HDFS API 简单示例

package com.rabbit.hadoop.hdfs;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import org.apache.hadoop.io.IOUtils;

import java.io.*;
import java.net.URI;

public class TestHDFS {

    public Configuration config = null;
    public FileSystem fs = null;

    public void conn() throws IOException, InterruptedException {
        config =  new Configuration(true);
//        FileSystem fs = FileSystem.get(config);
        fs = FileSystem.get(URI.create("hdfs://mycluster"),config,"bigdata");
    }

    public void mkdir() throws IOException, InterruptedException {
        this.conn();
        Path path = new Path("/user/bigdata/idea");
        fs.mkdirs(path);
        this.close();
    }

    public void upload() throws IOException, InterruptedException {
        this.conn();
        BufferedInputStream bis = new BufferedInputStream(new FileInputStream(new File("E:/a.txt")));
        Path path = new Path("/user/bigdata/idea/a.txt");
        FSDataOutputStream fsos = fs.create(path);
        IOUtils.copyBytes(bis,fsos,config,true);
        this.close();
    }

    public void download() throws IOException, InterruptedException {
        this.conn();
        Path path = new Path("/user/bigdata/idea/a.txt");
        FSDataInputStream fsis = fs.open(path);
        BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(new File("E:/a_hdfs.txt")));
        IOUtils.copyBytes(fsis, bos,config,true);
        this.close();
    }

    public void getBlocks() throws IOException, InterruptedException {
        this.conn();
        Path path = new Path("/user/bigdata/seq.txt");
        FileStatus fileStatus = fs.getFileStatus(path);
        BlockLocation[] blockLocations = fs.getFileBlockLocations(fileStatus, 0, fileStatus.getLen());

        for (BlockLocation blk : blockLocations) {
            System.out.println(blk);
        }

        FSDataInputStream fsis = fs.open(path);
        fsis.seek(1048576);
        System.out.println((char) fsis.readByte());
        System.out.println((char) fsis.readByte());
        System.out.println((char) fsis.readByte());
        System.out.println((char) fsis.readByte());
        System.out.println((char) fsis.readByte());
        System.out.println((char) fsis.readByte());
        System.out.println((char) fsis.readByte());
        System.out.println((char) fsis.readByte());
        System.out.println((char) fsis.readByte());
        System.out.println((char) fsis.readByte());
        System.out.println((char) fsis.readByte());
        System.out.println((char) fsis.readByte());
        System.out.println((char) fsis.readByte());
        System.out.println((char) fsis.readByte());

        this.close();
    }

    public void close() throws IOException {
        fs.close();
    }

    public static void main(String[] args) throws IOException, InterruptedException {
        TestHDFS test = new TestHDFS();
//        test.mkdir();
//        test.upload();
//        test.download();
        test.getBlocks();

    }

}