使用HDFS做一个记事本功能

 pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>ceshi</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>16</maven.compiler.source>
        <maven.compiler.target>16</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-hdfs</artifactId>
            <version>3.1.3</version>
        </dependency>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-client</artifactId>
            <version>3.1.3</version>
        </dependency>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-common</artifactId>
            <version>3.1.3</version>
        </dependency>
        <dependency>
            <groupId>org.apache.hbase</groupId>
            <artifactId>hbase-client</artifactId>
            <version>2.4.11</version>
        </dependency>
        <dependency>
            <groupId>org.apache.hbase</groupId>
            <artifactId>hbase-client</artifactId>
            <version>2.4.11</version>
        </dependency>
        <dependency>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
            <version>3.5.7</version>
        </dependency>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-mapreduce-client-core</artifactId>
            <version>3.1.3</version>
        </dependency>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-yarn-api</artifactId>
            <version>3.1.3</version>
        </dependency>

        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.11.0</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.2</version>
            <scope>test</scope>
        </dependency>

    </dependencies>

</project>

HDFS.java

package lianxi;

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.*;
import java.util.Scanner;

public class HDFS {

    public static FileSystem fs = null;
    Scanner sc = new Scanner(System.in);
    public static void main(String[] args) throws IOException {
        Scanner sc=new Scanner(System.in);
        Configuration configuration = new Configuration();
        System.setProperty("HADOOP_USER_NAME","hadoop");
        configuration.set("fs.defaultFS","hdfs://hadoop1:8020");
        fs = FileSystem.get(configuration);
        for (int i=0;;i++){
            System.out.println("请选择功能:1.创建文件 2.追加文件内容 3. 删除文件 4. 更改存储位置  5. 退出");
            int n=sc.nextInt();
            if (n==1){
                System.out.print("请输入将要创建文件的路径：");
                String path = sc.next();
                create(path);
            }else if (n==2){
                System.out.print("请输入想要追加文件的路径：");
                String path1 = sc.next();
                update(path1);
            }else if (n==3){
                System.out.println("请输入删除文件地址");
                String w=sc.next();
                delete(w);
            }else if (n==4){
                    System.out.println("请输入原地址");
                    String xinxi=sc.next();
                    String pp=readFromHdfs(xinxi);
                    System.out.print("请输入将要创建文件的路径：");
                    String pathw = sc.next();
                    create(pathw,pp);
                    delete(xinxi);
            }
            else break;
        }
        fs.close();
    }
    public static void create(String path) throws IOException {
        if(!fs.exists(new Path(path))){
            Scanner sc=new Scanner(System.in);
            FSDataOutputStream outputStream = fs.create(new Path(path));
            System.out.println("请输入需要文件中的内容");
            String s=sc.next();
            outputStream.writeUTF(s);
            System.out.println("创建文件夹成功");
            outputStream.flush();
            outputStream.close();
            FSDataInputStream open = fs.open(new Path(path));
            System.out.println(open.readUTF());
            open.close();
        }
    }
    public static void create(String path, String pp) throws IOException {
        if(!fs.exists(new Path(path))){
            Scanner sc=new Scanner(System.in);
            FSDataOutputStream outputStream = fs.create(new Path(path));
            System.out.println("请输入需要文件中的内容");
            outputStream.writeUTF(pp);
            System.out.println("创建文件夹成功");
            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("追加的内容");
        String s1 = sc.next();
        append.writeUTF(s1);
        append.flush();
        append.close();
        FSDataInputStream open = fs.open(new Path(path));
        System.out.println(open.readUTF());
    }
    public static void delete(String w) throws IOException {
        //带删除文件的目录路径
        Path src = new Path(w);
        //删除
        fs.delete(src,true);
        System.out.println("删除成功");
    }
    public static String readFromHdfs(String filePath) throws IOException{
        //读
        Path inFile = new Path(filePath);
        FSDataInputStream inputStream = fs.open(inFile);
        String pp=inputStream.readUTF();
        inputStream.close();
        return pp;
    }
}

test

package lianxi;

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.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;


public class test {
    public static FileSystem fs = null;
    public static void main(String[] args) throws Exception{
        Configuration conf = new Configuration();
        System.setProperty("HADOOP_USER_NAME", "hadoop");
        conf.set("fs.defaultFS", "hdfs://hadoop1:8020");
        fs = FileSystem.get(conf);
        if(!fs.exists(new Path("/lyh"))){
            fs.create(new Path("/lyh"));
        }

        create();

        copy();

        fs.close();
    }

    public static void create() throws Exception {
        if(!fs.exists(new Path("/ceshi/hdfstest1.txt"))){
            FSDataOutputStream output = fs.create(new Path("/ceshi/hdfstest1.txt"));
            output.write("20203959 李迎辉 HDFS课堂测试".getBytes());
            output.flush();
            System.out.println("创建获得hdfstest1成功");
            output.close();
        }
        else{
            System.out.println("创建获得hdfstest1失败");
        }
    }

    public static void copy() throws Exception {
        FSDataInputStream fin = fs.open(new Path("/test/hdfstest1.txt"));
        BufferedReader in = new BufferedReader(new InputStreamReader(fin, "UTF-8"));
        if(!fs.exists(new Path("/test/hdfstest2.txt"))){
            FSDataOutputStream fout  = fs.create(new Path("/test/hdfstest2.txt"));
            BufferedWriter out = new BufferedWriter(new OutputStreamWriter(fout, "UTF-8"));
            out.write(in.readLine());
            System.out.println("创建hdfstest2文件成功");
            out.flush();
            out.close();
        }else{
            System.out.println("创建hdfstest2文件失败");
        }

    }
}