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;
}
}
}
}