在HDFS中读写文件（JAVA）

查看文件内容

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URI;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

public class HCat{
    
    public void cat(String fpname) throws Exception{
    
        Path path = new Path(fpname);
        FileSystem fs = FileSystem.get(new URI("hdfs://localhost"), new Configuration());
        BufferedReader br = new BufferedReader(new InputStreamReader(fs.open(path)));
        String line = br.readLine();
        while(line != null){
            System.out.println(line);
            line = br.readLine();
        }
        br.close();
    }

    public static void main(String[] args){
        HCat hcat = new HCat();
        try{
            hcat.cat("/temp/usr/install.log");
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

往HDFS中上传文件

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.net.URI;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

public class HPut {

    // rpath --source filename
    // dpath --target path
    // fname --target name
    public void put(String rpath, String dpath, String fname) throws Exception {
        Path path = new Path(dpath);
        FileSystem fs = FileSystem.get(new URI("hdfs://localhost"), new Configuration());
        // if(fs.exists(path)){
        // fs.delete(path, true);
        // }
        if (!fs.exists(path)) {
            fs.mkdirs(path);
            Path filePath = new Path(dpath + fname);
            StringBuffer sb = new StringBuffer();
            File f = new File(rpath);
            BufferedReader br = new BufferedReader(new FileReader(f));
            String line = br.readLine();
            while (line != null) {
                System.out.println(line);
                sb.append(line);
                line = br.readLine();
            }
            FSDataOutputStream out = fs.create(filePath);
            byte[] bytes = br.toString().getBytes();
            out.write(bytes);
            br.close();
            out.close();
        }

    }

    public static void main(String[] args) {
        HPut hput = new HPut();
        try {
            hput.put("/home/root/HCat.java", "/temp/usr/test/", "HCat.java");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}