hdfs课堂测试

补充某天的hdfs课堂测试，具体是哪天的，我也不记得了

看一下题目

直接上代码了

package com.rsh.hdfs.test2;

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

import java.io.IOException;
import java.util.Scanner;

public class HDFSTest {


    public static FileSystem fs = null;

    public static void main(String[] args) throws IOException {
        Configuration configuration = new Configuration();
        System.setProperty("HADOOP_USER_NAME","root");
        configuration.set("fs.defaultFS","hdfs://node1:8020");
        fs = FileSystem.get(configuration);
        Scanner sc = new Scanner(System.in);
        System.out.print("请输入将要创建文件的路径：");
        String path = sc.next();
        create(path);
        update(path);
        save(path);
        fs.close();
    }

    public static void create(String path) throws IOException {
        if(!fs.exists(new Path(path))){
            FSDataOutputStream outputStream = fs.create(new Path(path));
            outputStream.writeUTF("新建文件成功");
            outputStream.flush();
            outputStream.close();
            FSDataInputStream open = fs.open(new Path(path));
            System.out.println(open.readUTF());
            open.close();
        }
    }

    public static void update(String path) throws IOException {

        Scanner sc = new Scanner(System.in);
        FSDataOutputStream append = fs.append(new Path(path));
        System.out.print("请输入将要修改的内容：");
        String s = sc.next();
        append.writeUTF(s);
        append.flush();
        append.close();
        FSDataInputStream open = fs.open(new Path(path));
        System.out.println(open.readUTF());
    }

    public static void save(String path) throws IOException {

        Scanner sc = new Scanner(System.in);
        Path src = new Path(path);
        Path mid = new Path("D:\\test.txt");
        System.out.print("请输入文件将要另存的路径：");
        String savePath = sc.next();
        Path path1 = new Path(savePath);
        fs.copyToLocalFile(src,mid);
        fs.copyFromLocalFile(mid,path1);
        fs.close();
    }

}