编程操作hdfs文件

可实现对文件的访问，如创建、修改、删除等。

工具是IDEA

代码如下：

 import java.io.*;
 import java.util.Scanner;

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


 public class hdfs {
        //判断路径是否存在
        public static boolean test(Configuration conf,String path) throws  IOException
        {
            FileSystem fs=FileSystem.get(conf);
            return fs.exists(new Path(path));
        }
        //创建目录
        public static boolean mkdir (Configuration conf ,String remoteDir)throws IOException
        {
            FileSystem fs=FileSystem.get(conf);
            Path dirPath=new Path(remoteDir);
            boolean result=fs.mkdirs(dirPath);
            fs.close();
            return result;
        }
        //创建文件
       public static void touchz(Configuration conf,String remoteFilePath )throws IOException
        {
            FileSystem fs=FileSystem.get(conf);
            Path remotePath=new Path(remoteFilePath);
            FSDataOutputStream outputStream =fs.create(remotePath);
            outputStream.close();
            fs.close();
      }
        //删除文件
        public static boolean rm(Configuration conf,String remoteFilePath)throws IOException
        {
            FileSystem fs=FileSystem.get(conf);
            Path remotePath=new Path(remoteFilePath);
            boolean result=fs.delete(remotePath,false);
            fs.close();
            return result;
         }
        //读文件
        public static void cat(Configuration conf,String FilePath)throws IOException
        {
            FileSystem fs=FileSystem.get(conf);
            Path file=new Path(FilePath);
            FSDataInputStream getIt=fs.open(file);
            BufferedReader d=new BufferedReader(new InputStreamReader(getIt));
            String content=d.readLine();
            System.out.println(content);
            d.close();
            fs.close();
        }
        //追加文件内容
        public static void appendContentToFile(Configuration conf,String content,String remoteFilePath)throws IOException
        {
            System.out.println("追加的位置：1.开头  2.结尾");
            Scanner tt=new Scanner(System.in);
            int cc=tt.nextInt(); //输入整型
            if(cc==1){
           //追加到开头
           //先获取文件内容，再字符串拼接。
           FileSystem fs=FileSystem.get(conf);
           Path file=new Path(remoteFilePath);
           FSDataInputStream getIt=fs.open(file);
           BufferedReader d=new BufferedReader(new InputStreamReader(getIt));
           String cont=d.readLine();
           fs.close();
           hdfs.rm(conf,remoteFilePath);//删除
           hdfs.touchz(conf, remoteFilePath);//新建
           //字符串拼接
           cont=content+cont;
           FileSystem fs1=FileSystem.get(conf);
           Path file1=new Path(remoteFilePath);
           FSDataOutputStream out=fs1.append(file1);
           out.write(cont.getBytes());
           out.close();
           fs1.close();
            }else if(cc==2){
           //追加到结尾
            FileSystem fs=FileSystem.get(conf);
              Path remotePath=new Path(remoteFilePath);
              FSDataOutputStream out=fs.append(remotePath);
              out.write(content.getBytes());
               out.close();
            fs.close();
            }else{
           System.out.println("请重新输入!");
             }
           }
            //将文件1写入文件2
            public static void appendContentToFile2(Configuration conf,String  remoteFilePath,String remoteFilePath2)throws IOException
            {
                FileSystem fs=FileSystem.get(conf);
                Path file=new Path(remoteFilePath);
                FSDataInputStream  getIt=fs.open(file);
                BufferedReader d=new BufferedReader(new InputStreamReader(getIt));
                String content1=d.readLine();

                Path remotePath=new Path(remoteFilePath2);
                FSDataOutputStream out=fs.append(remotePath);
                out.write(content1.getBytes());
                d.close();
                out.close();
                fs.close();
            }

            public static void main(String[] args)
        {
            Configuration conf=new Configuration();
            conf.set("dfs.client.block.write.replace-datanode-on-failure.policy","NEVER");
            conf.set("dfs.client.block.write.replace-datanode-on-failure.enable","true");
            conf.set("fs.default.name", "hdfs://192.168.58.128:9000");
            conf.set("fs.hdfs.impl","org.apache.hadoop.hdfs.DistributedFileSystem");
            String remoteDir ="/user/hadoop/LZY";//HDFS目录
            String remoteFilePath="/user/hadoop/LZY/hdfstest1.txt";
            String content="信1805-820183542刘子煜HDFS课堂测试";
          //创建目录
            int i=1;
            while(i!=0){
            Scanner input=new Scanner(System.in);
            System.out.println("请输入:");
            System.out.println("1.新建文本目录    2.新建文本文件    3.编辑");
            System.out.println("4.打开文本文件    5.删除文件     6.退出");
            int contents=input.nextInt(); //输入整型
            if(contents==1){
            System.out.println("请输入目录路径");
            Scanner input1=new Scanner(System.in);
            remoteDir =input1.next();
            try {
               if(!hdfs.test(conf, remoteDir))
               {
                   hdfs.mkdir(conf, remoteDir);
                   System.out.println("创建目录"+remoteDir);
               }
               else
               {
                   System.out.println(remoteDir+"目录已存在");
               }
            } catch (IOException e) {
            e.printStackTrace();
                }
            }else if(contents==2){
                    System.out.println("请输入文件名字和具体路径");
                    Scanner input1=new Scanner(System.in);
                    remoteFilePath =input1.next();
                try {
               //创建文件
               if (!hdfs.test(conf, remoteFilePath)) {
                   hdfs.touchz(conf, remoteFilePath);
                   System.out.println("创建文件" + remoteFilePath+"成功");
               } else {
                   System.out.println(remoteFilePath + "已存在，创建失败！");
               }
                    }catch (IOException e) {
                   e.printStackTrace();
               }

       }else if(contents==3){
           try {
               //向文件内输入
               System.out.println("请输入文本内容：");
               Scanner input1=new Scanner(System.in);
               content =input1.next();
               System.out.println("请输入文件目录：");
               Scanner input2=new Scanner(System.in);
               remoteFilePath =input2.next();
               hdfs.appendContentToFile(conf, content, remoteFilePath);
               hdfs.cat(conf, remoteFilePath);
           }catch (IOException e) {
               e.printStackTrace();
           }
       }else if(contents==4){
           try {
                   System.out.println("请输入要打开的目录及文件名:");
                   Scanner input2=new Scanner(System.in);
                   remoteFilePath =input2.next();
                   hdfs.cat(conf,remoteFilePath);
               }catch (IOException e) {
                   e.printStackTrace();
         }
       }else if(contents==5){
           try {
               System.out.println("请输入要删除的目录及文件名:");
               Scanner input2=new Scanner(System.in);
               remoteFilePath =input2.next();
               hdfs.rm(conf,remoteFilePath);
               System.out.println(remoteFilePath+"已删除成功！");
           }catch (IOException e) {
               e.printStackTrace();
           }

       }else if(contents==6){
           i=0;
       }
         }
        }
}