDataInputStream(InputStream in) { 
        super(in); 
    } 

    public static String readline(Configuration conf, String remoteFilePath) { 
        try (FileSystem fs = FileSystem.get(conf)) { 
            Path remotePath = new Path(remoteFilePath); 
            FSDataInputStream in = fs.open(remotePath); 
            BufferedReader d = new BufferedReader(new InputStreamReader(in)); String line = null; 
            if ((line = d.readLine()) != null) { 
                d.close(); 
                in.close(); 
                return line; 
            } 
            return null; 
        } catch (IOException e) { 
            // TODO Auto-generated catch block e.printStackTrace(); 
            return null; 
        } 
    } 

    public static void main(String[] args) { 
        Configuration conf = new Configuration(); 
        conf.set("fs.default.name", "hdfs://localhost:9000"); 
        String remoteFilePath = "/user/text.txt"; // HDFS路径 

        System.out.println("读取文件: " + remoteFilePath); 
        System.out.println(MyFSDataInputStream.readline(conf, remoteFilePath)); 
        System.out.println("\n读取完成"); 
    } 
}